[1229] Ewing Family of Tumors of the Sinonasal Tract

S Hafezi, RR Seethala, EB Stelow, S Mills, B Perez-Ordonez, I Leong, JL Hunt, I Weinreb. University Health Network, Toronto, ON, Canada; University of Pittsburgh Medical Center, Pittsburgh, PA; University of Virginia Health System, Charlottesville, VA; Massachusetts General Hospital, Boston, MA

Background: Ewing family of tumors (EFT) are malignant neoplasms typically arising in bone and soft tissue of children and young adults. Occasional cases have been described in the sinonasal tract. Most of these have not had molecular confirmation. EFT is known for its morphologic and immunohistochemical variability making this diagnosis challenging in this location. A large series of EFT in the sinonasal tract is lacking.
Design: Cases of EFT were retrieved from the archives of the authors institutions and reviewed. PAS and PASD were available as well in most cases. Immunohistochemical stains for keratins, CD99, S100, synaptophysin, p63, desmin and myogenin were performed. One case had previously been tested with RT-PCR for EWS-FLI1. Fluorescence in-situ hybridization (FISH) was performed in cases with available tissue.
Results: Twelve cases were identified including 6 males and 6 females ranging from 7-69 yrs (mean 30.7 yrs). Tumors were left sided (4), right sided (4), bilateral (1) and unspecified (3). They presented with nasal obstruction and occured in one or more sinuses (6), nasal cavity (3) or both (3). Sinuses involved were maxillary (5), ethmoid (4) and sphenoid (2). Five cases involved orbit or dura. Nine cases invaded bone. EFT's were composed of nests, cords and sheets of small round cells with variable cytoplasmic clearing and small nucleoli. Minimal mitotic activity was present. Four cases had necrosis. Many cases showed nesting with intervening fibrovascular stroma mimicking a carcinoma or esthesioneuroblastoma. Three cases had pericellular pink material highlighted with PAS. The tumors were positive for CD99 (12/12) and focally for keratins (4/11), synaptophysin (5/9) and S100 (2/9). All cases were negative for desmin, myogenin and p63. One case showed an EWS-FLI1 fusion by RT-PCR and an additional 6 cases were positive for EWS rearrangement by FISH. No material was available in the remaining cases. Follow up in 6 cases ranging from 1-26 months showed 1 patient dead of local and distant disease (breast), 1 patient dead with local disease, 1 patient alive with lung mets and the remainder disease free.
Conclusions: EFT is an aggressive disease of the sinonasal tract with a great degree of histological diversity. It shows a greater tendancy for nesting than its soft tissue counterpart.
Category: Head & Neck

Wednesday, March 24, 2010 9:30 AM

Poster Session V # 161, Wednesday Morning

 

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