Sarcomatoid salivary duct carcinoma of the parotid gland

Salivary duct carcinoma (SDC) is a high-grade neoplasm known to histologica lly resemble high-grade ductal carcinoma in situ of the breast. We describe 3 cases of sarcomatoid salivary duct carcinoma, a heretofore unreported va riant of SDC. Each case was a composite of SDC and sarcomatoid carcinoma an d histologically similar to reported cases arising in the breast. The clini copathologic features, including immunohistochemistry, of 3 cases were inve stigated. In the 3 men, ages 56, 68, and 70 years, the resected parotid tum ors measured 1.5, 3.5, and 1.5 cm, respectively. Only the 3.5-cm tumor exte nded beyond the parotid gland into soft tissue. This patient died at 3 year s with pulmonary metastases, The other patients were free of disease at 6 a nd 12 months. Histologically, each case was a composite of usual-type SDC a nd sarcomatoid carcinoma. SDC showed typical cribriform architecture, where as anaplastic, spindled cells constituted the sarcomatoid areas. Immunohist ochemically, epithelial elements stained as follows: cytokeratin (AE1/AE3 & CAM 5.2) positive in 3 of 3 cases, EMA positive in 3 of 3 cases, vimentin negative in 3 of 3 cases, desmin negative in 3 of 3 cases, c-erbB-2 positiv e in I of 2 cases. Sarcomatoid elements stained as follows: AE1/AE3 negativ e in 3 of 3 cases, CAM 5.2 rare positive cell in 1 of 3 cases, EMA focally positive in 3 of 3 cases, vimentin positive in 3 of 3 cases, desmin negativ e in 3 of 3 crises, c-erbB-2 negative in 2 of 2 cases. Electron microscopy, performed in one case, showed scattered junctional complexes congruent wit h epithelial differentiation. Immunohistochemical results, EMA and CAM 5.2 positivity, and ultrastructural findings supported our belief that these un ique biphasic tumors represented SDC with sarcomatoid carcinoma. We conclud e an element of sarcomatoid carcinoma rarely may arise in association with SDC, and it is erroneous to diagnose such tumors as "carcinosarcoma." Copyr ight (C) 2000 by W.B. Saunders Company.