title: Osteoclast-like cells in soft tissue leiomyosarcomas.
abstract: Giant cell-rich leiomyosarcoma of soft tissues is an unusual variant of malignant smooth muscle tumor characterized by the presence of numerous multinucleated giant cells (MNGCs). The nature of MNGCs and the cellular mechanisms underlying their accumulation in this tumor are poorly understood. Analysis of the expression of osteoclast, macrophage, and smooth muscle markers in two cases of giant cell-rich leiomyosarcoma revealed that the MNGCs in giant cell-rich leiomyosarcoma were negative for smooth muscle markers and that these cells expressed an osteoclast-like phenotype, being positive for CD45, CD68, tartrate-resistant acid phosphatase, and CD51 but negative for CD14 and HLA-DR. Scattered tumor-associated macrophages (TAMs) also expressed this phenotype. Leiomyosarcoma tumor cells strongly reacted for CD51 but were negative for CD14, CD45, and CD68. An analysis of 25 conventional (nongiant cell-containing) leiomyosarcomas found isolated CD68(+) MNGCs in three cases (12%), all of which were grade II/III leiomyosarcomas containing a prominent TAM infiltrate. Leiomyosarcoma-derived TAMs in the presence of receptor activator for nuclear factor kappa B ligand (RANKL) and macrophage colony-stimulating factor were capable of differentiating into osteoclast-like cells capable of resorbing bone. Reverse transcription polymerase chain reaction studies showed that RANKL, osteoprotegerin, and TNF-related apoptosis-inducing ligand were expressed by leiomyosarcoma cells. Our findings indicate that the giant cells found in leiomyosarcomas are osteoclast-like and that they are formed from TAMs by a RANKL-dependent mechanism.
authors.affiliation: Department of Pathology, Nuffield Dept of Orthopaedics, Rheumatology and Musculoskeletal Science, University of Oxford, Nuffield Orthopaedic Centre, Headington, Oxford, OX3 7LD, UK.
authors.forename: C L M H
authors.initials: CL
authors.lastname: Gibbons
authors.forename: S G
authors.initials: SG
authors.lastname: Sun
authors.forename: M
authors.initials: M
authors.lastname: Vlychou
authors.forename: K
authors.initials: K
authors.lastname: Kliskey
authors.forename: Y S
authors.initials: YS
authors.lastname: Lau
authors.forename: A
authors.initials: A
authors.lastname: Sabokbar
authors.forename: N A
authors.initials: NA
authors.lastname: Athanasou
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D015726:Giant Cells / Q000473:pathology*; D006801:Humans; D007890:Leiomyosarcoma / Q000473:pathology* / Q000503:physiopathology; D008264:Macrophages / Q000473:pathology; D008297:Male; D010010:Osteoclasts / Q000378:metabolism / Q000473:pathology*; D053244:Osteoprotegerin / Q000096:biosynthesis; D053245:RANK Ligand / Q000096:biosynthesis; D012983:Soft Tissue Neoplasms / Q000473:pathology* / Q000503:physiopathology; D053221:TNF-Related Apoptosis-Inducing Ligand / Q000096:biosynthesis
chemical_list: D053244:Osteoprotegerin; D053245:RANK Ligand; D053221:TNF-Related Apoptosis-Inducing Ligand; C506030:TNFRSF11B protein, human; C505653:TNFSF10 protein, human; C505688:TNFSF11 protein, human