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Detection of specific genetic abnormalities by fluorescence in situ hybridization in soft tissue tumors

Authors


Tadashi Hasegawa, MD, PhD, Department of Surgical Pathology, Sapporo Medical University School of Medicine, South 1, West 16, Chuo-ku, Sapporo 060-8543, Japan. Email: hasetada@sapmed.ac.jp

Abstract

For the detection of chromosome translocations/chimeric genes and specific genetic abnormalities in soft tissue tumors, we conducted fluorescence in situ hybridization (FISH) analysis on 280 cases of soft tissue and other tumors using formalin-fixed paraffin-embedded tissue sections. The detection rate of the FISH split-signal was 84% (129/154 cases) for the translocation-associated soft tissue tumors, such as Ewing's sarcoma/primitive neuroectodermal tumor, synovial sarcoma, alveolar rhabdomyosarcoma, myxoid liposarcoma, clear cell sarcoma and so forth. Positive split-signals from EWSR1, SS18 and FOXO1A probes were detected in 3% (2/64) of various histological types of carcinoma, lymphoma, melanoma, meningioma and soft tissue tumors. In FISH using the INI1/CEP22 probe, the INI1 deletion signal was detected in 100% (9/9) of epithelioid sarcoma. In well-differentiated and dedifferentiated liposarcomas, detection of MDM2 amplification signals in FISH using the MDM2/CEP12 probe were both as high as 85% (11/13) and 100% (13/13), respectively. In other adipocytic and non-adipocytic tumors requiring differentiation from these types, detection was only 13% (5/39), and CEP12 polysomy was frequently detected. As these results demonstrate the high sensitivity and specificity of FISH, we concluded FISH to be a useful pathological diagnostic adjunct for definite and differential diagnosis of soft tissue tumors.

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