[94] Utilization of FISH in the Diagnosis of 235 Mesenchymal Neoplasms: An Institutional Experience

MR Tanas, BP Rubin, R Tubbs, SD Billings, JR Goldblum. Cleveland Clinic, Cleveland, OH

Background: FISH can detect the translocation and amplication of genes in mesenchymal neoplasms. We report our experience with FISH in 235 mesenchymal neoplasms.
Design: We reviewed 235 consecutive soft tissue consults over a 30 month period where FISH was performed. Probes to EWSR1, FUS, DDIT3, FOXO1A and the MDM2 gene region were used. Major morphological patterns included high grade round cell sarcomas (HGRCS; n=67), high grade spindle cell sarcomas (SSS; n=47), and low grade myxoid (LGMN; n=34), melanocytic (MN; n=19), and adipocytic neoplasms (AN; n=20). Forty-eight cases did not fit into the above patterns.
Results: FISH was utilized in 9% of our soft tissue consults. The most useful probes for the aforementiond patterns and their frequency of rearangment/amplification for diagnostic entities within those patterns are summarized below.

FISH Results by Morphological Pattern and Diagnosis

PATTERN	DIAGNOSIS
HGRCS	EWS/PNET N=23	PDSS N=5	ARMS N=6	RMS,NOS N=5	RCLS N=3	DSRCT N=2	NOS N=23
	EWS+ 96%	SYT+ 100%	FKHR+ 66%	FKHR+ 0%	CHOP+ 100%	EWS+ 100%	EWS+ 6%
				EWS+ 0%			SYT+ 0%
							CHOP+ 0%
							FUS+ 0%
							FKHR+ 0%
SSS	SS N=27	MPNST N=7	NOS N=13
	SYT+ 96%	SYT+ 0%	SYT+ 0%
LGMN	LGFMS N=11	Myxoma N=4	MFS N=4	MLPS N=5	NOS N=10
	FUS+ 91%	FUS+ 0%	FUS+ 0%	FUS+ 100%	FUS+ 0%
				CHOP+ 0%	CHOP 0%
MN	CCS N=8	Melanoma N=11
	EWS+ 88%	EWS+ 0%
AN	Lipoma N=11	WDLPS N=4	DDLPS N=4	PLPS N=1
	MDM2+ 0%	MDM2+ 100%	MDM2+ 100%	MDM2+ 0%
	FUS+ 0%	FUS+ 0%
	CHOP+ 0%

EWS/PNET=Ewing's Sarcoma/Peripheral Neuroectodermal Tumor; PDSS=Poorly differentiated synovial sarcoma; ARMS=Alveolar rhabdomyosarcoma; RMS,NOS=Rhabdomyosarcoma not otherwise specified; RCLS=Round cell liposarcoma; DSRCT=Desmoplastic small round cell tumor; NOS=Not otherwise specified; SS=Synovial Sarcoma; MPNST=Malignant peripheral nerve sheath tumor; LGFMS=Low grade fibromyxoid sarcoma; MFS=myxofibrosarcoma; MLPS=myxoid liposarcoma; CCS=clear cell sarcoma; WDLPS=Well-differentiated liposarcoma; DDLPS=Dedifferentiated liposarcoma; PLPS=Pleomorphic Liposarcoma


Conclusions: FISH (using paraffin-embedded tissue) is a frequently utilized sensitive and specific tool for the diagnosis of soft tissue sarcomas, allowing one to distinguish between entities with overlapping morphologic and immunohistochemical features, which often have implications for treatment and prognosis (SS vs. MPNST, CCS vs. metastatic melanoma, lipoma vs. WDLPS, etc.).
Category: Bone & Soft Tissue

Monday, March 9, 2009 1:00 PM

Poster Session II # 13, Monday Afternoon