Salivary duct carcinoma with squamous differentiation: histomorphological and immunophenotypical analysis of six cases.

Squamous differentiation, histologically and immunophenotypically, can be extensive in SDC. AR expression may be lost in the squamous component and metastases may demonstrate only squamous differentiation. These findings cast further doubt on the existence of primary salivary SCC. SDC should be considered whenever encountering a carcinoma with squamous differentiation in major salivary glands or within cervical lymph nodes in the setting of a salivary mass.