We report on a case of primary leiomyosarcoma of the bone in a 77-yr-old ma
n. The patient presented with a painful, enlarging mass in the left shoulde
r of 6 mo duration. Radiography and computed tomography (CT) revealed a lar
ge destructive intramedullary lesion of the proximal humerus, with massive
extension into the surrounding soft tissues. CT-guided fine-needle aspirati
on biopsies (FNAB) of both the bony and soft-tissue lesions were performed.
Cytological examination showed a neoplastic process composed of spindle ce
lls mixed with pleomorphic cells. The smooth muscle origin of the neoplasti
c cells was confirmed by immunocytochemical analysis. We describe the cytol
ogical features of this rare primary tumor of bone, and consider the differ
ential diagnosis of spindle-cell neoplasms. (C) 2001 Wiley-Liss, Inc.