Spindle cell lipoma.

Spindle cell lipomas are a group of benign lipogenic soft tissue tumors. Typically they occur in posterior back and shoulder of elderly male patients. Differential diagnosis of this tumor became more important because the number of reports about some other tumors of similar morphology such as mammary type myofibroblastoma and solitary fibrous tumor, are increasing. All these tumors compose of bland spindle cells, mature adipocytes and collagen bundles. In this retrospective study we evaluated clinicopathological and immunohistochemical features of 18 cases of spindle cell lipomas. 15 cases of classical spindle cell lipomas and 3 pleomorphic lipoma variant were all histologically characteristic. Immuohistochemically they were all CD34 positive. Ten cases, whose paraffin blocks available, were desmin negative. We think that spindle cell lipomas are desmin negative tumors and this feature helps us to differentiate them especially from mammary type myofibroblastomas of extramammarian soft tissue.