Progression-Associated Loss of SMARCB1/INI1 Expression in Mismatch Repair-Deficient Glioblastoma.
Enrico Küllenberg, Nils Warneke, Markus Holling et al.
✦ AI-curated · Sources linked
Case in brief
A patient with mismatch repair-deficient glioblastoma had a recurrent tumor in which testing identified a second SMARCB1 mutation and complete loss of SMARCB1/INI1 protein expression. The report describes this change as occurring with tumor progression. The finding highlights that SMARCB1 status may differ between the original and recurrent tumor, with implications for interpreting pathology at recurrence.
What made this case unusual
Complete loss of SMARCB1/INI1 expression emerged alongside an acquired second SMARCB1 mutation in a mismatch repair-deficient glioblastoma at recurrence, creating a potential diagnostic pitfall.
Diagnostic / clinical pearl
In mismatch repair-deficient glioblastoma, assess SMARCB1/INI1 expression in the recurrent tumor rather than assuming it is unchanged from the original tumor.