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Logo of jclinpathJournal of Clinical PathologyCurrent TOCInstructions for authors
 
J Clin Pathol. Nov 2001; 54(11): 877–879.
PMCID: PMC1731318
Malignant mesenchymoma of the lower leg
I Kudawara, N Araki, H Nakanishi, M Mano, and S Ishiguro
Department of Orthopaedic Surgery, Osaka National Hospital, 2-1-14 Hoenzaka, Chuo-ku, Osaka 540-0006, Japan. kudawara/at/onh.go.jp
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 gastrocunemius. 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.
Key Words: malignant mesenchymoma • lower leg
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Figure 1 Axial magnetic resonance imaging scan showing the tumour in the lateral gastrocunemius, which had an inhomogeneous intensity on T2 weighted image.
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Figure 2 The spindle cell component of the tumour with occasional atypical mitoses. The tumour cells express myoglobin (ABC method). Original magnification, x50.
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Figure 3 The chondrosarcoma (grade 2) region with moderate cellular atypism. Note also the adjacent area of spindle cell sarcoma. Haematoxylin and eosin stain; original magnification, x50.
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Figure 4 Area of bone formation in the spindle cell component. Haematoxylin and eosin stain; original magnification, x25.
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