title: Low-grade fibrosarcoma of the proximal humerus.
abstract: We present the clinical, radiographical and pathological features of low-grade fibrosarcoma of the left proximal humerus in a 23-year-old man in whom it was necessary to distinguish the tumor from desmoplastic fibroma, malignant fibrous histiocytoma and intramedullary well-differentiated osteosarcoma. The patient presented with a 10-day history of pain in his left upper arm sustained when trying to break his fall with his left hand when slipping in the street. Plain radiography revealed an expanding multilobular osteolytic lesion from the proximal metaphysis to the diaphysis of his left humerus, accompanied by a pathological fracture at the distal portion of the lesion. Open biopsy of the lesion was performed twice; however, a conclusive diagnosis could not be obtained. The patient underwent wide excision and prosthetic replacement of the left proximal humerus. Histologically, the resected tumor was composed of both cellular areas and hypocellular areas. Cellular areas revealed a proliferation of bundles of uniform fibroblastic spindle-shaped cells with minimal cellular atypia, mixed with abundant intercellular collagenization. Mitotic figures were occasionally seen. Hypocellular areas showed myxoid features with loose bundles of collagen fibers. The patient demonstrates no evidence of disease 42 months after surgery. It is important to detect the scant atypical cells for the differential diagnosis of low-grade fibrosarcoma and desmoplastic fibroma of bone.
authors.affiliation: Department of Anatomic Pathology, Kyushu University, Graduate School of Medical Sciences, Fukuoka, Japan.
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Saito
authors.forename: Yoshinao
authors.initials: Y
authors.lastname: Oda
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Tanaka
authors.forename: Shuichi
authors.initials: S
authors.lastname: Matsuda
authors.forename: Akio
authors.initials: A
authors.lastname: Sakamoto
authors.forename: Hidetaka
authors.initials: H
authors.lastname: Yamamoto
authors.forename: Yukihide
authors.initials: Y
authors.lastname: Iwamoto
authors.forename: Masazumi
authors.initials: M
authors.lastname: Tsuneyoshi
mesh_terms: D000328:Adult; D001859:Bone Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology* / Q000601:surgery; D003937:Diagnosis, Differential; D018220:Fibroma, Desmoplastic / Q000175:diagnosis; D005354:Fibrosarcoma / Q000000981:diagnostic imaging / Q000473:pathology* / Q000601:surgery; D018219:Histiocytoma, Benign Fibrous / Q000175:diagnosis; D006801:Humans; D006811:Humerus / Q000000981:diagnostic imaging / Q000473:pathology* / Q000601:surgery; D008297:Male; D012516:Osteosarcoma / Q000175:diagnosis; D011859:Radiography; D016896:Treatment Outcome