Rare synchronous parotid tumors of different histologic types.

A review of the approximately 2000 parotid salivary gland tumors studied at the Columbia-Presbyterian Medical Center in New York from 1918 to 1978 showed that separate, synchronous neoplasms of different histologic types were found in the parotid gland in only 7 patients. In 6 of these patients, there was a clinically solitary mass; in the other patient, two separate nodules were palpated. In each case, subtotal or total parotidectomy was performed. On examination of the resected tissue, two separate nodules were identified grossly in three patients; in one, a benign mixed tumor and a mucoepidermoid carcinoma; in the second, a benign mixed tumor and a Warthin's tumor; and in the third, a mucoepidermoid carcinoma and a Warthin's tumor. In the remaining 4 patients, only one grossly evident tumor was found, including benign mixed tumor in 3 patients and a poorly differentiated adenocarcinoma in 1 patient. In each of these cases, the second tumor, discovered only microscopically, was a Warthin's tumor. Thus, in 6 of the 7 patients, the second neoplasm was a Warthin's tumor.