title: Sinonasal adamantinoma-like Ewing sarcoma: A case report.
abstract: We describe the case of a sinonasal adamantinoma-like Ewing sarcoma in a 41-year-old male. Histologically, the tumor exhibited distinctive areas of nested growth pattern with prominent stromal fibrosis and metaplastic bone formation. The tumor cells were small and uniform with minimal amount of pale eosinophilic to clear cytoplasm and round or oval nuclei with finely dispersed chromatin and small nucleoli. Approximately 20% of the tumor parenchyma comprised of small clusters of basaloid cells within an osteofibrous background resembling adamantinoma. The tumor showed strong expression of keratins, p63, CD99 and Fli-1, and EWSR1 rearrangement. The diagnosis of sinonasal Ewing family tumors is particularly problematic owing to the large number of potential mimics. For any poorly differentiated or undifferentiated head and neck tumor, cellular monotony and CD99 immunoreactivity should prompt consideration for molecular studies that include analysis of both EWSR1 and FLI1, even in the presence of strong cytokeratin expression or focal keratinization.
authors.affiliation: Department of Pathology, Northwestern University Feinberg School of Medicine, Northwestern Memorial Hospital, 251 East Huron St, Feinberg 7-342A, Chicago, IL 60611, United States. Electronic address: Borislav.Alexiev@northwestern.edu.
authors.forename: Borislav A
authors.initials: BA
authors.lastname: Alexiev
authors.affiliation: Department of Radiology, Northwestern University Feinberg School of Medicine, Northwestern Memorial Hospital, 676 N. St Clair, Suite 800, Chicago, IL, 60611, United States.
authors.forename: Yanki
authors.initials: Y
authors.lastname: Tumer
authors.affiliation: Department of Pathology, The Johns Hopkins University School of Medicine, 401 N. Broadway, Weinberg 2249, Baltimore, MD 21231, United States.
authors.forename: Justin A
authors.initials: JA
authors.lastname: Bishop
mesh_terms: D050398:Adamantinoma / Q000235:genetics / Q000473:pathology; D000328:Adult; D014408:Biomarkers, Tumor / Q000032:analysis; D002148:Calmodulin-Binding Proteins / Q000235:genetics; D015321:Gene Rearrangement; D006801:Humans; D007150:Immunohistochemistry; D017404:In Situ Hybridization, Fluorescence; D008297:Male; D009296:Nasal Cavity / Q000473:pathology*; D009669:Nose Neoplasms / Q000235:genetics / Q000473:pathology*; D015514:Oncogene Proteins, Fusion / Q000235:genetics; D034802:RNA-Binding Protein EWS; D016601:RNA-Binding Proteins / Q000235:genetics; D012512:Sarcoma, Ewing / Q000235:genetics / Q000473:pathology*
chemical_list: D014408:Biomarkers, Tumor; D002148:Calmodulin-Binding Proteins; C500986:EWSR1 protein, human; D015514:Oncogene Proteins, Fusion; D034802:RNA-Binding Protein EWS; D016601:RNA-Binding Proteins
keywords: Adamantinoma-like Ewing sarcoma; Sinonasal