EP14.04 ERDHEIM-CHESTER DISEASE WITH CENTRAL NERVOUS SYSTEM INVOLVEMENT: A RARE CASE REPORT

Abstract OBJECTIVE Erdheim Chester disease (ECD) is a rare form of non-Langerhans cell histiocytosis. ECD is characterized by the infiltration of various organs by foamy CD68+ and CD1a- histiocytes. Although ECD primarily affects the skeletal system, it may involve multiple organs, with central nervous system (CNS). The most common neurological symptoms are cognitive difficulty, cerebellar ataxia, cranial neuropathy, pyramidal tract involvement, and seizures. Therapeutic options for ECD include BRAF inhibitors, MEK inhibitors, and interferon-α. Glucocorticoids and localized radiotherapy may be used as adjunctive therapies to manage acute central nervous system (CNS) symptoms. This paper review on the diagnostic and therapeutic challenges associated with the treatment of Erdheim Chester disease (ECD) CASE We present the case of a 71-year-old man with chronic progressive cephalalgia on the left side, gradual right-sided weakness, acute anomic aphasia, and cognitive decline over the same period. A head magnetic resonance imaging revealed findings suggestive of glioblastoma. Patient had maximal tumor resection and histopathological examination showed anaplastic cell proliferation with round to oval pleomorphic nuclei, coarse chromatin, and vacuolated cytoplasm, along with vascular proliferation, lymphocytic infiltration, and a high mitotic index (10/10 HPF). These features were suggestive of anaplastic astrocytoma. Immunohistochemical staining revealed GFAP positivity in glial cells; CD68 positivity in histiocytes; CD45, CD3, and CD20 expression in lymphocytes and a Ki-67 proliferation index of 5%. CD1a was negative. Patient was diagnosed Erdheim-Chester Disease. CONCLUSION The patient was initially diagnosed with glioblastoma, based on both radiological imaging and histopathological examination. However, subsequent histochemical analysis revealed GFAP positivity in glial cells, CD68 positivity in histiocytes, and CD45, CD3, and CD20 expression in lymphocytes, findings that were more consistent with a diagnosis of Erdheim-Chester Disease. This case underscores the need for thorough diagnostic workup in atypical CNS lesions to avoid misdiagnosis and ensure proper treatment selection. Keywords: Erdheim-Chester Disease, Central Nervous System, Histiocytosis, Clinician Evaluation