SMARCA4-associated malignant rhabdoid tumors: case report and literature review

Abstract

Malignant rhabdoid tumor (MRT) is a rare malignant neoplasm of childhood, characterized by an aggressive course and an extremely unfavorable prognosis. The frequency of MRT outside the central nervous system (extracranial MRT) is 0.02–0.03 per 100,000 children. In most cases, MRT is based on an inactivating mutations of the tumor suppressor gene SMARCB1, which leads to the absence of expression of the SMARCB1 ((INI1/hSNF5/BAF47) protein in tumor cells. Aberrations of the SMARCA4 gene, which is an extremely rare molecular event, have been described among the MRTs expressing SMARCB1 (INI1). Few case reports have been described in the international literature.This article contains a description of a clinical case of a patient diagnosed with soft tissue MRT with SMARCA4 gene alteration. The distinctive features of the presented case are the congenital nature of the tumor, atypical localization, and extremely aggressive clinical course of the disease. On the example of the described clinical case, diagnostics of SMARCA4-associated MRT are presented, as well as the place of molecular methods in diagnosis verification. In addition, it is highlighted that the detection of somatic changes in the SMARCB1 and SMARCA4 genes requires additional investigation of their germinal status to exclude or confirm the rhabdoid tumor predisposition syndrome.