Table 3 Differential diagnoses of OMEC

Oncocytic mucoepidermoid carcinoma

+

+

Solid cystic tumor predominantly showing proliferation of oncocytes with cystic spaces lined by mucous cells, squamoid cells, and intermediate cells

Diffuse p63, p40, CK5/6, mucin stain positive in mucous cells; frequently positive for MAML2 rearrangement

Oncocytoma

occasional

–

Encapsulated neoplasm growing in an organoid pattern separated by thin fibrous septae. Squamoid and mucous cells are absent.

Peripheral/basal p63, p40, CK5/6 staining; negative for mucin stain

Oncocytic carcinoma

–

Single, or multinodular unencapsulated, neoplasm. Trabeculae, sheets, and nests of pleomorphic oncocytes infiltrating the salivary gland parenchyma. Squamoid and mucous cells are absent.

Positive for p63, p40 and CK5/6 in peripheral/basal distribution; negative for mucin stain

Metaplastic Warthin’s tumor

+

+

Papillary cystic neoplasm demonstrating a bilayered epithelium lined by oncocytic and basal cells in a lymphoid stroma. Squamous and mucin producing cells may be identified.

Metaplastic squamous epithelium is positive for p40, p63 and CK5/6 staining. Mucicarmine is positive in mucous cells.

Secretory carcinoma

+/−

–

Lobulated growth of neoplastic cells showing eosinophilic to vacuolated cytoplasm with vesicular bland nuclei. It exhibits cystic, solid, tubular, follicular and papillary architectural patterns

Pale eosinophilic periodic acid-Schiff (PAS) positive and diastase resistant intraluminal secretions are present.

Positive for GATA 3, mammoglobin, and S100 immunostains; ETV6 translocation (usually with partner gene NTRK3); myoepithelial cell stains (p63, S100, actin) are negative

Oncocytic pleomorphic adenoma

–

+

Encapsulated triphasic neoplasm with epithelial, myoepithelial and chondromyxoid stromal component. Squamous and mucinous metaplasia may be seen.

Peripheral/basal p63, p40 staining; S100 is positive in myoepithelial cells, c-kit positive in ductal component

Plasmacytoid myoepithelioma

–

–

Large plasmacytoid cells in cords, clusters and sheets in a myxoid stroma.

Positive p63, actin, calponin and S100 staining

Salivary duct carcinoma

+

–

Invasive oncocytic tumor cells arranged in cords, cribriform glands and nests showing high grade nuclear features in a desmoplastic stroma.

Positive for CK7, GCDFP and androgen receptor; p63, p40 and CK5/6 are mostly negative