Clinical Report: Primary Diffuse Leptomeningeal Glioblastoma Case Study

Overview

This report describes a rare case of glioblastoma presenting exclusively as diffuse leptomeningeal disease without a dominant parenchymal mass. A 72-year-old woman exhibited progressive neurological decline with extensive leptomeningeal enhancement on MRI and was diagnosed via biopsy as IDH-wildtype glioblastoma, CNS WHO grade 4.

Background

Glioblastoma (GBM) is the most common malignant primary brain tumor in adults, typically presenting as a dominant parenchymal lesion. Leptomeningeal disease (LMD) secondary to leptomeningeal spread (LMS) is a rare complication of GBM, usually occurring during recurrence (secondary LMS). Primary LMS, where leptomeningeal involvement is present at initial diagnosis without a parenchymal mass, is extremely rare and not well documented. This case highlights the diagnostic challenges and clinical features of primary diffuse leptomeningeal GBM.

Data Highlights

Key Findings

• Patient presented with progressive imbalance, confusion, bilateral lower extremity weakness, and urinary retention without headaches or focal cranial nerve deficits.
• MRI revealed extensive intracranial and spinal leptomeningeal enhancement without a dominant parenchymal mass lesion.
• CSF analysis showed grossly elevated protein and lactate but was acellular with inconclusive cytology and flow cytometry.
• Open biopsy of a Sylvian fissure leptomeningeal nodule confirmed IDH-wildtype glioblastoma, CNS WHO grade 4, with astrocytic morphology and microvascular proliferation.
• The tumor exhibited a diffusely infiltrative growth pattern involving superficial cortex and leptomeninges.
• Standard GBM treatment protocols are challenged by the absence of a resectable parenchymal mass and extensive leptomeningeal involvement.

Clinical Implications

Clinicians should consider primary leptomeningeal glioblastoma in patients presenting with diffuse leptomeningeal enhancement and neurological decline even in the absence of a dominant brain mass. Diagnosis may require open biopsy due to inconclusive CSF studies. Treatment strategies need to be adapted given the diffuse leptomeningeal involvement and poor prognosis associated with this rare presentation.

Conclusion

Primary diffuse leptomeningeal glioblastoma is an exceptionally rare and diagnostically challenging entity that can present without a dominant parenchymal tumor. Awareness and early biopsy are critical for diagnosis and guiding management in such atypical GBM presentations.

References

1. Epidemiology and Standard of Care for Glioblastoma
2. Leptomeningeal Spread in Glioblastoma: Incidence and Prognosis
3. Case Report: Primary Leptomeningeal Glioblastoma Presentation and Diagnosis