title: Low-grade small round cell tumor of the cauda equina with EWSR1-WT1 fusion and indolent clinical course.
abstract: We report a case of a longstanding, large tumor involving spinal nerve roots of the cauda equina. The tumor showed small round cells arranged in nests and cords and immunophenotypic features of a glomus tumor, along with infrequent mitoses and a low Ki-67 labeling index, but exhibited some rosette-like structures, with focal CD99 and Neu-N expression. Subsequent molecular analysis showed the presence of an EWSR1-WT1 gene fusion by fluorescence in situ hybridization, which was confirmed by reverse- transcriptase polymerase chain reaction. To our knowledge, this is the first case reported with EWSR1-WT1 fusion in a small round blue cell tumor with smooth muscle differentiation and an indolent course.
authors.affiliation: Department of Pathology and Microbiology, Section of Histopathology, Aga Khan University Hospital, Karachi Pakistan. Electronic address: nasir.uddin@aku.edu.
authors.forename: Nasir
authors.initials: N
authors.lastname: Ud Din
authors.affiliation: Department of Pathology, University of California San Francisco (UCSF), San Francisco, CA, 94143.
authors.forename: Melike
authors.initials: M
authors.lastname: Pekmezci
authors.affiliation: Department of Neurosurgery, Aga Khan University Hospital, Karachi Pakistan.
authors.forename: Gohar
authors.initials: G
authors.lastname: Javed
authors.affiliation: Department of Pathology, University of California San Francisco (UCSF), San Francisco, CA, 94143.
authors.forename: Andrew E
authors.initials: AE
authors.lastname: Horvai
authors.affiliation: Department of Pathology and Microbiology, Section of Histopathology, Aga Khan University Hospital, Karachi Pakistan.
authors.forename: Zubair
authors.initials: Z
authors.lastname: Ahmad
authors.affiliation: Department of Neurosurgery, Aga Khan University Hospital, Karachi Pakistan.
authors.forename: Muhammad
authors.initials: M
authors.lastname: Faheem
authors.affiliation: Departments of Pathology and Pediatrics, Texas Children's Hospital and Baylor College of Medicine, Houston, TX, 77030.
authors.forename: Anthony L
authors.initials: AL
authors.lastname: Navarro
authors.affiliation: Departments of Pathology and Pediatrics, Texas Children's Hospital and Baylor College of Medicine, Houston, TX, 77030.
authors.forename: Dolores
authors.initials: D
authors.lastname: López-Terrada
authors.affiliation: Department of Pathology, University of California San Francisco (UCSF), San Francisco, CA, 94143; Department of Neurological Surgery, University of California San Francisco, San Francisco, CA, 94143.
authors.forename: Arie
authors.initials: A
authors.lastname: Perry
mesh_terms: D000328:Adult; D014408:Biomarkers, Tumor / Q000032:analysis / Q000235:genetics*; D001706:Biopsy; D002148:Calmodulin-Binding Proteins / Q000235:genetics*; D002420:Cauda Equina / Q000737:chemistry / Q000473:pathology* / Q000601:surgery; D002454:Cell Differentiation; D050939:Gene Fusion; D020022:Genetic Predisposition to Disease; D005918:Glomus Tumor / Q000737:chemistry / Q000235:genetics* / Q000473:pathology / Q000601:surgery; D006801:Humans; D007150:Immunohistochemistry; D017404:In Situ Hybridization, Fluorescence; D019394:Ki-67 Antigen / Q000032:analysis; D008279:Magnetic Resonance Imaging; D008297:Male; D008940:Mitotic Index; D060787:Neoplasm Grading; D010524:Peripheral Nervous System Neoplasms / Q000737:chemistry / Q000235:genetics* / Q000473:pathology / Q000601:surgery; D010641:Phenotype; D034802:RNA-Binding Protein EWS; D016601:RNA-Binding Proteins / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016896:Treatment Outcome; D047368:Tumor Burden; D025721:WT1 Proteins / Q000235:genetics*
chemical_list: D014408:Biomarkers, Tumor; D002148:Calmodulin-Binding Proteins; C500986:EWSR1 protein, human; D019394:Ki-67 Antigen; D034802:RNA-Binding Protein EWS; D016601:RNA-Binding Proteins; D025721:WT1 Proteins; C583751:WT1 protein, human
keywords: Bilateral; Desmoplastic small round cell tumor; EWSR1; EWSR1-WT1; Glomus tumor; Spinal nerves