MIDDLE-EAR ADENOMA (MEA) - A REPORT OF 2 CASES, ONE WITH PREDOMINANT PLASMACYTOID FEATURES

Middle-ear adenomas (MEAs) are rare neoplasms which can display severa l histological patterns and represent a diagnostic challenge, We prese nt two cases of MEA which share some histopathological features such a s medium to small cells forming solid infiltrating tumour nests as wel l as scattered glandular structures with Alcian blue and PAS positive material within, The second case also displayed a distinct and predomi nant 'plasmacytoid' appearance which, in a small biopsy, might have be en misleading, Both cases expressed an admixture of epithelial and neu roendocrine immuno-histochemical markers, whereas ultrastructural stud y demonstrated electron dense granules, Taken together, these observat ions support a mixed epithelial and neuroendocrine nature for these ne oplasms, the differential diagnosis of which includes paragangliomas a nd other tumours or tumour-like lesions involving less frequently the middle ear, such as meningiomas, plasmacytomas and inflammatory polyps , The existence of MEAs with plasmacytoid features should be remembere d to avoid confusion with plasmacytomas, plasmacytoid myoepithelioma a nd plasma cell inflammatory infiltrates.