Low-grade small round cell tumor of the cauda equina with EWSR1-WT1 fusion and indolent clinical course

Nasir Ud Din; Melike Pekmezci; Gohar Javed; Andrew E Horvai; Zubair Ahmad; Muhammad Faheem; Anthony L Navarro; Dolores López-Terrada; Arie Perry

doi:10.1016/j.humpath.2014.09.015

Low-grade small round cell tumor of the cauda equina with EWSR1-WT1 fusion and indolent clinical course

Hum Pathol. 2015 Jan;46(1):153-8. doi: 10.1016/j.humpath.2014.09.015. Epub 2014 Oct 18.

Authors

Nasir Ud Din¹, Melike Pekmezci², Gohar Javed³, Andrew E Horvai², Zubair Ahmad⁴, Muhammad Faheem³, Anthony L Navarro⁵, Dolores López-Terrada⁵, Arie Perry⁶

Affiliations

¹ Department of Pathology and Microbiology, Section of Histopathology, Aga Khan University Hospital, Karachi Pakistan. Electronic address: nasir.uddin@aku.edu.
² Department of Pathology, University of California San Francisco (UCSF), San Francisco, CA, 94143.
³ Department of Neurosurgery, Aga Khan University Hospital, Karachi Pakistan.
⁴ Department of Pathology and Microbiology, Section of Histopathology, Aga Khan University Hospital, Karachi Pakistan.
⁵ Departments of Pathology and Pediatrics, Texas Children's Hospital and Baylor College of Medicine, Houston, TX, 77030.
⁶ 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.

PMID: 25454478
DOI: 10.1016/j.humpath.2014.09.015

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.

Keywords: Bilateral; Desmoplastic small round cell tumor; EWSR1; EWSR1-WT1; Glomus tumor; Spinal nerves.

Publication types

Case Reports

MeSH terms

Adult
Biomarkers, Tumor / analysis
Biomarkers, Tumor / genetics*
Biopsy
Calmodulin-Binding Proteins / genetics*
Cauda Equina / chemistry
Cauda Equina / pathology*
Cauda Equina / surgery
Cell Differentiation
Gene Fusion*
Genetic Predisposition to Disease
Glomus Tumor / chemistry
Glomus Tumor / genetics*
Glomus Tumor / pathology
Glomus Tumor / surgery
Humans
Immunohistochemistry
In Situ Hybridization, Fluorescence
Ki-67 Antigen / analysis
Magnetic Resonance Imaging
Male
Mitotic Index
Neoplasm Grading
Peripheral Nervous System Neoplasms / chemistry
Peripheral Nervous System Neoplasms / genetics*
Peripheral Nervous System Neoplasms / pathology
Peripheral Nervous System Neoplasms / surgery
Phenotype
RNA-Binding Protein EWS
RNA-Binding Proteins / genetics*
Reverse Transcriptase Polymerase Chain Reaction
Treatment Outcome
Tumor Burden
WT1 Proteins / genetics*

Substances

Biomarkers, Tumor
Calmodulin-Binding Proteins
EWSR1 protein, human
Ki-67 Antigen
RNA-Binding Protein EWS
RNA-Binding Proteins
WT1 Proteins
WT1 protein, human