Subependymal giant cell astrocytoma, hereditary versus solitary: clinical, morphological, and immunophenotypic characterization

Objective: To compare clinicopathological characteristics of patients with solitary subependymal giant cell astrocytoma (SEGA) at our institution, with those associated to tuberous sclerosis complex (TSC). Methods: It was a descriptive-retrospective study of surgically treated SEGA patients (2013-2022). Demographic and clinical data were obtained. An immunohistochemistry (IHC) panel was applied: GFAP, neurofilaments, hamartin, tuberin, Ki67, nestin, OCT-4, INI-1, STAT-6, CK-AE1/ AE3, TTF1, and YAP-1. Descriptive statistical was used. Results: 4 patients were studied: Two women, 23 and 25 years old, diagnosed as TSC patients at 10 and 12 years of age, and two men with solitary SEGA (18 and 46 years old). Tumors were positive to GFAP, NF, nestin, and TTF1. Cytoplasmic STAT6 and CK stains was observed in all patients. 2/4 cases showed YAP-1 nuclear expression. TSC patients retained INI-1 nuclear expression, while solitary SEGAs lost it. Conclusions: SEGA is a glioneuronal tumor that expresses markers of neuroepithelial stem cells and cytokeratins. Its diagnosis must be supported with a minimal IHC panel: GFAP, neurofilaments, synaptophysin, nestin and TTF1. Morphological differences were observed between the TSC related and solitary SEGAs and in INI1 expression. Nuclear expression of YAP-1 in 2/4 tumors, opens the possibility of research for combined use of YAP and mTOR regulators in the management of SEGA.