Hyaline eosinophilic astrocytic inclusions in two children with drug-resistant epilepsy—Case reports and literature review

Abstract

Introduction: Hyaline eosinophilic astrocytic inclusion (HEAI) is a rare histological finding in cases with drugresistant epilepsy (DRE). Objectives: To describe two cases of DRE with HEAI and review the literature. Patients and Methods: Case 1: A 5-year-old boy with a history of DRE since 5 months of age and global developmental delay, nonverbal (GDD, NV). MRI revealed signs of polymicrogyria, involving the right frontal operculum with an abnormal cortical folding and rotation pattern. The genetic panel showed a variant of uncertain significance in the SCL2A1 gene. Outcome: Engel IV-B. Case 2: A 5-year-old boy with a history of DRE since 4 months of age and GDD, NV. MRI showed abnormal cortical folding and cortical thickening in the right frontal lobe. Genetic testing demonstrated a variant of uncertain significance in the ADAR gene. Outcome: Engel IV-A. Resection of the lesion was performed in both patients. Results: Both cases showed brightly eosinophilic structures within the astrocytic cytoplasm in the gray matter and FCD type 2A. The inclusions were negative with PAS and Congo red. By immunohistochemistry, they were positive for S100 and negative for vimentin, and GFAP. We also analyzed the data of all the previously reported cases. Conclusion: HEAI is a rare entity, with only 53 cases reported, including our cases. Evaluating all the cases, the average age at seizure onset of pediatric patients (n = 48) was 7 months, without sex predilection. Seven patients had Aicardi syndrome, and 23 patients presented GDD. Seizures were observed in 47 patients. Outcome Engel: I in 10 cases, II in 5, III in 9, and IV in 9. Most cases involved the frontal lobe (n = 40). HEAIs were positive for S100 in 21/25 (84%), filamin in 22/25 (88%), GFAP in 3/32 cases (9%), vimentin in 1/16 (6%), and PAS in 3/21 (14%). FCD was observed in 19/50 patients (38%). The significance of HEAI is not clear. Genetic studies of the surgical specimens will probably allow a better comprehension of this entity.