%0 Journal Article
%T Spontaneous Regression of Atypical Teratoid Rhabdoid Tumor Without Therapy in a Patient With Uncommon Regional Inactivation of SMARCB1 (hSNF5/INI1)
%A Abhishek Bavle
%A Adekunle M Adesina
%A Carrie A Mohila
%A Jack M Su
%A Jo Elle G Peterson
%A Ronald A Rauch
%A Vidya P Mehta
%A William E Whitehead
%J Pediatric and Developmental Pathology
%@ 1615-5742
%D 2019
%R 10.1177/1093526618814696
%X Atypical teratoid/rhabdoid tumor (ATRT) is a high-grade central nervous system tumor, with poor prognosis despite intensive multimodal therapy. Loss of nuclear immunostaining for INI1 due to inactivation of the hSNF5/INI1 tumor suppressor gene is pathognomonic of ATRT. We present a patient with congenital ATRT, who had spontaneous tumor regression without therapy, and is disease-free 4 years later. Tumor histopathology showed rhabdoid cells characteristic of ATRT, but immunohistochemistry revealed heterogeneous loss of nuclear INI1 staining. The populations of INI1-intact and INI1-deficient cells were separated by laser microdissection, for molecular analysis with DNA sequencing and fluorescence in situ hybridization. The INI1-negative cells were found to harbor a heterozygous deletion and truncating mutation of the hSNF5/INI1 locus, while the INI1-intact cells had 2 copies of the wild-type INI1 gene. To our knowledge, this is the first report of spontaneous regression of ATRT, with molecular heterogeneity for SMARCB1 inactivation, with no radiographic signs of recurrence at 4 years after diagnosis
%K focal inactivation
%K SMARCB1
%K INI1
%K atypical teratoid rhabdoid tumor
%K spontaneous regression
%U https://journals.sagepub.com/doi/full/10.1177/1093526618814696