Inflammatory leiomyosarcoma of the retroperitoneum.

We present a case of an inflammatory leiomyosarcoma, a variant of smooth muscle cell tumor that could be mistaken for inflammatory malignant fibrous histiocytoma. The inflammatory cell infiltrates obscured the basic architecture of the tumor, and immunohistochemistry was required to arrive at the proper diagnosis. Since inflammatory leiomyosarcomas are rare and possibly misdiagnosed neoplasms, there are not enough data to indicate whether they deserve to be separated from other malignant smooth muscle cell neoplasms. By reporting this case we hope that more pathologists will become aware of this tumor type and that more cases will be collected for future clinicopathologic studies.