title: Malignant mesenchymoma of the lower leg.
abstract: A 24 year old man had a two year history of a painless mass on his right popliteal region. Magnetic resonance imaging demonstrated a 6 x 8 cm tumour mass in the lateral gastrocnemius. Histological examination of the tumour resected by radical surgery revealed that it consisted of myoblastic sarcoma and chondrosarcoma. Immunohistochemical studies were positive for Ki-67 and p53 throughout the area and for S-100 protein in the chondrosarcomatous area; in addition, they showed partial positivity for muscle common actin (HHF-35), smooth muscle actin, and myoglobin in the spindle cells. The percentages of Ki-67, p53, and p21/WAF1 positive cells in the spindle cell component were 34%, 65.7%, and < 0.1%, respectively. In addition, staining was negative for pancytokeratin, desmin, and glial fibrillary acidic protein. The SYT-SSX, TLS-CHOP, and EWS-FLI1 fusion genes were not detected using the reverse transcription polymerase chain reaction. Given the results, the definitive histological diagnosis is malignant mesenchymoma. This is the first report of malignant mesenchymoma of the lower leg with immunohistochemical and molecular studies.
authors.affiliation: Department of Orthopaedic Surgery, Osaka National Hospital, 2-1-14 Hoenzaka, Chuo-ku, Osaka 540-0006, Japan. kudawara@onh.go.jp
authors.forename: I
authors.initials: I
authors.lastname: Kudawara
authors.forename: N
authors.initials: N
authors.lastname: Araki
authors.forename: H
authors.initials: H
authors.lastname: Nakanishi
authors.forename: M
authors.initials: M
authors.lastname: Mano
authors.forename: S
authors.initials: S
authors.lastname: Ishiguro
mesh_terms: D000328:Adult; D014408:Biomarkers, Tumor / Q000032:analysis; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins / Q000032:analysis; D006801:Humans; D019394:Ki-67 Antigen / Q000032:analysis; D007866:Leg; D008279:Magnetic Resonance Imaging; D008297:Male; D008637:Mesenchymoma / Q000737:chemistry / Q000473:pathology* / Q000601:surgery; D019042:Muscle Neoplasms / Q000737:chemistry / Q000473:pathology* / Q000601:surgery; D009418:S100 Proteins / Q000032:analysis; D016159:Tumor Suppressor Protein p53 / Q000032:analysis
chemical_list: D014408:Biomarkers, Tumor; C493956:CDKN1A protein, human; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins; D019394:Ki-67 Antigen; D009418:S100 Proteins; D016159:Tumor Suppressor Protein p53