Small cell carcinomas of the parotid gland. A clinicopathologic study of three cases.

Clinical, histological and ultrastructural features of three small cell carcinomas arising in the parotid gland are presented. The light microscopic appearance of two of the neoplasms suggested neuroendocrine cell derivation, confirmed by electron microscopy in both instances. The fine structure of the third neoplasm suggested intercalated duct cell differentiation. The possibility that both types of neoplasm may arise from the same primitive precursor cell is considered. The findings from this study confirm the occurrence of two different types of small cell carcinoma of salivary gland origin. A distinction between duct cell and neuroendocrine subtypes may be impossible by conventional light microscopic evaluation.