Please select Print from the file menu or right mouse click and choose print from the menu to print this page.

[429] FUS Flourescence In-Situ Hybridization Is Useful for Differentiating Cutaneous Low-Grade Fibromyxoid Sarcoma from Other Superficial Fibromyxoid Neoplasms

RM Patel, E Downs-Kelly, JC Fanburg-Smith, SD Billings, RR Tubbs, JR Goldblum. The Cleveland Clinic, Cleveland, OH; Armed Forces Institute of Pathology, Washington, DC; Indiana University School of Medicine, Indianapolis, IN

Background: Low-grade fibromyoxid sarcomas (LGMFS) are rare, typically deep soft tissue neoplasms which have deceptively bland cytology and the potential to metastasize. A t(7;16)(q34;p11) FUS-CREB3L2 has been identified in approximately 80-90% of deep soft tissue LGFMS. Cutaneous fibromyxoid neoplasms are not uncommon, but dermatopathologists rarely consider LGFMS since this lesion is so uncommon in the skin. We identified a subset of superficial LGFMS and a spectrum of neoplasms within the differential and performed fluorescence in-situ hybridization (FISH) to evaluate the utility of FUS rearrangement in the workup of cutaneous fibromyxoid neoplasms.
Design: FISH for chromosomal rearrangement of FUS (16p11) (Abbott Molecular/Vysis, Des Plaines,IL) using a dual color break-apart format probe was performed on formalin-fixed, paraffin-embedded tissue (FFPET) sections from superficial LGFMS (n=6), myxomas (n=10), and myxofibrosarcoma/myxoid malignant fibrous histiocytomas (myxoid MFH) (n=5). 100 non-overlapping tumor nuclei per case were evaluated for evidence of either fused (normal) or split (translocated) signals.
Results: Of the LGFMS, 4/6 (67%) showed a rearrangement of FUS (range: 72-80% positive nuclei per 100 nuclei). One of the two FUS-negative cases was composed predominantly of areas resembling hyalinizing spindle cell tumor with giant rosettes. The other neoplasms within the differential were devoid of any rearrangement involving FUS (range: 0-2% positive nuclei per 100 nuclei).
Conclusions: Our observed frequency of FUS rearrangement in superficial LGFMS is consistent with those published in the literature for more deeply seated lesions. When applied to suspicious superficial myxoid or fibromyxoid neoplasms, the FUS FISH probe in FFPET can be a useful ancillary technique for diagnosis of this uncommon and deceptively bland tumor.
Category: Dermatopathology

Monday, March 26, 2007

Poster # 67, Monday Morning