Gliomatosis cerebri with leptomeningeal spread and negative biopsy a diagnostic challenge

Age: 70 years Sex: Male Chief complaint: Generalized tonic-clonic seizure starting in the left lower limb

• No drug allergies
• No significant past medical history
• Former smoker (80 pack-years, quit 10 years ago)

Patient experienced a seizure at home, starting as left leg myoclonus, then progressing to generalized tonic-clonic convulsions with postictal rigidity. Upon evaluation, neurological examination was normal, with preserved strength, sensation, and gait.

Initial head CT revealed a parasagittal right parietal lesion. MRI further characterized this lesion with complex findings suggesting a high-grade glioma with gliomatosis pattern and leptomeningeal dissemination.

• Alert and oriented
• Cranial nerves intact
• Normal strength and sensation
• Normal gait

CT brain scan:

• Right parasagittal parietal hypodense lesion (27 x 22 x 22 mm)
• Peripheral ring enhancement
• Small satellite lesions
• Mild mass effect, no midline shift or hydrocephalus

Brain MRI:

• Cortico-subcortical lesion (3 x 2.5 x 2.8 cm) with necrotic center
• Ring enhancement and leptomeningeal/dural spread
• Restricted diffusion and elevated rCBV (up to 4.0)
• Satellite nodules and infiltrative areas extending periventricularly, transcallosally, and ependymally
• Suggestive of high-grade glioma with gliomatosis cerebri features and dissemination

Thoracoabdominal-pelvic CT with contrast:

• No extracranial neoplastic lesions
• Incidental findings: sigmoid diverticulosis, lumbar spondylolisthesis

Histopathological results:

• Reactive gliosis
• NO evidence of neoplastic cells

Imaging findings are highly suggestive of high-grade primary glial tumor (likely glioblastoma with gliomatosis features), despite negative biopsy.

Possible reasons for false-negative biopsy:

• Sampling error (biopsy not representative of high-grade component)
• Predominantly infiltrative tumor with low cellularity in sampled area

• Correlate with advanced MRI and perfusion maps
• Consider second biopsy targeting area with highest rCBV and diffusion restriction
• Alternatively, proceed with empirical treatment as high-grade glioma
• CSF study (cytology, cfDNA, molecular markers) recommended
• Close clinical and radiological follow-up

• Monitor neurological status
• Antiepileptic treatment for seizure control
• Await full committee discussion before definitive management