Undifferentiated carcinomas of the major salivary glands.

Undifferentiated salivary carcinomas are defined as primary epithelial malignant neoplasms that are devoid of any phenotypic expression by light microscopy that would allow them to be otherwise classified. A clinicopathologic study of sixteen so-defined carcinomas of the major salivary glands is presented. The carcinomas are unquestionably high-grade malignant neoplasms. Ten of the sixteen patients were dead because of their disease within 4 1/2 years of histologic diagnosis. Cell size and ultrastructural features have little bearing on prognosis. The single most important clinicopathologic factor relating to patient outcome is size of the primary neoplasm. All patients with carcinomas larger than 4 cm died, and these carcinomas had nearly two times the incidence of perineural invasion, extrasalivary extension, and locoregional failure of control.