FISH analysis of selected soft tissue tumors: Diagnostic experience in a tertiary center

• DOI: 10.1111/ajco.12980
• Publication Date: 2018-05-28T08:56:24Z
• Authors: Ana Cristina Vargas; Christina Selinger; Laveniya Satgunas...; Wendy A. Cooper; Ruta Gupta; Paul Stalley; Wendy Brown; Judy Soper; Julie Schatz; Richard Boyle; David M. Thomas; Martin H.N. Tatte...; Vivek Bhadri; Fiona Maclean; Sally Fiona Bonar; Richard A. Scolyer; Rooshdiya Z. Karim; Stanley W. McCarthy; Annabelle Mahar; Sandra A. O'Toole
• Keywords: Adult; Male; bones; DNA Copy Number Variations; diagnosis; Soft Tissue Neoplasms; Tertiary Care Centers; Young Adult; 03 medical and health sciences; 0302 clinical medicine; XXXXXX - Unknown; cancer; Humans; molecules; fluorescence in situ hybridization; In Situ Hybridization, Fluorescence; Aged; Aged, 80 and over; Gene Rearrangement; Australia; Middle Aged; Neoplasm Proteins; Female; soft tissues

AbstractAimFluorescence in situ hybridization (FISH) is an important ancillary tool for the classification of bone/soft tissue (BST) tumors. The aim of this study was to evaluate the contribution of FISH to the final classification of common BST entities in the molecular pathology department of the Royal Prince Alfred Hospital (RPAH), which is one of the most important referral centers for the management of sarcomas in Australia.MethodsAll routine diagnostic FISH tests performed on BST formalin‐fixed paraffin embedded (FFPE) tissue specimens at the RPAH in a 5‐year period (February, 2010–November, 2015) were reviewed. FISH analyses presented in this study include commercial break‐apart probes (SS18, FUS, DDIT3, FUS, USP6, PDGFB, TFE3 and ALK) and a single enumeration (MDM2) probe.ResultsThere were 434 interpretable FISH assays on BST samples including MDM2 (n=180), SS18 (n=97), FUS (n=64), DDIT3 (n=37), USP6 (n=30), PDGFB (n=13), TFE3 (n=8) and ALK (n=5). Discrepancies between the histopathological diagnosis and the FISH results were seen in 12% of the cases. In this subset of discordant cases, FISH contributed to the re‐classification of 7% of cases originally diagnosed as synovial sarcoma (SS18) and 6% of adipocytic neoplasms (MDM2) based on the presence or absence of the expected gene alteration.ConclusionOur study confirms that paraffin FISH is a sensitive and specific ancillary tool in the diagnosis of BST neoplasms when used in the appropriate clinicopathological context. These findings highlight the need for further ancillary molecular tools in the diagnosis and characterization of challenging cases.