Small cell carcinoma of the major salivary glands. An immunohistochemical study

Small cell carcinomas of the major salivary glands are rare tumors, accounting for less than 1% of malignant neoplasms at these sites. To date, approximately 41 such tumors have been described. They recently have been classified into two groups, based on the ultrastructural presence or absence of intracytoplasmic neuroendocrine (NE) granules, "small cell neuroendocrine carcinoma" and "small cell ductal carcinoma". This study concerns 11 primary small cell carcinomas that had been previously studied ultrastructurally; it was undertaken to determine whether these lesions possessed a neuroendocrine phenotype, using a battery of immunohistochemical stains. Antibodies to epithelial membrane antigen (EMA), cytokeratin (CK), Leu 7, vimentin (VIM), synaptophysin (SYN), chromogranin (CHR), and neuron-specific enolase (NSE) were employed, with the avidin-biotin-peroxidase complex technique and paraffin sections. All tumors in this study expressed at least one neuroendocrine marker. In eight tumors EMA was found; CK was present in all 11 cases, seven of which demonstrated focal paranuclear staining. Leu 7 was seen in eight tumors, VIM was expressed in two cases, SYN was found in three tumors, and CHR was detected in three neoplasms. Anti-neuron-specific enolase labeled eight tumors. From the preceding data one may conclude that all small cell salivary gland carcinomas have neuroendocrine characteristics, even though dense core granules cannot be demonstrated in some of them ultrastructurally.