Answer: Ceruminous adenoma

Histology: The tumor consists of a circumscribed proliferation of glands exhibiting cystic dilatation. At high power, it is evident that the glands have 2 cell types: an inner layer of eosinophilic cells with apocrine snouts and an outer layer of cleared cells. The tumor was not infiltrative, and no mitotic figures or necrosis were observed.

Discussion: When dealing with tumors of the ear, to form a differential diagnosis it is important to determine where in the ear the tumor is arising (i.e., inner, middle, or external). Middle ear adenomas obviously arise from the middle ear, while endolymphatic sac tumors arise from the inner ear and ceruminous adenomas arise in the external ear. While we are not told in this case where the tumor is located, at low power adnexal structures (including normal ceruminous glands) are evident consistent with external ear. Ceruminous adenomas are glandular neoplasms comprised of an inner layer exhibiting ceruminous differentiation an outer layer of myoepithelial cells. They are benign, though they may recur if incompletely excised

Reference(s):
– hompson LD, Nelson BL, Barnes EL. Ceruminous adenomas: a clinicopathologic study of 41 cases with review of the literature. Am J Surg Pathol. 28(3):308-18.

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