Benign Neoplasms of the Ear and Temporal Bone

Clinical Features

Ceruminous adenoma accounts for less than 1% of all external ear tumors, usually affecting middle-aged (mean, 55 years) patients, without a sex difference. Patients usually present with a mass in the posterior wall of the outer one-third to one-half of the EAC. There may be associated pain, hearing loss (sensorineural and conductive), tinnitus, or even paralysis of the nerves.

Pathologic Features

Microscopic Findings

Ceruminous adenomas are well circumscribed but unencapsulated ( Fig. 18.1 ). Surface involvement (not origin ) may be seen, whereas ulceration is absent. Tumors are divided into three subtypes based on specific histologic findings: ceruminous adenoma, ceruminous pleomorphic adenoma (chondroid syringoma), and ceruminous syringocystadenoma papilliferum. There is frequently a background of dense, sclerotic fibrosis that may simulate invasion. The tumors are moderately cellular, arranged in a mixture of glandular and cystic patterns each composed of a dual cell population ( Fig. 18.2 ). The inner luminal secretory cells have apocrine decapitation secretions or blebs and abundant granular, eosinophilic cytoplasm. Specifically, there are yellow-brown, ceroid, lipofuscin-like (cerumen, wax; acid-fast fluorescent) pigment granules within the cytoplasm of these luminal cells ( Fig. 18.3 ). These cells are surrounded by basal, myoepithelial cells lined up along the basement membrane ( Fig. 18.2 ). There is usually very limited pleomorphism, occasional nucleoli, rare mitoses, and a lack of necrosis.

A ceruminous pleomorphic adenoma is identical to a salivary gland pleomorphic adenoma, thus showing chondromyxoid matrix material (not native cartilage) juxtaposed to, and blended with, epithelium, with the added feature of ceruminous differentiation among the epithelial and “duct-like” cells ( Fig. 18.4 ). It is important to separate a primary EAC tumor from a parotid salivary gland tumor with local extension into the EAC. The ceruminous papillary cystadenoma papilliferum has papillary projections lined by cuboidal to columnar cells, a dense plasmacytic infiltrate, and cells with ceruminous differentiation ( Fig. 18.4 ).

Ancillary Studies

Immunohistochemistry is not necessary for the diagnosis, but stains can be used to highlight the biphasic nature of the tumor cells. Both cell types stain for epithelial membrane antigen (EMA) and pancytokeratin; the luminal cells uniquely stain for CK7 and preferentially stain for CD117, whereas the basal-luminal cells will stain with CK5/6, p63, and S100 protein ( Fig. 18.5 ). The cells lack a reaction with neuroendocrine markers and CK20.

Differential Diagnosis

This tumor type is unique to the EAC, with infrequent confusion with other tumors. Ceruminous adenocarcinoma has an infiltrative and destructive growth pattern, greater cellularity, cribriform growth, and pronounced nuclear pleomorphism with prominent nucleoli. Mitoses and necrosis may be seen. Ceroid pigmentation, seen in the luminal cells of benign adenoma, is notably absent. A middle ear adenoma may expand from the middle ear into the medial aspect of the EAC. This tumor also has a biphasic appearance, but the cells are plasmacytoid to cuboidal, have salt and pepper nuclear chromatin distribution, lack decapitation secretions, and have no ceroid granules in the cytoplasm. Furthermore, they are positive for neuroendocrine and peptide markers. A paraganglioma shows a classic zellballen (nested) architecture, cells with basophilic, slightly granular cytoplasm, and isolated pleomorphism. The paraganglia cells are immunoreactive with chromogranin, synaptophysin, and/or CD56, consistent with their neuroendocrine origin, whereas the sustentacular (supporting) cells will stain with S100 protein.

Prognosis and Therapy

Complete excision will be curative, although difficult to achieve due to the complex anatomy of the EAC. Therefore incomplete excision is not uncommon and is associated with an increased risk of recurrence.

Clinical Features

LCH is rare (∼5/1,000,000 population), more common in males, with a peak incidence in the 20s and 30s. Nearly 60% to 80% of cases develop in the head and neck, with ∼25% part of multisystem disease. The bone, particularly the skull, is most frequently affected, whereas only ∼4% of patients have ear/temporal bone involvement. Lesions of the middle ear and temporal bone may present with otorrhea, hearing loss, expansion of the temporal bone with a mass effect, pain, vertigo, otitis media, or skin ulceration. Bilateral temporal bone involvement is frequent.

Radiographic Features

LCH may demonstrate single or multiple lesions, usually readily detected by imaging studies as sharply circumscribed lytic lesions. Lesions of the skull characteristically have a “beveled” margin. If multiple lesions are present, the appearance may vary; some may have a poorly defined sclerotic border, which may reflect regression of the LCH and replacement by reactive bone. LCH tends to involve cortical bone, whereas rhabdomyosarcoma tends not to involve bone.

Pathologic Features

Microscopic Findings

The characteristic feature of LCH is the Langerhans cell, with its irregular, convoluted nucleus. The nuclei are somewhat bean shaped, with grooves and indentations that give them a cerebriform appearance ( Figs. 18.6 and 18.7 ). The chromatin pattern is fine and dispersed, with slight condensation along the nuclear membrane. Nucleoli are not prominent. Mitotic activity is variable but rarely exceeds 5/10 high-power fields. The cytoplasm is scant to moderate in volume and may be pale or eosinophilic and may contain hemosiderin or lipid droplets. In addition to the Langerhans cells, the lesions contain an admixture of usual histiocytes, eosinophils, plasma cells, and neutrophils. The number of eosinophils is variable; they may be scattered individually throughout the lesion or may form large sheets with central necrotic patches. Charcot-Leyden crystals are sometimes seen if eosinophils are numerous. Bone, if present, is usually seen as a reactive rim at the margin of the lesion. Regressing lesions are more fibrotic and may be more difficult to identify as LCH due to the paucity of the diagnostic cells.

Ancillary Studies

Immunohistochemistry

The Langerhans cells are identified by their positive immunoreactivity for S100 protein, CD1a ( Figs. 18.8 and 18.9 ), and CD207 (Langerin). Reactivity for CD1a, a relatively specific finding, is helpful in excluding the many other entities that are S100 protein positive, such as melanocytic lesions, Rosai-Dorfman disease, and xanthogranulomas. CD68 is also positive in the lesional cells ( Fig. 18.9 ). Langerin, a transmembrane protein which mediates the formation of Birbeck granules, is also sensitive and relatively specific for LCH.

Differential Diagnosis

Differential diagnostic considerations based on clinical presentation include infectious granulomatous processes , osteomyelitis , Rosai-Dorfman disease , and Hodgkin lymphoma . However, the suggestive radiographic appearance of punched-out lytic lesions of the craniofacial skeleton and identification of the Langerhans cell component by immunohistochemistry readily excludes these other lesions from further consideration.

Prognosis and Therapy

As noted previously, some lesions spontaneously regress or “heal.” Most isolated lesions of the skull are amenable to curettage or intralesional steroid injection. Such lesions have a very good prognosis. Low-dose radiation therapy is also useful, particularly in lesions not readily accessible surgically, whereas chemotherapy is also frequently used for multisystem disease. Extensive disease in younger patients portends a less favorable prognosis, particularly in the setting of visceral involvement. Long-term organ damage (hearing loss) may develop. Long-term follow-up is required due to high relapse, especially in multisystem disease.

Clinical Features

Patients usually present in the 5th to 6th decades of life but tend to be younger (< 21 years) when NF2 associated. Progressive, unilateral sensorineural (not conductive ) hearing loss and tinnitus (steam kettle–type hissing) occur in > 90% of patients, occasionally accompanied by headache, vertigo, altered balance and gait, facial pain, facial weakness, and changes in taste (the latter three symptoms due to brainstem compression by the tumor). Although the etiology is unknown, extended (∼20 years) occupational exposure to extremely loud noise, may be a risk factor in tumor development.

Radiographic Features

The best radiographic diagnostic clue is a CPA mass, with a funnel-shaped widening of the IAC or small indentation of bone. Magnetic resonance imaging (MRI) shows a hyperintense mass on T2-weighted images (with gadolinium contrast) with intense enhancement into the porus acusticus. Tumors are radiographically staged based on size, extent, and exact tumor location.