Uterine leiomyosarcoma with osteoclast-like giant cells: histopathological and cytological observations.

A 56 year old woman presented with abnormal uterine bleeding. Except for a myomatous uterus, no other abnormalities were noted on physical examination and in radiographic and serologic studies. The hysterectomy specimen revealed an 8 cm uterine fundic tumor composed of two histologically different patterns that merged with one another; one was a well differentiated leiomyosarcoma and the other a mixture of osteoclast-like giant cells (OGC) and plump spindle cells whose cell borders blended, resembling the histology of giant cell tumor of bone. Immunohistochemical studies showed positive staining for muscle actin, alpha-smooth muscle actin, and KP-1 (CD68) in both the spindle cells and OGC. The latter also stained for alpha-1-antitrypsin and alpha-1-antichymotrypsin. These findings suggested that OGC may be formed by the fusion of spindle cells of leiomyosarcoma and also express histiocytic markers.