Intraductal carcinoma of the parotid gland, mixed intercalated duct and oncocytic subtype with mucinous and serous acinar differentiation: cytologic and histologic features of a novel morphology.

Intraductal carcinoma (IDC) of the salivary gland is rare. Histologic subtypes include intercalated duct, oncocytic, apocrine, and hybrid/mixed. Molecular correlates have been described, with intercalated duct IDC typically harboring NCOA4::RET, while TRIM33::RET, or BRAF pathogenic variants predominating in oncocytic IDC.