A rare case of pythium brain infection presenting as severe neurological deterioration in a pediatric patient: A case report and literature review

Human pythiosis, caused by <i>Pythium insidiosum</i>, is a rare and often fatal infection that carries high morbidity, particularly when the central nervous system is affected. We describe a severe case in a 2-year-old boy from Saudi Arabia who was previously healthy and presented with a two-week history of intermittent fever, diplopia, and abnormal limb movements, which progressed to generalized seizures and rapidly worsening neurological deficits. Initial imaging demonstrated space-occupying lesions in the basal ganglia and thalamus with extensive edema and hydrocephalus, raising suspicion for neoplasm or meningoencephalitis. Surgical intervention with craniotomy and external ventricular drain insertion was performed. Histopathological examination revealed necrotizing granulomatous inflammation containing rare fungal hyphae demonstrated by silver staining, while microbiological studies confirmed <i>Pythium</i> species. Despite antifungal therapy and intensive supportive care, the patient's condition deteriorated, and he died due to extensive brain involvement. Review of published literature indicates that central nervous system pythiosis is exceedingly rare, typically associated with rapid progression and uniformly poor outcomes, even with combined surgical and medical management. This case emphasizes the importance of maintaining clinical suspicion in children with unusual space-occupying brain lesions, the need for rapid histopathological and molecular confirmation, and the limitations of currently available treatment options. Early recognition and development of more effective therapies are urgently required to improve survival in pediatric patients with this devastating condition.