Sarcomatoid variant of salivary duct carcinoma: clinicopathologic and immunohistochemical study of eight cases with review of the literature.

Salivary duct carcinoma (SDC) is an uncommon, high-grade tumor. We present 8 cases of sarcomatoid SDC, which has been defined recently as a rare variant of SDC. The 8 patients (5 men, 3 women) had a mean age of 63.6 years. Histologically, all tumors were characterized by a biphasic neoplasm composed of both SDC and sarcomatoid elements. In 3 cases, sarcomatoid components showed osteosarcomatous heterologous differentiation. A residual pleomorphic adenoma was detected in 5 tumors. The sarcomatoid component showed focal immunoreactivity for cytokeratin in 4 cases and epithelial membrane antigen in all 8 cases. Diffuse p53 immunostaining was detected in 3 cases, and it was coexpressed in both components. Our observations support the histogenetic theory of a common origin of the carcinomatous and sarcomatoid populations. Of the 13 patients, including our 8, reported to have sarcomatoid SDC arising in a major salivary gland and for whom long-term follow-up data were available, 7 have died of disease (mean survival, 15.6 months). These results indicate that sarcomatoid SDC is a highly aggressive tumor, similar to conventional SDC.