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Ear: External, Middle, and Temporal Bone
Introduction
Lesions of the ear reflect the composition and environmental exposures of the ear’s constituent parts: the skin, subcutaneous tissues, and cartilage of the external ear; the mucosa, ossicles and bone, nerves, muscles, and blood vessels of the middle ear and mastoid; and the specialized epithelium and nerves of the inner ear, which, encased within the temporal bone, transmute sound and position sensation to electrical impulses and produce and regulate the flow of endolymph.
Embryologically, the ear is formed by the intersection of three developmental embryonic layers “not causally connected in development but linked together only through the medium of their definitive functioning” (Yntema cited by Van De Water and Rubin ). The external ear, including the pinna or auricle, external auditory meatus, and canal to the squamous epithelial layer of the tympanum (eardrum), is formed by the ectoderm and mesoderm of the first branchial groove and adjacent first (mandibular) and second (hyoid) branchial arches.
The middle ear epithelium, lining the auditory (eustachian) tube, middle ear, and mastoid cavities, is an endodermal derivative of the first pharyngeal pouch, with mesodermal contributions lining the mastoid and epitympanic and hypotympanic cavities. The tympanic membrane is derived from both external and middle ear; the external squamous surface is contiguous with that of the external auditory canal, and an endodermally derived simple cuboidal, columnar, or flat epithelium lines the middle ear. A portion of the tympanum, the pars flaccida, lacks an intermediate mesenchyme. The middle ear ossicles and supporting tissues are first and second branchial arch mesenchyme derivatives.
The inner ear develops, by mesodermal and neural induction, from the ectodermal otic placode rather than from the branchial apparatus. An appreciation of the embryologic origins of the ear is useful in interpreting the origins of tumors, the potential of cells for metaplastic change, and discussions of choristoma and the origin of cholesteatoma.
Ross and Sasaki review the surgical anatomy of the ear in their discussion of radical temporal bone surgery for malignant tumors. Michaels’s presentation of the histology of the ear is comprehensive and well illustrated, as is the ear, nose, and throat pathology text by Michaels and Hellquist.
The majority of ear lesions submitted for pathologic examination (biopsy) are: (1) from the skin of the external ear (pinna, meatus, or canal); (2) inflammatory (8:1 ratio of inflammatory to neoplastic lesions ); and (3) due to traumatic or actinic insults.
Analysis of tumors of the ear from major referral centers and community and university hospitals shows similar frequencies of tumor types and location ( Table 12.1 ). In the Barnes Hospital, St. Louis, MO, series, the most common tumors, in order of frequency, were squamous cell and basal cell carcinomas, predominantly of the external ear (45%); paragangliomas of the middle ear (14%); middle ear adenomas (10%); osteomas of the external canal (7%); carcinomas not otherwise specified (6%); nerve sheath tumors (3%); and nevi or melanomas of the external ear (3%). Remaining were miscellaneous benign and malignant mesenchymal tumors, including rhabdomyosarcoma (RMS; 1%) in children.
TABLE 12.1
Frequency (%) of Ear Neoplasms at Four Institutions
| Neoplasm | BH a | AFIP † | YNH † | BPT † |
|---|---|---|---|---|
| Squamous | 48 | 53 | 66 | 61 |
| Benign cysts, papilloma, etc. | 3 | 4 | 6 | 17 |
| Squamous cell carcinoma | 35 | 27 | 27 | 16 |
| Basal cell carcinoma | 10 | 22 | 26 | 11 |
| Neuroepithelial/neural | 21 | 26 | 25 | 16 |
| Nevi | 2 | 6 | 12 | 8 |
| Melanoma | 1 | 2 | 9 | 2 |
| Nerve sheath | 3 | 12 | 4 | |
| Schwannoma | 12 | 2 | ||
| Neurofibroma | <1 | 1 | ||
| Granular cell | 1 | <1 | ||
| Paraganglioma | 14 | 4 | 3 | 0 |
| Merkel cell carcinoma | <1 | <1 | ||
| Meningioma | 1 | <1 | ||
| Heterotopic brain | <1 | |||
| Neuroblastoma | <1 | |||
| Glandular | 10 | 11 | 1 | 2 |
| Adenoma | 6 | 5 | <1 | <1 |
| Auricle | <1 | |||
| External canal | 3 | 2 | <1 | |
| Middle ear | 3 | 3 | <1 | <1 |
| Adenocarcinoma | 4 | 3 | 0 | 0 |
| Carcinoma not otherwise specified | 6 | |||
| Benign not otherwise specified | 2 | |||
| Metastases | <1 | 2 | 2 | <1 |
| Malignant not otherwise specified | 1 | <1 | ||
| Mesenchymal lesions | 12 | 11 | 5 | 24 |
| Fibrohistiocytic | ||||
| Benign | 2 | 1 | 1 | |
| Malignant | <1 | |||
| Keloid | 15 | |||
| Leiomyoma | <1 | |||
| Leiomyosarcoma | <1 | |||
| Rhabdomyosarcoma | <1 | 2 | <1 | <1 |
| Sarcoma not otherwise specified | 1 | |||
| Vascular | 2 | <1 | 1 | 2 |
| Kaposi sarcoma | <1 | |||
| Lymphangioma | <1 | |||
| Hemangioma | 2 | 1 | 2 | |
| Bone/cartilage | 7 | 4 | <1 | 1 |
| Benign | 7 | 4 | <1 | 1 |
| Malignant | <1 | |||
| Langerhans cell histiocytosis | <1 | <1 | <1 | |
| Lymphoproliferative | 1 | <1 | ||
| Congenital | <1 | |||
| Dermoid | <1 | |||
| Hamartoma | <1 | |||
| Choristoma | <1 | |||
| Tragus | <1 | |||
| Total | 219 | 1781 | 235 | 293 |
a Barnes Hospital (BH) data derived from Table 13.1 in Davis G.L., 1988. Tumors and inflammatory conditions of the ear. In Gnepp D.R. (Ed). Pathology of the Head and Neck. Churchill Livingstone, New York, p 548.
† Armed Forces Institute of Pathology (AFIP) data derived from Table 25 in Hyams V.J., Batsakis J.G., Michaels L., 1988. Tumors of the upper respiratory tract and ear. In Atlas of Tumor Pathology, 2nd Series, Fascicle 25. Armed Forces Institute of Pathology, Washington, DC, p. 260–261; Dagger; Yale–New Haven (YNH) and Bridgeport Hospital–Bridgeport Pathology Consultants (BPT).
Lesions of the internal auditory canal are underrepresented in these series. The relative numbers of lesions of the external ear and nevi or melanoma and acoustic neuroma vary depending on the nature of the referring services, that is, otology, dermatology, or neurosurgery.
Neoplasms of the ear are rare relative to inflammatory lesions. However, because they occur in the same age groups and have similar clinical presentations, biopsy sample differentiation between inflammation and neoplasia (benign or malignant) is necessary and often difficult.
Lesions of the external ear are predominantly lumps and bumps of skin and cartilage origin in elderly individuals. Tumors of the external canal are often not visible and are manifested early by fullness and later by a mass, fluid drainage, or bloody discharge. Hearing loss and pain are symptoms of increasing size and invasion, and are clinical manifestations of malignancy. Ulceration and superimposed inflammation can lead to an erroneous diagnosis of inflammation, but, except for otitis in diabetic patients, necrotic inflammatory masses are usually necrotic tumors. Evaluation of the site, size, and spread of neoplastic lesions with sophisticated imaging techniques is mandatory.
Middle ear lesions present with hearing loss, and, with an otoscope, a mass can be seen behind the normal or bulging eardrum. Chronic otitis media is a sequel of acute otitis media in children, but in adults, chronic otitis media is a sign of a systemic disease or neoplasm. Hearing loss occurs early in the course of middle ear disease owing to encroachment on the conductive chain of ossicles. An enlarging lesion can cause the drum to bulge into the external canal or destroy the drum. Both neoplasms and infection spread from the middle ear posteriorly into the mastoid, medially into the jugular fossa, and superiorly through the tegmen into the cranial cavity and laterally through the drum.
Lesions of the inner ear, located within the temporal bone, had been relatively inaccessible to biopsy, but with current imaging techniques, fine-needle aspiration biopsy, endoscopes, and recently developed base of the skull neuro-otologic techniques, no part of the ear is unreachable by skilled operators.
Inner ear tumors are predominantly nerve sheath tumors, meningiomas, and rare lipomatous tumors of the eighth cranial nerve involving the internal auditory meatus. Aggressive papillary middle ear tumors and endolymphatic sac tumors (associated with von Hippel-Lindau disease), remain rare and controversial lesions.
Secondary tumors in the ear/temporal bone are invariably late manifestations of previously diagnosed tumors, either as metastases or direct local invasion.
External Ear
Lumps and Bumps
With few exceptions, lesions of the external ear are similar to lesions of the skin and soft tissues in other parts of the body, and particularly reflect exposure of the skin and underlying cartilage to environmental actinic injury ( Table 12.2 ).
TABLE 12.2
Differential Diagnosis of Nodules of the External Ear
Adapted from Lawrence, C.M., 1996. Chondrodermatitis nodularis. In Arndt, K.A., Le Boit, P.E., Robinson, J.K., et al. (Eds). Cutaneous Medicine and Surgery. WB Saunders, Philadelphia, p 509.
| Condition | Site |
|---|---|
| Painful Nodules | |
| Chondrodermatitis nodularis | |
| Basal cell carcinoma (if secondarily ulcerated and infected) | |
| Squamous cell carcinoma | |
| Keratoacanthoma | |
| Actinic keratosis | |
| Painless nodules | |
| Basal cell carcinoma | Any site; pearly edge with telangiectasia |
| Squamous cell carcinoma | Top surface of helix |
| Keratoacanthoma | Top surface of helix |
| Actinic keratosis | Top surface of helix, not discrete |
| Elastotic nodule | Bilateral pearly papules on anterior antihelix |
| Gouty tophi | Creamy papules on helix and antihelix, aspirate urate crystals |
| Cartilaginous pseudocyst | Fluctuant swelling in upper half of auricle, aspirate oily fluid |
| Pseudopyogenic granuloma | Multiple itchy nodules in concha |
| Painful Swollen Ear | |
| Relapsing polychondritis | Entire earlobe is inflamed; other areas of cartilage affected |
| Subperichondral hematoma | Recent trauma with hemorrhage |
| Acute perichondritis | Infected ear, systemic symptoms |
| Earlobe Swelling | |
| Local disease | Keloid, epidermal cyst, granuloma, viral wart, acne cyst |
| Systemic disease | Leukemia/lymphoma, sarcoid granulomas |
Congenital Developmental Anomalies
Congenital anomalies of the external ear include the deformed pinna and persistent tracts, pits, cysts, duplications, and anomalous (hamartomatous) glandular tissues in and around the external and middle ear, exemplifying the complexities of embryologic branchial arch derivation.
Accessory Tragus
As reported in the previous edition of this chapter by Dr. Gustave Davis, the most common congenital lesion in the Bridgeport Pathology files (see Table 12.1 ) was the accessory tragus located anterior to the tragus of the external ear. When large and pedunculated, it has been referred to as a “wattle.” Removed from infants for cosmetic reasons, the accessory tragus consists of a central core of cartilage that is surrounded by normal skin ( Fig. 12.1 ). Accessory tragus most often occurs sporadically but can be associated with the congenital Goldenhar syndrome (oculoauriculovertebral dysplasia).
Preauricular Cysts and Sinuses
Clinical Features
Preauricular cysts and fistulous tracts above the hyoid bone and associated with the parotid gland and external ear are derived from the first branchial arch. Cysts and tracts may persist into adulthood and become secondarily infected and drain, or they may be removed for cosmetic reasons. Congenital anomalies caused by incomplete closure of the first branchial cleft occur as clefts, cysts, and tracts in and about the ear. The anomalies have been classified as types 1 and 2 depending on their location and composition. These lesions usually present in infancy and childhood but may first be diagnosed in adults. They are found in the external auditory canal from the eardrum to the junction of the tragus and antitragus.
Pathologic Features
The cysts and tracts are lined predominantly by squamous epithelium with varying admixtures of respiratory and mucinous epithelium. Type I anomalies are cystic and entirely ectodermal without skin adnexa or cartilage; type II anomalies are composed of skin with adnexal structures and cartilage, and can involve the drum and middle ear. The fistulas, cysts, and sinuses extend inferiorly into an area bounded by the hyoid bone, sternocleidomastoid muscle, and mandible, and deeply to involve the parotid gland and facial nerve ( Fig. 12.2 ). These lesions are not usually associated with other facial malformations.
Differential Diagnosis
Differential diagnoses will vary with the age of the patient. In infants, cystic hygromas are not localized lesions. In adults, tumors of the parotid gland and adjacent lymph nodes can be cystic. The lymphoepithelial cyst of the parotid gland or lymph node is a well-defined lesion in patients infected with human immunodeficiency virus 1 (HIV-1). The cysts are lined with nonkeratinizing squamous epithelium typical of a branchial anomaly ( Fig. 12.3 ). Warthin tumors are frequently cystic. However, the oncocytic lining epithelium characteristic of Warthin tumor is not seen in the branchial anomaly. Imaging studies are needed for the diagnosis of lesions of the parotid gland and temporomandibular joint, which can present as masses anterior or posterior to the tragus (see subsequent discussion).
Treatment and Prognosis
Type I anomalies can be simply excised but occasionally require superficial parotidectomy and facial nerve dissection. Adequate treatment of type II anomalies requires surgical excision of the skin and surrounding cartilage of the external auditory canal with superficial parotidectomy and facial nerve dissection. These lesions should not recur if they are completely excised.
Epidermal Cysts of the Skin
Epidermal cysts of the pinna may be congenital (dermoid), acquired (traumatic keratinous epidermal inclusion), or cystic hair follicle tumors ( Fig. 12.4 ). These are not sebaceous cysts; they contain keratin, not sebum.
Congenital dermoid cysts of the skin are found in lines of closure near the ears, eyes, nose, and cheeks. The dermoid cyst is lined with epidermal squamous cells containing keratohyalin granules and surrounded by normal accessory hair follicles and glands. Similar keratinous cysts lacking surrounding hair follicles and glands may be found anywhere on the pinna and are called keratinous epidermal cysts (see Fig. 12.4A ).
The pilar cyst (wen) is a benign cystic neoplasm derived from the hair shaft epithelium and characterized by a lining squamous epithelium that lacks keratohyalin (see Fig. 12.4B ). Variants include pilomatricoma (Malherbe calcifying epithelioma; see Fig. 12.4C ) and cystic trichilemmoma (see Fig. 12.4D and E ). These hair shaft tumors are often located at or in the external meatus.
Treatment and Prognosis
Simple excision is curative, but ruptured cysts can incite an extensive foreign body granulomatous reaction to keratin squame and hair.
Cartilaginous Pseudocyst
Clinical Features
Cartilaginous pseudocyst, or idiopathic cystic chondromalacia, of the auricular cartilage presents as a painless diffuse mass in the concha of the upper half of the auricle. This is likely a heterogeneous group of lesions representing congenital dysplasia of the cartilage in infants and traumatic pseudocysts in children and adults.
Pathologic Features
Biopsy is rarely performed but will yield fragments of cartilage lacking any cellular lining.
Differential Diagnosis
The clinical differential diagnoses of relapsing polychondritis, chondrodermatitis nodularis helicis, and traumatic perichondritis can be disregarded by the absence of pain and inflammation. Histologic examination eliminates vascular or cartilaginous neoplasms, but clinical presentation and location are characteristic.
Treatment and Prognosis
Treatment varies from aspiration of oily serous fluid to oral administration of steroids.
Traumatic Injury
Clinical Features
The auricle is the site of traumatic injury varying from direct physical damage resulting in extensive scarring (cauliflower ears) of the pinna to keloid formation in the earlobes.
The earlobes produce most of the traumatic material removed and sent to the pathology service. Keloid, an overgrowth of broad bands of dense sclerotic scar tissue, commonly occurs in lobes after ear piercing ( Fig. 12.5 ). Metallic pigmentation, argyria, the deposition of silver, and sarcoid-like allergic contact granulomas also occur.
Granuloma (acanthoma) fissuratum, or spectacle frame acanthoma, is a traumatic deformity of the pinna caused by the pressure of tight eyeglass frames that scar and groove the posterior aspect of the pinna. Histologically, there is a central hyperkeratotic plug that is driven down to cartilage, a pattern similar to chondrodermatitis helicis (see later discussion), but the location and history are specific.
Xanthogranuloma and Granulomatous Inflammation
Clinical Features
Xanthogranulomas are nodules in the skin of neonates, infants, and adults that are characterized histologically by large foamy macrophages (xanthoma cells). Their natural history and age distribution suggest that they are not neoplasms but reactive developmental/metabolic or inflammatory lesions. Ear piercing and the stimulus of foreign material are also implicated in the etiology of xanthogranuloma.
A Massachusetts General Hospital series of 34 cases had a male-to-female ratio of 4:1. The ages ranged from birth to 50 years, with peaks at younger than 1 year and between 20 and 30 years of age. Juvenile xanthogranuloma in infancy is more often multiple, with rare visceral involvement reported; most will involute by the end of the first year of life. The adult form, in adolescents and young adults, tends to be localized to the earlobe.
Pathologic Features
Histologically, both juvenile and adult types are composed of foamy histiocytes (xanthoma cells), multinucleated (Touton) giant cells, lymphocytes, and eosinophils ( Fig. 12.6 ) organized in recognizable patterns (xanthogranulomatous, xanthomatous, fibrohistiocytic, and combinations) that have no relationship to the clinical outcome. The xanthoma cells and Touton giant cells contain lysozyme but not S100 protein, which suggests that they are of macrophage/monocyte origin and not of dendritic cell origin.
Differential Diagnosis
The differential diagnosis includes infections due to mycobacteria (leprosy as well as tuberculosis and other related mycobacteria), fungi, and parasites, which will require the use of acid-fast and other tissue stains and cultures. Infectious diseases endemic in the Middle and Near East and Latin America are now seen in Europe and North America due to the ease of population movements and military incursions. Leishmaniasis, a protozoan infection spread by the bite of the sandfly, causes visceral and mucocutaneous syndromes depending on the species of the parasite and the immunocompetence of the infected individual. In Mexico, infection with the parasite Leishmania mexicana causes a characteristic solitary ulcerating skin nodule on the pinna known as Chiclero’s ulcer. Leishmania organisms (amastigotes) can be found in dermal granulomatous inflammation in skin tissues and smears obtained from scrapings, fine-needle aspirates, and biopsies with hematoxylin and eosin and Wright’s stains. However, amastigotes are scarce in histologic sections from mucosal leishmaniasis (espundia), and immunofluorescent antibody or polymerase chain reaction testing of tissues can enhance detection. Mucosal leishmaniasis is species specific (caused by Leishmania viannia braziliensis ) and is endemic in Brazil. Speciation is achieved by culture on medium available from the Centers for Disease Control and Prevention.
Dendritic cell proliferations (Langerhans cell histiocytosis) are CD1a, S100 protein, and langerin positive. Granular cell tumor is a dermal tumor composed of infiltrating cells of Schwann cell origin that have a granular cytoplasm and benign central nuclei ( Fig. 12.7 ). Unlike xanthogranuloma, extensive pseudoepitheliomatous hyperplasia of the overlying epidermis frequently occurs (see later discussion). Granular cell tumors may be found in multiple skin sites.
Treatment and Prognosis
Because xanthogranuloma can spontaneously involute by 1 year of age, no treatment is recommended in infants. For persistent childhood lesions and those in adults, local excision is appropriate for cosmesis, deformity, or loss of function. Children with both xanthogranuloma and neurofibromatosis are at risk of the development of chronic myelogenous leukemia.
The infectious granulomatous diseases require identification of the causative agent and appropriate antibiotic therapy.
Inflammatory Lesions
The exposure of the helix of the pinna to both sun and cold results in a variety of inflammatory, reactive, and neoplastic lesions that are clinically similar and require biopsy for differentiation. Overwhelmingly, the most common pinna lesions seen in surgical pathology practice (see Tables 12.1 and 12.2 ) are basal cell carcinomas and squamous proliferative lesions of actinic etiology ranging from keratoses to squamous cell carcinoma. The inflammatory lesions discussed subsequently can mimic actinic malignancies clinically and often histologically owing to pseudoepitheliomatous hyperplasia of the reactive squamous epithelium.
Chondrodermatitis Helicis (Nodularis)
Clinical Features
Chondrodermatitis helicis (nodularis) is a crusted, ulcerated painful nodule on the helix (less often the antihelix) of older men (mean age, 60 years; range, 31–82 years). It is twice as common in men as in women. Patients relate a long history (1 month to 25 years) of pain, often exacerbated by cold. The disease is attributed to pressure trauma, poor vascularization of the pinna, and collagen damage from the sun and cold. The size of the lesions is often not recorded in the cited papers, but lesions may be as large as 1 cm in diameter in situ.
Pathologic Features
Histologically, there is skin ulceration with a benign reactive hyperplastic epidermis, with hyperkeratosis and/or parakeratosis, acute and chronic inflammation, and dermal scarring with granulation tissue. Necrobiosis of collagen extends to the subjacent cartilage ( Fig. 12.8 ). The necrotic tissues are sloughed through the ulcerated skin surface, a process described as a perforating dermatitis.
Differential Diagnosis
Clinical differential diagnosis includes ulcerating squamous or basal cell carcinoma, which occurs in the same age group and location. There is usually no other associated disease of cartilage, but a similar lesion has been described in systemic sclerosis.
Other nodular lesions located on the helix such as elastic or weathering nodules, dystrophic calcification, and calcified cartilage clinically resemble chondrodermatitis and are associated with trauma or actinic or cold exposure. The calcified cartilage can ossify, forming a rigid, petrified auricle.
Treatment and Prognosis
Irrespective of local therapy (excision, topical and injected steroids, laser, or electrocautery), as many as 30% of chondrodermatitis lesions recur.
Amyloidosis
Amyloid derived from actinically injured keratinocytes can accumulate as pink globular material (lichen amyloidosis) in the papillary dermis. The Congo red stain, which imparts the characteristic light microscopic orange hue to the amyloid, is apple green when viewed through polarizing filters. Cutaneous amyloidosis in patients undergoing associated chronic dialysis can occur in the pinna and external auditory canals.
Pernio (Chilblains)
Clinical Features
Localized painful, erythematous, inflammatory nodules, known as pernio or chilblain, result from exposure to a cold, but above freezing, humid environment, which exacerbates heat loss. Pernio occurs equally in men and women, with a mean age of 48 years (range, 10–75 years). It may be primary and idiopathic with a positive antinuclear antibody test and not associated with other concurrent disease. Pernio associated with other diseases and cold exposure is considered to be secondary. Pernio-like lesions (mimics) also occur in other autoimmune diseases in the absence of cold exposure.
Pathologic Features
Histologically, pernio and its mimics are characterized by dermal angiocentric lymphocytosis, papillary edema, and lymphocytic exocytosis involving rete pegs and sweat glands.
Differential Diagnosis
Patients with systemic or extracutaneous autoimmune disease such as systemic lupus erythematosus, viral hepatitis, rheumatoid arthritis, cryofibrinogenemia, and hyperglobulinemia may present with secondary perniosis, but show “frequent vascular fibrin deposition involving reticular dermal vessels.” In addition to these histologic characteristics, histiocytic infiltrates and noncaseating granulomas signify secondary pernio and require appropriate cultures and tissue stains. Patients with iritis, rheumatoid arthritis, or Crohn disease can show giant cell vasculitis and a granuloma annulare–like tissue reaction.
Treatment and Prognosis
Protection from cold exposure and treatment of underlying disease are required in susceptible individuals.
Gout
Urate crystals deposit in the skin of the helical edge as gouty tophi ( Fig. 12.9A ). Both gout and pseudogout (calcium pyrophosphate) can affect the temporomandibular joint and present as a painful, inflamed preauricular mass.
Pathologic Features
The clinical diagnosis can be confirmed by needle aspiration of the lesion with demonstration of the characteristic needle-like urate crystals with polarizing filters (see Fig. 12.9B ). The aspirate and surgical specimens should be fixed in alcohol to preserve the water-soluble urate crystals. The rhomboid pyrophosphate crystals of pseudogout are insoluble in aqueous fixatives and will remain in processed tissues.
Perichondritis
Perichondritis is a diffuse infiltrate of inflammatory or neoplastic leukocytes in the skin of the external ear. Acute malignant perichondritis in individuals with diabetes due to Pseudomonas infection is very destructive and infiltrative, with rapid involvement of the parotid gland and facial nerve, external auditory canal, and middle ear, and then temporal bone and brain invasion.
Neutrophilic eccrine hidradenitis, an acute inflammatory infiltrate of eccrine glands in patients undergoing chemotherapy for malignancy, can present with swollen inflamed ears. Acute myeloid leukemia, B- and T-cell lymphomas, and acquired immune deficiency syndrome (AIDS)–related non-Hodgkin lymphoma can present as auricular perichondritis.
Relapsing Polychondritis
Clinical Features
Relapsing polychondritis is a systemic autoimmune disease of type II collagen occurring equally in affected men and women, with a median age of 47 years (range, 17–86 years). Floppy ears and saddle nose are dramatic effects of cartilage destruction, and almost 50% of patients have hearing impairment due to inner ear damage. Disease of the eyes is common, and one-fourth to one-third of patients die of cardiovascular system or respiratory tract involvement. Bilateral auricular chondritis that undergoes spontaneous resolution, but recurs, is characteristic of the disease.
Pathologic Features
Acutely, patients have diffuse, bilateral, painful erythematous auricles. The cartilage and perichondrium are necrotic and inflamed and, with healing, are replaced by scar tissue with loss of structural support. The severity of the disease is directly related to levels of antibody to type II collagen and deposition of immune complexes and complement in cartilage.
The disease is associated with patients having human leukocyte antigen-DR isotype 4, and approximately one-third of patients also have associated systemic lupus erythematosus or rheumatoid arthritis. Relapsing polychondritis can be a paraneoplastic syndrome that precedes the onset of myelodysplasia.
Treatment and Prognosis
Systemic steroid therapy modifies the acute disease and reduces the frequency and severity of episodes but does not prevent recurrence of the disease.
Neoplasms
Neoplasms of the ear are rare: only one in 10,000 patients with ear symptoms has an ear malignancy. Clinically, tumors present similarly, either as an actinic lesion on the helix or as a mass in the external auditory canal or middle ear. All require biopsy for differentiation. Squamous cell carcinoma and basal cell carcinoma, the most common ear neoplasms (80%–90% of all ear tumors), are found in approximately equal numbers (see Table 12.1 ).
Basal Cell Carcinoma
Clinical Features
Basal cell carcinoma is mainly a lesion of the auricular helix. There is a male predominance with a mean age at diagnosis of 60 years.
Pathologic Features and Differential Diagnosis
Basal cell carcinomas, which rarely occur at the external auditory meatus and extend into the canal, must be differentiated from adenoid cystic carcinoma. Basal cell carcinoma will invariably arise from the overlying skin and maintain areas of typical picket-fence basal epithelium with spindle cell or squamous differentiation ( Fig. 12.10 ). Adenoid cystic carcinoma arises from subsurface squamous epithelium and is composed of organoid aggregates of uniformly small basaloid cells with little cytoplasm or differentiation and the characteristic cribriform pattern.
Treatment and Prognosis
Local excision suffices for auricular lesions. Metastases and death are uncommon. Within the canal, delay in diagnosis and deep invasion by the tumor can necessitate partial temporal bone resection for adequate removal.
Squamous Cell Carcinoma
Clinical Features
The origins, clinical manifestations, sex distribution, treatment, and prognosis of squamous cell carcinoma differ depending on the site of origin: the pinna or the external auditory canal.
Lesions of the pinna are associated with actinic injury and occur in men older than 70 years of age who have had many actinic keratoses or squamous cell carcinomas removed from the exposed skin of the head and neck.
Squamous cell carcinoma of the external auditory canal is more insidious in its presentation than that of the pinna. There is a female preponderance with a mean age of 60 years, a decade earlier than in patients with squamous cell carcinoma of the pinna. Symptoms, often present for less than a year, include drainage, pain, and hearing loss, indicating an extensive, invasive lesion.
Pathologic Features
Squamous cell carcinoma is characterized by proliferation of squamous cells with abnormal cytologic manifestations of malignancy and abnormal keratinization (dyskeratosis). Basal-squamous lesions, tumors with histologic characteristics of both basal cell and squamous cell carcinoma, are not unusual (see Fig. 12.10 ).
Differential Diagnosis
Squamoproliferative lesions of the skin of the pinna include reactive pseudoepitheliomatous hyperplasia, fibroepithelial papillomas (skin tags), warts (verruca vulgaris), actinic (solar or senile) keratoses, and in situ (Bowen’s disease) and invasive squamous (epidermoid) carcinoma in all its guises. Well-differentiated lesions mimic reactive hyperplasia (see later discussion).
Keratoacanthoma is a distinct clinicopathologic entity simulating well-differentiated squamous cell carcinoma. The proliferative lesion grows quickly, forming a cup shape with a central core of keratin ( Fig. 12.11 ). The surrounding proliferating, well-differentiated squamous epithelium has an indistinct basement membrane and can seem to be invasive. These lesions will atrophy and expel the central keratin. It is important, however, to warn the surgeon that absolute histologic differentiation from squamous cell carcinoma is not ensured (many observers consider it to be a well-differentiated variant of squamous cell carcinoma), and, therefore, the lesion must be completely excised.
Spindle cell (sarcomatoid) squamous cell carcinoma requires differentiation from other spindle cell neoplasms (melanoma, fibroxanthoma, and other mesenchymal tumors) with immunohistochemical studies ( Fig. 12.12A and B ; see later discussion).
Treatment and Prognosis
Local excision of pinna lesions usually suffices for local control, but residual or recurrent disease still occurs in 25% of patients. Approximately 10% of invasive squamous cell carcinomas metastasize to regional lymph nodes; patients with such metastases can be treated with neck dissection. Even with reported poor control and clinical persistence, death is usually due to other intercurrent disease.
In the external auditory canal, in response to chronic irritation, pseudoepitheliomatous hyperplasia can simulate a well-differentiated squamous cell carcinoma. If the patient presents with symptoms and signs of pain and bloody ear discharge lasting longer than 2 months with an ulcerated ear mass, a diagnosis of carcinoma is likely. If there is no pain and the ear discharge has taken place over a period of less than 2 months, the lesion should be treated conservatively with antibiotics. If after 2 to 3 weeks no resolution has occurred, the lesion should be excised with a border of normal tissue and a carcinoma should be excluded by histopathologic examination.
Spread of the external auditory canal tumors depends on the location within the canal: anteriorly, invasion through the cartilaginous canal extends to the parotid gland and lymph nodes; posteriorly, adjacent to the bony canal, spread is into the postauricular space and medially into the middle ear. Squamous cell carcinomas of the canal metastasize to regional nodes more frequently than do pinna lesions, but the 5-year tumor-related death rate of approximately 50% is due to local invasion rather than metastases.
Treatment for invasive squamous cell carcinoma of the canal is temporal bone resection (partial, total, or piecemeal), depending on the extent of the tumor. The defect is covered with a skin or muscle flap and is postoperatively irradiated. This treatment is associated with a 50% 5-year survival rate in several series.
Malignant Melanoma
Clinical Features
Malignant melanoma, although relatively rare, is the third most common malignancy of the external ear, accounting for 7% to 16% of all head and neck melanomas. As with the other actinically related neoplasms, squamous and basal cell carcinomas, there is a 2:1 male-to-female ratio with a mean age at diagnosis of 72 years.
Pathologic Features
Malignant melanoma is one of the great mimics among neoplastic lesions. It can be pigmented or amelanotic, ulcerated or nodular, and, histologically, simulate epithelial or mesenchymal neoplasms (see Fig. 12.12C and D ). When presented with a poorly differentiated epithelioid or sarcomatoid neoplasm, one must always consider melanoma, and immunohistochemical studies should be done to rule it out.
Melanoma arises in a preexisting nevocellular lesion of the skin or mucous membrane, and junctional change should be identified to differentiate primary from metastatic melanoma. Excisional biopsies of skin nevocellular lesions that had previously undergone biopsy may have hemosiderophages and myofibroblasts (scar), partially or completely replacing the original lesion. Iron and trichrome staining or vimentin or actin expression (reactive) and S100 protein, SOX10, and/or HMB-45 expression (melanoma) distinguish between scar and spindle cell melanoma.
Treatment and Prognosis
Treatment varies depending on the location on the ear: peripheral pinna lesions undergo wide local excision or amputation; more central lesions, adjacent to or involving the external auditory meatus, require much more extensive surgery including partial temporal bone resection. Prognosis is related to depth of invasion. Seven of the 16 cases reported by Davidsson and colleagues were nodular, and depth of invasion varied from 0.15 to 11.5 mm; nine of the 16 were Clark level IV or V at diagnosis. All patients had wide excision, but of the four (25%) who died, three did so within 1 year of diagnosis. Prophylactic neck dissection, including superficial parotidectomy, is deemed appropriate only for Clark level IV or V lesions.
Dermatofibroma (Fibrous Histiocytoma)
Clinical Features
Dermatofibromas are benign polymorphous cutaneous tumors to which several names have been applied: subepidermal nodular fibrosis, dermatofibroma, fibroxanthoma, and sclerosing hemangioma, as well as fibrous histiocytoma. Dermatofibroma is a more appropriate term than fibrous histiocytoma because the predominating spindle cells are not histiocytes. These painless lesions are typically found in the upper dermis of the extremities in adults.
Pathologic Features
They are poorly circumscribed, usually with infiltrating margins, and are composed of spindly mononuclear or multinuclear cells with amphophilic cytoplasm that are classically arranged in a storiform pattern. Epidermal hyperplasia frequently overlies the lesion. Variable numbers of foamy macrophages and Touton giant cells are present. Birefringent collagen is surrounded by spindle cells at the periphery of the lesion. Various modifying adjectives are applied to fibrous histiocytomas depending on the mixture of cell types, vascularity, and hemosiderin in the lesion: angiomatoid, epithelioid, giant cell, or cellular.
Differential Diagnosis
In 1964, Kempson and McGavran described a “histologically ‘malignant’ but biologically benign lesion of the skin” to which they applied Helwig’s term “atypical fibroxanthoma.” The well-circumscribed ulcerated nodular lesions occurred in the sun-exposed skin of 21 patients: 15 men, 6 women; mean age, 67 years; range, 52–86 years. Five of the lesions occurred on the ear.
The atypical fibroxanthomas are composed of intermixed cell types, fusiform to round cells with variable numbers of giant cells (see Fig. 12.12E and F ). There is remarkable variability in nuclear and nucleolar size and shape, but mitotic activity is low at 1 per 10 high-power fields. The cellular and nuclear pleomorphism resulted in the initial pathologic diagnoses in the 21 cases: sarcoma in 10, carcinoma in 4, melanoma in 1, and atypical fibroxanthoma in 6. However, the lesions do not recur when they have been adequately locally excised and act in an otherwise benign fashion.
Recently, three cases of an atypical fibroxanthoma variant were described in which osteoclast-like giant cells were dispersed within the tumor. Twenty percent of 74 cases of another variant of fibroxanthoma, benign cellular fibrous histiocytoma described by Calonje and colleagues, occurred in the head and neck, including three cases in the external ear. This lesion typically occurs in young men (2:1 male-to-female ratio; mean age, 33 years; range, 9 months to 86 years) and has ill-defined margins with extension into the deep reticular dermis. Eosinophilic spindle cells with a mean mitotic rate of three per high-power field dominate, but there is an admixture of spindle cells, giant cells, and foam cells. The pleomorphism of the atypical fibroxanthoma is not present but a focal storiform pattern, epidermal hyperplasia, and peripheral hyalinized collagen bundles found in dermatofibroma are present. Although 26% of these lesions recurred within 3 years after inadequate excision, none metastasized.
The atypical fibroxanthoma must be differentiated from the actinic malignancies that it mimics by its pleomorphism: spindle cell (sarcomatoid) squamous cell carcinoma and melanoma. Each entity has unique ultrastructural characteristics. Squamous cell carcinoma has desmosomes and intracellular keratin; melanoma has melanosomes and premelanosomes; fibrous histiocytoma has myofilaments characteristic of myofibroblasts. A battery of immunohistochemical stains can aid in the differentiation of these spindle cell neoplasms ( Table 12.3 ). Squamous cell carcinoma expresses cytokeratins; melanoma expresses S100 protein, SOX10, and HMB-45; atypical fibroxanthoma expresses muscle-specific actin, vimentin, α 1 -antitrypsin/antichymotrypsin, and macrophage lineage markers such as KP-1 (see Fig. 12.12 ). Fibrous histiocytomas are negative for desmin (thus differentiating them from smooth muscle tumors, which contain both smooth muscle actin and desmin) and are usually immunoreactive to macrophage-monocyte markers such as KP-1. Strong LN-5 (CD74) immunoreactivity is reported in malignant fibrous histiocytomas and large atypical fibrous histiocytomas with subcutaneous extension, but not in superficial atypical fibroxanthoma.
Table 12.3
Differential Immunocytochemical Staining of Spindle Cell Tumors of the Pinna
| KERs | EMA | S100 | HMB-45 | KP1 | α1AT | ACT | DES | VIM | |
|---|---|---|---|---|---|---|---|---|---|
| Squamous cell carcinoma | + | + | - | - | - | - | - | - | - |
| Malignant melanoma | - | - | + | + | - | - | - | - | - |
| Fibrous histiocytoma | - | - | - | - | + | + | + | - | + |
| Nodular fasciitis | - | - | - | - | + | ? | + | - | + |
| Leiomyoma | - | - | - | - | - | - | + | + | + |
α1AT, α 1 -Antitrypsin and/or chymotrypsin ; ACT, muscle-specific actin ; DES, desmin ; EMA, epithelial membrane antigen ; HMB-45, human melanoma B-45 protein ; KERs, keratins ; KP1, macrophage/monocyte lineage marker ; S100, S100 protein ; VIM, vimentin.
Treatment and Prognosis
As clinicopathologic entities, these fibrous lesions differ in patient population, histologic appearance, and propensity for local recurrence if they are not adequately surgically excised.
Nodular Fasciitis
Clinical Features
Nodular fasciitis is a benign neoplasm of myofibroblasts. Patients present with a rapidly growing mass that involves the skin adjacent to the ear, pinna, or external auditory canal. Some patients report a preceding traumatic insult. Most of the lesions seem to be well circumscribed. Half of the cases reported by Thompson and colleagues were dermal; the remaining cases were subcutaneous or could not be separated between dermal and fascial location. Nodular fasciitis in the ear canal is often ulcerated and bleeds. Patients are approximately equally divided between men and women, with a mean age of 27 years (range, 1–76 years), a population similar to that of fibrous histiocytoma described earlier.
Pathologic Features
Histologically, the lesion is characterized by spindle-shaped myofibroblasts loosely aggregated in a nodular storiform pattern with adjacent hypocellular myxoid areas, acellular keloid-like collagen, and rare giant cells ( Fig. 12.13 ). Not unexpectedly, spindle cells react with myofibroblast markers vimentin, actin, and KP-1. Mitotic figures are readily identifiable, reflecting the rapid growth noted clinically, but atypical forms are not seen.
Treatment and Prognosis
The preferred form of therapy is adequate local surgical excision of the lesion. This can be difficult in or around the ear with attempts to maintain cosmesis. Recurrence is infrequent, occurring in only 1% to 2% of patients.
Myxoma (Carney Complex)
Clinical Features
Myxomas of the external ear involve both the pinna and the canal in a rare familial autosomal dominant syndrome known as the Carney complex. Patients have myxomas, spotty pigmentation, endocrine tumors, and schwannomas. The lesions occur equally in males and females, with ages ranging from birth to 41 years (mean, 19.3 years).
Pathologic Features
Histologically, polypoid or sessile myxomas occurring on the pinna or in the canal are composed of a bland myxomatous stroma and a proliferating, often basaloid, surface squamous epithelium.
Differential Diagnosis
As a consequence of the latter, differential diagnoses based on superficial biopsies may range from squamous papilloma to epidermal inclusion cyst, trichoepithelioma, and basal cell carcinoma. Any myxomatous lesion on or in the ear of an infant or young child also requires consideration of RMS (see later discussion).
Treatment and Prognosis
Myxomas are treated with wide local excision. Recurrences, which are frequent, can be reexcised; they do not metastasize. When myxoma is diagnosed, the clinician should be alerted to the possibility of the Carney complex because of the occurrence of potentially fatal cardiac myxomas. Recognizing that the Carney complex includes both cardiac and aural myxomas, reports of myxoma from the cardiac atrium metastasizing to the temporal bone should be regarded with some skepticism.
Merkel Cell Carcinoma (Cutaneous Neuroendocrine Carcinoma)
Clinical Features
Merkel cell carcinoma is a malignant neuroendocrine small cell neoplasm found in the skin of elderly (1.5:1 male-to-female ratio; average age, 70 years) or younger immunosuppressed individuals. Merkel cell tumors are predominantly located in the head and neck (face, oral, and nasopharyngeal mucosa; 47%) and trunk (40%). However, only 20 cases arising on the auricle were found by Rinaldo and colleagues in their literature review. The origin of the tumor in either hair follicle mechanoreceptor Merkel cells or scattered stem cells in oral mucosa, epidermis, and dermis is under debate. Although the tumor’s exact cell of origin and pathogenesis are unknown, Merkel cell polyomavirus (MCPyV) and ultraviolet radiation are associated with the development of Merkel cell carcinoma
Pathologic Features
The tumor is composed of sheets and aggregates of undifferentiated small cells that fill the dermis ( Fig. 12.14A ). Ultrastructural characteristics of the tumor cells include perinuclear keratin fibrils, peripheral cytoplasmic dense core granules, and zona adherens intercellular junctions.
Differential Diagnosis
Immunohistochemistry is a major aid in diagnosis, with a dot-like perinuclear keratin staining pattern (see Fig. 12.14B ), and cytoplasmic and membrane expression of chromogranin and synaptophysin differentiating this tumor from lymphoma, poorly differentiated carcinoma, and melanoma. CK20 (a low-molecular-weight cytokeratin with expression restricted to the gastrointestinal tract and urinary tract epithelium) positivity in the majority of tumor cells also strongly supports a diagnosis of Merkel cell carcinoma. MCPyV, a double-stranded DNA virus, is monoclonally integrated in approximately 80% of Merkel cell carcinomas. The frequency of MCPyV exposure and the rarity of Merkel cell carcinoma suggest that other cellular events likely contribute to the development of the disease. MCPyV can be detected by polymerase chain reaction targeting the Large T (LT) antigen- encoding sequence coding gene or by immunohistochemistry using CM2B4, a monoclonal antibody against the antigenic epitope ( Fig. 12.14A ). Rarely, a small cell carcinoma of the lung will metastasize to the ear region. CK20 expression by the tumor cells eliminates this differential diagnosis because small cell carcinomas, with the exception of a salivary gland primary, do not express this marker.
Treatment and Prognosis
This aggressive malignant tumor acts more like small cell carcinoma than carcinoid. Recurrences are common (41%–62%) despite wide local excision. Metastases to regional lymph nodes (52%) and distant sites (34%) occur despite therapeutic lymph node resection, irradiation, and chemotherapy. The reported 5-year survival rate ranges from 40% to 68% of patients, with immunosuppressed patients doing relatively less well. The patterns of lymph node spread and risk of recurrence are similar to those of melanoma. Sentinel node dissection is a predictor of regional lymph node recurrence and metastases. The use of keratin immunohistochemical studies is recommended in evaluating lymph nodes for metastases.
Mucinous (Colloid) Carcinoma
Primary mucinous (colloid) carcinoma of the skin is a rare neoplasm having a propensity for the skin of the face and neck and homologous to mucinous carcinoma of the breast. Of 37 reported cases presenting as a solitary nodule, 3 were found in the external ear helix and lobe and 1 in the retroauricular skin. There is a 2:1 female-to-male predominance, with age ranging from 31 to 89 years (mean, 65 years; median, 67 years). Histologically, the tumor is composed of nests of malignant cells in pools of mucin, either as pure mucinous carcinoma or mixed with ductal carcinoma in situ, atypical ductal hyperplasia, or ductal hyperplasia. Signet ring–type cells are very uncommon. Wide local excision, including reexcision of recurrences, appears to be adequate treatment.
Kaposi Sarcoma and Bacillary Angiomatosis-Peliosis (Bartonellosis)
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