Bizarre leiomyoblastoma (epithelioid leiomyosarcoma) of the uterus--a case with a malignant clinical course.

A case of a bizarre leiomyoblastoma (epithelioid leiomyosarcoma) which developed in the uterus of a 64-year-old woman and showed a malignant clinical course was reported. Histologically, the tumor in the present case had a number of bizarre giant cells, while the portion showing an epithelioid pattern was minor. Since the existence of an intimate inter-relationship between tumor cells and the smooth muscles of the blood vessel wall was a characteristic finding in the present case, a possible role of vascular smooth muscles as a tumorigenic matrix was suggested. Because of the closure of the internal os of the uterus by the tumor, the uterus had a cystomorphous appearance, and contained about 800ml of intrauterine fluid. The highest number of mitosis observed was 7 per 10 HPF. In view of abundant existence of intranuclear cytoplasmic inclusions, the malignancy of the present case was strongly suspected from a histological diagnostic point of view. The patient died 5 months after surgery because of metastases to the lumbar vertebra and to the lung.