Abstract
Context—Mesenchymal neoplasms harbor characteristic translocations and amplification of gene regions amenable to evaluation by fluorescence in situ hybridization (FISH).
Objective—To determine the utility of FISH in the diagnosis of mesenchymal neoplasms.
Design—Two hundred thirty soft tissue cases analyzed by FISH were reviewed retrospectively.
Results—Morphologic patterns where FISH was used included high-grade round cell sarcomas (n = 67), nonmyogenic spindle cell sarcomas (n = 40), low-grade myxoid neoplasms (n = 34), adipocytic neoplasms (n = 20), and melanocytic neoplasms (n = 19). Fifty cases did not fit into the previously mentioned categories. SYT FISH (96% of monophasic synovial sarcomas were positive; 0% of malignant peripheral nerve sheath tumor were positive) and DDIT3 FISH (100% of myxoid/round cell liposarcomas; no other neoplasm positive) were very sensitive and specific. EWSR1 FISH was very sensitive and specific in the differential diagnosis of melanocytic neoplasms (88% of clear cell sarcomas were positive; all melanomas were negative). EWSR1 FISH was sensitive among high-grade round cell sarcomas (positive in 100% of desmoplastic small round cell tumors and 96% of Ewing sarcoma/primitive neuroectodermal tumors) but not specific because clear cell sarcoma, extraskeletal myxoid chondrosarcoma, and a subset of round cell liposarcomas also harbor rearrangements of EWSR1. FUS FISH was very sensitive in detecting low-grade fibromyxoid sarcomas (91% positive) but not specific because most myxoid/round cell liposarcomas also contain rearrangements of FUS. All atypical lipomatous tumors were positive for amplification of MDM2, whereas all lipomas were negative. FOXO1A FISH was positive in ∼70% of cases of alveolar rhabdomyosarcoma.
Conclusion—FISH is a useful adjunct in the diagnosis of mesenchymal neoplasms.
High-Throughput Molecular Profiling of High-Grade Astrocytomas: The Utility of Fluorescence In Situ Hybridization on Tissue Microarrays (TMA-FISH)
