Abstract
BACKGROUND: Diffuse leptomeningeal glioneuronal tumor (DLGNT) is a rare central nervous system tumor, especially in adult females. Typically, it presents with leptomeningeal enhancements in the basal cisterns and spinal cord. However, varied radiological and pathological features can complicate the diagnosis, as the present case illustrates. OBSERVATIONS: An adult female presented with severe headache, blurred vision, and cognitive impairment. Elevated intracranial pressure (ICP) was detected via lumbar puncture. Brain magnetic resonance imaging (MRI) revealed atypical unilateral basal cistern enhancement, differing from the usual symmetrical DLGNT presentation. Despite high ICP, only mild ventricular enlargement was observed. Noncontrast spine MRI failed to demonstrate spinal leptomeningeal enhancement. A stereotactic biopsy of an occipital lesion was inconclusive. These atypical findings led to misdiagnoses of viral encephalitis or inflammation at two hospitals. Significant symptom relief occurred only after ventriculoperitoneal (VP) shunt surgery. Over 2.5 years, intraparenchymal lesions in the parahippocampal gyrus grew, necessitating surgical intervention. Pathological examination finally confirmed DLGNT. Postsurgery, the patient underwent chemotherapy with temozolomide and remains symptom free. LESSONS: This case underscores the critical importance of comprehensive initial imaging, strategic biopsy planning, and timely placement of a VP shunt in patients with DLGNT. It contributes to the literature by revealing atypical imaging features and long-term progression patterns of DLGNT. https://thejns.org/doi/10.3171/CASE24701.