Utilization of CD99 as Diagnostic Marker for Ependymomas and Demonstration of Microlumen Wwith Microvilli in Ependymomas by Electron Microscopy. (21st September 2018)

• Record Type: Journal Article
• Authors: Farooq, Taliya; Gilani, Sarwat; Kleinman, George; Khan, Azkia
• Is Part Of: American journal of clinical pathology. Volume 150(2018)Supplement 1
• Page Start: S8
• Page End: S8
• Publication Date: 2018-09-21
• Subjects: Diagnosis, Laboratory -- Periodicals; Pathology -- Periodicals; 616.07
• DOI: 10.1093/ajcp/aqy090.019
• Languages: English
• ISSNs: 0002-9173

Abstract

Abstract: Objectives: Ependymoma is a tumor of the central nervous system (CNS) that may be located in the brain or spinal cord. Ependymomas exhibit multiple histologic patterns. The cellularity and architecture of ependymomas vary considerably from case to case. The histologic variants of ependymomas are classified according to the WHO into the following types: subependymoma and myxopapillary ependymoma (grade 1), low grade (grade 2), and anaplastic (grade 3). Immunohistochemistry (IHC) can help in differentiating ependymomas from other nonependymal tumors. So far, GFAP and vimentin often have been used for distinguishing ependymomas from other CNS tumors. Nevertheless, a panel of antibodies is usually required for an accurate final diagnosis. So our aim of this study was to establish the role of CD99 as a diagnostic marker for ependymomas and subependymomas. Methods: Ependymomas (n = 26) and subependymomas (n = 2), including brain (n = 20) and spinal cord (n = 8), were retrieved from LIS of one institute, including 19 cases from males and 9 cases from females. An expert neuropathologist confirmed the prior diagnosis. Representative sections from each case were subjected to IHC stain for CD99 (Cell Marque, 1:100 dilution), GFAP (Cell Marque, 1:100 dilution), and EMA (Sigma, 1:100 dilution). Electron microscopy was also performed in all cases. Results: Twenty-four out of all 26 ependymomas showed positive membranous and intracytoplasmic dot-like CD99 immunoreactivity. The immunostain for CD99 disclosed the presence of intensely immunopositive cytoplasmic deposits, possibly microlumens. Electron microscopy findings also confirmed same findings. IHC results for other antigens are as follows: Subtypes of Tumor CD99 Positivity EMA Positivity GFAP Positivity Ependymomas 24/26 (92%) 4/24 (16%) 21/26 (81%) Subependymomas 2/2 (100%) 1/2 (50%) 2/2 (100%) Conclusion: This study emphasizes the importance of CD99 as a diagnostic marker in differentiating between ependymal and nonependymal tumors, particularly the strongly stained membranous or dot-like cytoplasmic pattern. EMA cannot be helpful in this context.