Spontaneous Regression of Atypical Teratoid Rhabdoid Tumor Without Therapy in a Patient With Uncommon Regional Inactivation of SMARCB1 (hSNF5/INI1). (March 2019)

• Record Type: Journal Article
• Authors: Peterson, Jo Elle G; Bavle, Abhishek; Mehta, Vidya P; Rauch, Ronald A; Whitehead, William E; Mohila, Carrie A; Su, Jack M; Adesina, Adekunle M
• Is Part Of: Pediatric and developmental pathology. Volume 22:Number 2(2019)
• Page Start: 161
• Page End: 165
• Publication Date: 2019-03
• Subjects: focal inactivation -- SMARCB1 -- INI1 -- atypical teratoid rhabdoid tumor -- spontaneous regression; Pediatric pathology -- Periodicals; Children -- Diseases -- Periodicals; Diagnosis, Laboratory -- Periodicals; Abnormalities, Human -- Periodicals; Child development -- Periodicals; Pediatrics -- Periodicals; 616.07
• DOI: 10.1177/1093526618814696
• Languages: English
• ISSNs: 1093-5266

Abstract

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.