[41] Solitary Fibrous Tumor: Is There a Molecular Relationship with Cellular Angiofibroma, Spindle Cell Lipoma and Mammary-Type Myofibroblastoma?

Karen J Fritchie, Yang Sun, Galina Batiouchko, Paula Carver, Steven D Billings, Brian P Rubin, Raymond R Tubbs, John R Goldblum. Mayo Clinic, Rochester, MN; Cleveland Clinic, Cleveland, OH

Background: Solitary fibrous tumor (SFT) is a distinct mesenchymal tumor characterized by ovoid to spindled cells, characteristic thick-walled branching (“staghorn”) blood vessels, stromal hyalinization, variable amounts of lipomatous differentiation and immunoreactivity for CD34. Recent studies have shown loss of 13q in a group of morphologically similar entities including cellular angiofibroma, mammary-type myofibroblastoma and spindle cell lipoma. The histologic and immunophenotypic overlap between solitary fibrous tumor and the latter group of tumors has been recognized, raising the possibility that all four of these tumors may be genetically linked.
Design: We tested a group of 40 SFTs including some malignant SFTs to assess for loss of RB1 (13q14) by fluorescence in situ hybridization (FISH). Additionally, a group of cellular angiofibromas (1 case), spindle cell lipomas (6 cases) and mammary-type myofibroblastomas (4 cases) were analyzed as a control group.
Results: All cases (38/38) of solitary fibrous tumor with evaluable signals failed to show loss of RB1 (13q14) by FISH while all cases of cellular angiofibroma (1/1), spindle cell lipoma (6/6) and mammary-type myofibroblastoma (4/4) showed either monoallelic or biallelic loss of RB1.
Conclusions: Although solitary fibrous tumor may share overlapping morphologic and immunophenotypic features with cellular angiofibroma, mammary-type myofibroblastoma and spindle cell lipoma, the absence of RB1 loss suggests that they are not related genetically.
Category: Bone & Soft Tissue

Tuesday, March 20, 2012 9:15 AM

Platform Session: Section G, Tuesday Morning


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