[356] The Contribution of Fluorescence In-Situ Hybridization (FISH) Studies to the Fine-Needle Aspiration Biopsy (FNAB) of Soft Tissue and Bone Neoplasms

M Bansal, G Cai, WK Khalbuss. University of Pittsburgh, Pittsburgh, PA

Background: The diagnosis of soft tissue and bone neoplasms by fine-needle aspiration biopsy (FNAB) can be challenging due to overlapping cytomorphologic features. Molecular studies can be particularly helpful to render a specific diagnosis by detecting characteristic chromosomal translocations, or to provide prognostic or therapy-related information to the clinician. The goal of this study is to determine if fluorescence in-situ hybridization (FISH) studies performed on cytologic material can be useful in the diagnosis and management of soft tissue and bone lesions.
Design: Between January 2004 and December 2007, 862 cases of soft tissue and bone were diagnosed by FNAB at our institution. FISH studies were performed in 85 cases (10%). We retrospectively reviewed these cases to see if the outcome of the FISH studies had additional value to the cytomorphologic analysis and other ancillary studies. The FISH studies were primarily performed on unstained direct aspirate smears, or occasionally on cell block sections and the results were classified as positive, negative, or inadequate for diagnosis.
Results: The 85 cases with FISH studies included 42 cases of hematopoietic tumors, 25 cases of mesenchymal tumors, and 18 cases of metastatic breast carcinoma. The indications for performing FISH studies were for tumor subclassification (67 cases, 79%) and detection of HER2/neu gene amplification (18 cases, 21%). The most common requested FISH studies were the IgH gene rearrangement for hematopoietic malignancies and t(12;16), t(12,22)/CHOP-TLC and t(11;22)/EWSR1 for mesenchymal malignancies. Of the 85 cases, FISH was positive in 37 (44%) cases, negative in 45 (53%) cases and inadequate in 3 (3%) cases. Of the 67 cases submitted for further tumor classification, 32 cases (48%) were successful in subclassifying the tumors. Of the 18 cases of metastatic breast carcinoma submitted for HER2/neu FISH, 16 cases (19%) were successful in determining the HER2/neu status.
Conclusions: This study illustrates that FISH studies performed on cytologic material can be advantageous as an ancillary technique in the diagnosis and management of soft tissue and bone lesions. Therefore, the preparation of adequate unstained smears or other material for the studies can be important when the FNABs are performed.
Category: Cytopathology

Wednesday, March 11, 2009 1:00 PM

Poster Session VI # 55, Wednesday Afternoon