8. Myometrial osteosarcoma

Abstract

Case summary The patient is a 56-year-old female with a history of menorrhagia and a fibroid uterus who underwent total abdominal hysterectomy and bilateral salpingoophorectomy. Macroscopi-cally a sharply circumscribed myometrial nodule occupied the uterine corpus, the cut surface of which showed extensive necrosis and haemorrhage with cystic change. No macroscopic myometrial invasion was identified. Histologically the nodule comprised malignant osteoid associated with fibroblastic foci and osteo-clast-like multinucleated giant cells (MNGC). No carcinomatous elements were identified. Following extensive sampling and review by specialist gynaecological pathologists, a final diagnosis of myometrial osteosarcoma was confirmed. Discussion Occurring predominantly in postmenopausal women, uterine osteosarccoma presents with symptoms analogous to carci-nosarcoma, although the prognosis is worse. Histologically, immu-nohistochemically and ultrastrucurally it is similar to its osseous counterpart. Thus diagnostic difficulties arise when trying to differentiate between primary osteosarcoma of the uterus and metastasis from a bone primary or carcinomasarcoma. However, establishing the absence of carcinomatous components by light microscopy, immunohistochemistry or ultrastructural studies makes carcinosar-coma less likely. Likewise radiological exclusion of a primary osseous lesion would rule out metastatic osteosarcoma. Conclusion Three key criterion need to be met prior to the diagnosis of primary uterine osteosarcoma. These include confirmation of the presence of malignant osteoid, the absence of malignant epithelial components, and exclusion of a primary osseous osteosarcoma. To that end, extensive specimen sampling and clinicopathological correlation, in particular radiological assessment, are essential.