Leiomyosarcoma with osteoclast‐like (LMS‐OGC) giant cells the breast: A report of a rare case

Leiomyosarcoma with osteoclast‐like giant cells (LMS‐OGC) has seldom been reported clinically. LMS‐OGC of the breast is extremely rare according to the literature. Here, we report a case of LMS‐OGC leiomyosarcoma with osteoclast‐like giant cells of the breast. A 51‐year‐old female patient presented with a breast mass which was treated surgically and the pathological examination of the tumor indicated LMS‐OGC. Microscopically, the tumor was composed of spindle cells arranged in bundles or spokes with giant tumor cells and mitosis. Eosinophilic cytoplasm and morphologically benign osteoclast‐like cells were mixed together. Immunohistochemistry examination revealed SMA and desmin were positive with a Ki‐67 proliferation index of 40%. However, CK (AE1/AE3), E‐cadherin, ER, PR, CD34, S‐100 and CD10 were negatively expressed in the tumor tissue. LMS‐OGC is a soft tissue malignant tumor which develops extremely rarely in the breast. It should be differentiated and diagnosed according to the history, histological characteristics and immunohistochemical staining.