Subcutaneous leiomyosarcoma with lymphomatous elements: histogenetic implications of an unusual sarcoma.

A 49-year-old woman had an unusual sarcoma that recurred three times in four years. The tumor manifested initially as a subcutaneous abdominal wall nodule composed of lymphohistiocytic malignant lymphoma and spindle cell sarcoma with epithelioid and clear cell elements. The neoplasm recurred first as a spindle cell sarcoma in the lumbar area, second as a malignant lymphoma in the subcutaneous tissue of the right shoulder, and third as a spindle cell sarcoma with lymphohistiocytic areas in the abdominal wall. Ultrastructural studies of this last tumor nodule demonstrated the unequivocal smooth muscle features of the spindle cells. Histogenetic implications of this neoplasm are discussed. It is proposed that the tumor represents an unusual variant of malignant mesenchymoma of soft tissues.