title: Intraosseous leiomyosarcoma arising in the epiphysis of the distal femur.
abstract: Herein, we present a rare case of intraosseous leiomyosarcoma arising in the epiphysis of the distal femur and showing unusual radiographic features. A 44-year-old man presented with a pain in the left knee joint. Computed tomography revealed an intraosseous lesion with slightly increased attenuation and a thin marginal sclerotic rim in the femoral medial condyle. The signal of the lesion was hypointense on T1-weighted magnetic resonance (MR) images and hyperintense on fat-suppressed T2-weighted MR images. After gadolinium administration, the signal of the lesion was moderately and diffusely enhanced. The histological diagnosis of leiomyosarcoma was made based on a preoperative core biopsy specimen. Microscopic examination of the resected specimen revealed an ill-defined intraosseous tumor composed of proliferated atypical and mildly pleomorphic smooth muscle cells permeating among the bone trabeculae with only focal destruction of the bone trabeculae and low mitotic activity, indicating low grade leiomyosarcoma. The bone trabeculae at the periphery of the tumor were mildly thickened and anastomosed with a rim of an increased number of osteoblasts. Systemic examination showed no tumorous lesions in other anatomical sites. Leiomyosarcomas rarely present in the bone as a diffuse intertrabecular growth, even in low grade tumors.
authors.affiliation: Department of Pathology and Oncology, School of Medicine, University of Occupational and Environmental Health, Japan.
authors.forename: Atsuji
authors.initials: A
authors.lastname: Matsuyama
authors.forename: Akio
authors.initials: A
authors.lastname: Sakamomo
authors.forename: Takatoshi
authors.initials: T
authors.lastname: Aoki
authors.forename: Masanori
authors.initials: M
authors.lastname: Hisaoka
mesh_terms: D000328:Adult; D014408:Biomarkers, Tumor / Q000032:analysis; D001706:Biopsy; D049109:Cell Proliferation; D003287:Contrast Media; D004838:Epiphyses / Q000737:chemistry / Q000000981:diagnostic imaging / Q000473:pathology* / Q000601:surgery; D005266:Femoral Neoplasms / Q000737:chemistry / Q000000981:diagnostic imaging / Q000473:pathology* / Q000601:surgery; D006801:Humans; D007150:Immunohistochemistry; D007890:Leiomyosarcoma / Q000737:chemistry / Q000000981:diagnostic imaging / Q000473:pathology* / Q000601:surgery; D008279:Magnetic Resonance Imaging; D008297:Male; D060787:Neoplasm Grading; D009361:Neoplasm Invasiveness; D014057:Tomography, X-Ray Computed
chemical_list: D014408:Biomarkers, Tumor; D003287:Contrast Media
keywords: CT; Epiphysis; Intraosseous; Leiomyosarcoma; Permeative growth