Testicular seminoma metastasizing to the parotid gland: report of a case.

Abstract

Among salivary glands, the parotid gland is the most common site for secondary neoplastic involvement, and carcinomas and melanomas are the two most common secondary tumors. We present a case of testicular seminoma metastasizing to the parotid gland. The patient, who had a remote history of testicular seminoma, was initially seen with a parotid mass. A primary parotid lesion was anticipated, and excisional biopsy was performed. The diagnosis of testicular seminoma metastasizing to the parotid gland was established on the basis of histologic findings and was confirmed by immunohistochemical analysis. Metastatic and primary seminomas have the same morphologic features and cellular composition, and granulomatous reaction is often present in both neoplasms. Extragonadal seminoma often occurs in the midline (presacral, retroperitoneal, anterior mediastinal, and pineal regions); when present in any other locations, the tumor should be considered to be metastatic. Placenta alkaline phosphatase is a useful immunohistochemical stain to confirm the diagnosis, and cytokeratin immunohistonegativity rules out carcinomas or epithelioid sarcomas. To our knowledge, this is the first published case of metastatic testicular seminoma to the parotid gland. Cytomorphologic features of seminoma and the presence of granulomatous giant cells are important diagnostic clues. Two other neoplasms with granulomatous reactions, nasopharyngeal carcinoma and epithelioid sarcoma, should be considered in the differential diagnosis.