Leiomyosarcoma of the Broad Ligament With Osteoclast-like Giant Cells and Rhabdoid Cells:

Primary leiomyosarcoma of the breast with prominent osteoclastic giant cells: A case expressing receptor activator of NF-κB ligand (RANKL)

Primary sarcomas of the breast are rare, accounting for less than 1% of all breast neoplasms. Leiomyosarcoma is one of the least common breast sarcoma subtypes, and less than 50 cases of primary breast leiomyosarcomas have been reported in the English literature. In other types of leiomyosarcoma, osteoclastic giant cells (OGCs) are occasionally admixed with tumor cells; however, this is rarely seen in primary breast leiomyosarcoma. We herein present the case of a 50-year-old woman with OGC-containing primary breast leiomyosarcoma whose tumor cells showed positive immunostaining for receptor activator of NF-κB ligand (RANKL). The presence of OGCs in tumors generally indicates tumor aggressiveness. This is true for leiomyosarcoma of the soft tissue and might be true for leiomyosarcoma of primary breast origin. Regarding RANKL expression, in giant cell tumor of bone (GCTB) in which OGCs expressing RANK were abundant, tumor cells are known for expressing RANKL. Therapy targeting RANKL decreases the number of tumor cells of GCTB. Our findings are clinically relevant as they indicate that RANKL expression should be investigated in various tumors containing OGCs. This might lead to the development of future molecule-targeted therapy.