Case report of undifferentiated endometrial sarcoma in association with osteoclast-like giant cells.

We describe the clinical, gross and microscopic features of undifferentiated uterine stromal sarcoma associated with osteoclast-like giant cells. A case of low-grade endometrial stromal sarcoma is already described in association with osteoclast-like giant cells; however, the current case differs in that the tumor was a high grade and did not show any evidence of smooth muscle or epithelioid differentiation and was shown to be strongly positive for CD10 and focally for WT-1 and Inhibin supporting an endometrial stromal origin. The associated osteoclast-like giant cells were abundant, evenly distributed within the tumor and showed strong positivity for CD68. Interestingly, rare (less than 2%) giant cells also showed weak cytoplasmic positivity for b-hCG. The tumor infiltrated deep into the myometrium and had marked lymphovascular invasion. Although the regional lymph nodes and peritoneal washings were negative, the lesion showed a highly aggressive clinical course. Despite treatment, the tumor disseminated within the abdominal cavity and lungs and ultimately led to the patient's demise within 9 months of the diagnosis.