Non-Neoplastic Lesions of the Ear and Temporal Bone

Clinical Features

Work type I branchial cleft anomalies usually manifest as periauricular cysts, rather than sinuses or fistulas. They are usually located anterior, inferior, or posterior to the conchal cartilage and pinna; if a sinus tract is present, it parallels the external auditory canal. Although most are discovered in childhood, some are not diagnosed until adulthood, when they are often misdiagnosed as epidermal inclusion cysts or as abscesses, in cases of secondary infection. Incision and drainage by itself results in persistence or recurrence over years.

Work type II branchial cleft anomalies, more common than type I, usually come to medical attention in the first year of life as a result of a draining sinus tract with otorrhea or periauricular drainage rather than as a cyst; the lesions are frequently infected at the time of diagnosis. They may present as a mass with a sinus or a fistulous tract between the neck and the ear canal ( Fig. 17.1 ). A sinus may open from a fistulous track, usually anterior to the sternocleidomastoid muscle and superior to the hyoid bone, or in the external auditory canal. The spatial relationship to the facial nerve is variable, requiring a cautious surgical approach (see Fig. 17.1 ).

Females are affected twice as often as males. A careful physical examination with particular attention to the periauricular region and lateral neck is essential, including otologic examination to exclude a tract which communicates with the external auditory canal or rarely, the middle ear space. High-resolution, contrast-enhanced computed tomography (CT) is the preferred radiographic study for accurate delineation of the extent and course of the anomaly prior to surgery, where they are classified based on “anatomic site” (Arnot classification system).

Pathologic Features

Microscopic Findings

The cysts, sinuses, and fistulas may be lined by either stratified squamous epithelium or ciliated respiratory epithelium ( Fig. 17.2 ). The cyst wall may contain lymphoid aggregates, sometimes with germinal centers ( Fig. 17.3 ), as commonly seen in second branchial cleft anomalies. If the lesion is infected, the epithelium may be largely denuded, replaced by heavily inflamed granulation tissue. Type II anomalies are distinguished by the presence of cutaneous adnexal structures and cartilage ( Fig. 17.4 ), the result of a mesodermal component in their development. These lesions are p16 negative.

Differential Diagnosis

The pathologic differential diagnosis includes epidermal inclusion cyst, cholesteatoma, benign lymphoepithelial cyst, folliculitis/abscess, accessory tragus, chondrocutaneous vestige, and, in adults, cystic metastatic squamous cell carcinoma. Epidermal inclusion cysts and cholesteatomas contain intracystic keratinous debris. However, without clinical or imaging information, an epidermal inclusion cyst in this anatomic site may be histologically identical. A lymphoepithelial cyst lacks a sinus/fistula. Folliculitis is centered on a follicle and dermis based. An accessory tragus recapitulates the external auricle, showing a central core of cartilage without a cyst. A chondrocutaneous vestige develops at the anterior border of the sternocleidomastoid muscle, usually in lower third of the neck, and has a cartilaginous core without a cyst. The benign cytologic features of branchial cleft anomalies contrasts with the atypia and loss of polarity encountered in cystic metastatic squamous cell carcinoma . These metastases usually develop in the jugulodigastric region and not within the area of a first branchial cleft anomaly. Performing p16 immunohistochemistry can help to confirm an oropharyngeal primary, but patchy strong reactivity may be seen in the epithelial cells immediately adjacent to lymphocytes within the epithelium.

Prognosis and Therapy

First branchial cleft anomalies are benign congenital lesions, commonly given to secondary infection. Treatment consists of complete surgical excision of the malformation, including cysts, and any associated sinus or fistula. In some cases, superficial parotidectomy may be required for complete removal. Complications of surgery may be seen.

Clinical Features

Cystic chondromalacia tends to be more common in young males (mean, 35 years), with a 9 : 1 male to female ratio, although either sex and all ages may be affected. An increased incidence has been noted in Chinese and Malay males, although cystic chondromalacia has been reported in patients of all racial backgrounds. The typical presentation is a unilateral, fusiform, slightly fluctuant swelling of the helix or antihelix (scaphoid fossa) ( Fig. 17.5 ). The lesion is painless, and there are no changes in the overlying skin.

Pathologic Features

Gross Findings

If the full thickness of the cartilaginous plate has been excised, a central, slit-like cleft can be seen in the cartilage ( Fig. 17.6 ). When incised, the cyst exudes viscous, clear to olive oil–colored fluid, usually less than 2 mL in volume. The cystic area, especially in long-standing lesions, may be lined by a thin brown-tinged layer, representing old hemorrhage and granulation tissue, or may be completely replaced by fibrosis (there is no epithelial lining). Often the specimen is fragmented, especially if the cyst is “unroofed” ( Fig. 17.7 ), making prior knowledge of the clinical appearance helpful for diagnosis.

Microscopic Findings

The cartilaginous plate contains a central cleft with no epithelial lining, hence the term “pseudocyst.” The contour of the cleft may be slightly irregular, and a thin inner rim of fibrous tissue or granulation tissue with plump fibroblasts may be seen ( Figs. 17.6–17.8 ). Hemosiderin deposits may be present. In long-standing cases the fibrous tissue may obliterate the cystic space.

Differential Diagnosis

Cystic chondromalacia is easily distinguished from relapsing polychondritis by its lack of an inflammatory component, and from chondrodermatitis nodularis helices by the normal skin overlying it. Both of these lesions are associated with pain. Traumatic perichondritis usually shows acute inflammation without a cyst.

Prognosis and Therapy

Cosmetic concerns for this benign lesion often prompt therapeutic intervention. Treatment is usually directed at extirpation of the pseudocyst while preserving the underlying architecture of the cartilaginous plate. Incision and drainage with curettage has had variable success. Needle aspiration alone has limited value but is quite effective when combined with compression suture therapy using “button” bolsters. Unroofing of the pseudocyst by removal of its anterior wall followed by application of a sclerosing agent, or by suture compression, has the lowest incidence of recurrence.

Clinical Features

CDNH presents as an exquisitely painful nodule, usually on the helix or antihelix; however, it may develop on any portion of the auricle. Lesions of the helix are twice as common as those of the antihelix. CDNH begins as a reddish, round, indurated nodule, measuring several millimeters in diameter; over a period of days to a few weeks, the nodule develops a central crater, which contains crust-like material ( Fig. 17.9 ). CDNH is more common in males; however, lesions of the antihelix are more common in females. Most patients are in the sixth decade. Cell phone–induced injury seems to be an etiologic factor.

Pathologic Features