Desmoplastic small round cell tumors: cytologic, histologic, and immunohistochemical features.

Desmoplastic small round cell tumor (DSRCT) is a recently recognized clinicopathologic entity that has a predilection for adolescent males and usually affects the abdominal cavity. Due to its uncommon nature, many pathologists lack experience with this tumor. The literature regarding DSRCT is reviewed with special attention to its histologic and cytologic diagnosis. Morphologic features of DSRCT and its immunohistochemical and cytogenetic profile are summarized and differential diagnosis with other small round cell tumors is discussed. As observed by both histologic and cytologic examinations, small round blue cells and fibrosclerotic stroma are the striking morphologic features of DSRCT. The typical immunohistochemical profile is characterized by coexpression of epithelial, mesenchymal, myogenic, and neural markers. Cytogenetically, this tumor harbors a specific karyotypic abnormality, namely t(11;22)(p13;q12). These features distinguish DSRCT from other members of the family of small round cell tumors.