Medulloblastoma with myogenic and/or melanotic differentiation does not align immunohistochemically with the genetically defined molecular subgroups.

Medulloblastoma with myogenic and/or melanotic differentiation does not align immunohistochemically with the genetically defined molecular subgroups.

Hum Pathol. 2018 Feb 02;:

Authors: Gupta K, Jugunoori S, Satapathy A, Salunke P, Kumar N, Radotra BD, Vasishta RK

Abstract
The World Health Organization classification of central nervous system neoplasms (2016 update) recognizes four histological variants and genetically defined molecular subgroups within medulloblastoma (MB). MB with myogenic differentiation is one of the rare variant which is usually recognized as a pattern alongside the known histological variants. Due to its rarity, less is known about its molecular landscape and importantly about its placement in the current molecular schema. We aimed to analyze this rare variant for expression of three immunohistochemical markers conventionally used in molecular stratification of MB. Demographic profile, imaging details with survival outcome was also analyzed. Sixty-five MB cases were molecularly stratified using immunohistochemical markers (YAP1, GAB1, β-catenin). MB with myogenic differentiation and MB cases showing variable immunoreactivity with above three antibodies were further evaluated for SMA, desmin, myogenin and HMB45. Seven cases were categorized as MB with myogenic and/or melanotic differentiation. Age ranged from 2-40years with M:F ratio of 1:1.3. In four cases, myogenic or melanotic differentiation was evident on histology, while in three, differentiation was highlighted only with muscle markers. Interestingly, all seven cases showed variable immunoreactivity with three molecular markers and did not follow the conventionally accepted algorithm used for molecular stratification. Follow-up period ranged from 9-57months. Overall survival revealed a varied pattern, with three deaths and four patients being alive with no evidence of disease at last follow-up. Our results provide evidence that these variants are distinct and do not align immunohistochemically with the currently recognized genetic subgroups.

PMID: 29412177 [PubMed - as supplied by publisher]

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