The Rare Phenomenon of Loss of INI1 Expression at Recurrence/Progression of Primary Central Nervous System Tumors: Report of 3 Cases. (May 2020)

• Record Type: Journal Article
• Authors: Sali, Akash Pramod; Chaubey, Vishal; Kodare, Duhita; Sahay, Ayushi; Epari, Sridhar
• Is Part Of: International journal of surgical pathology. Volume 28:Number 3(2020)
• Page Start: 341
• Page End: 347
• Publication Date: 2020-05
• Subjects: INI1 loss -- recurrent CNS tumors -- AT/RT -- SMARCB1/INI1; Pathology, Surgical -- Periodicals; 617.07
• DOI: 10.1177/1066896919883942
• Languages: English
• ISSNs: 1066-8969

Abstract

It is extremely rare for loss of immunohistochemical expression of INI1 to occur primarily at recurrence/progression with retained expression at the primary/initial presentation of central nervous system (CNS) tumor. In this article, we present 3 such cases showing loss of INI1 expression primarily at recurrence. All patients were males, aged 7 years (case 1), 11 years (case 2), and 35 years (case 3), diagnosed with low-grade glial/glioneuronal tumor, not otherwise specified (case 1), craniopharyngioma (case 2), and glioblastoma (case 3); all showed retained INI1 protein expression. Case 1 at 12 months recurrence showed a high-grade tumor with relative undifferentiated morphology, case 2 after 104 months showed a sarcomatous progression, and case 3 recurred after 4 months with the presence of relative undifferentiated round cells. All these recurrences showed loss of INI1 expression. Loss of SMARCB1/INI1 gene function resulting in complete loss of INI1 protein expression is not a well-accepted genetic mechanism for transformation/progression as this series emphasizes.