Primary leiomyosarcoma of bone: a clinicopathologic and immunohistochemical study of 142 cases

Leiomyosarcoma is a rare malignant mesenchymal tumor characterized by smooth muscle differentiation. It typically arises in both visceral and somatic soft tissues, while involvement of bone being exceptionally uncommon. Although primary leiomyosarcoma of bone has been a subject of ongoing debate, the advent of immunohistochemistry has reduced the misclassification of other sarcomas, such as fibrosarcoma and undifferentiated pleomorphic sarcoma, facilitating the accurate identification of true primary LMSB cases. To date, just over 200 well-documented LMSB cases have been published in English-language literature. Despite this, understanding of its clinical behaviour and factors influencing patient outcomes remains limited. In this study, we present the clinical, pathological, and immunohistochemical findings from 142 cases of primary bone leiomyosarcoma including extended follow-up data.