Cerebellar Lesion of Uncertain Etiology in a 63-Year-Old Male

We present the case of a 63-year-old male with a progressive cerebellar lesion under study since 2023. Despite two biopsy attempts, no definitive diagnosis was obtained. The patient underwent a third biopsy with neuronavigation and 5-ALA guidance in May 2025. This case highlights the diagnostic challenges of cerebellar lesions with atypical clinical and radiological features.

Cerebellar lesions pose diagnostic dilemmas when their radiological appearance and clinical course do not align clearly with common pathologies. We describe a case involving a slowly progressive lesion suspicious for CNS lymphoma.

Age: 63 years Sex: Male Medical History: Hypertension, episodic alcohol and tobacco use, cerebellar lesion under follow-up since 2023 Previous Surgeries: Tibial fracture fixation, tonsillectomy, shoulder tumor resection, two prior brain biopsies in 2024

Symptoms: The patient presented with progressive gait instability, dysmetria in the left hemibody, and sensory claudication in the left upper limb. He denied trauma, headache, or seizures.

Neurological Examination: Glasgow Coma Score 15. Left third cranial nerve paresis. No facial palsy or aphasia. Motor strength preserved in all four limbs. Sensory ataxia in the left hemibody.

Laboratory: Elevated white blood cells (13.38 ×10³/µL), neutrophils (8.9 ×10³/µL), and CRP (1.08 mg/dL). Mild hypokalemia (3.4 mmol/L).

MRI

Progressive left cerebellar lesion with contrast enhancement, causing mass effect and compression of the fourth ventricle. Extension to the brainstem. Postoperative CT (02/05/2025): Post-surgical changes without acute complications. Lesion remained hypodense, with cystic areas. No significant change from the previous scan. Midline preserved.

Surgical Procedure: Open cerebellar biopsy with neuronavigation and 5-ALA performed on May 2, 2025. No complications reported.

Medications at Discharge: - Continuation of antihypertensive regimen - Dexamethasone taper starting at 4 mg every 8 hours - Omeprazole 20 mg daily - Paracetamol 1 g every 8 hours if needed - Metamizole 575 mg every 8 hours if pain persists - Enoxaparin 40 mg subcutaneously once daily for 10 days

The patient was discharged in good general condition. He was afebrile, hemodynamically stable, with improved gait and reduced dysmetria following steroid reintroduction. The surgical wound was clean and healing well. Postoperative CT showed no signs of acute complications.

A follow-up visit is scheduled for May 19, 2025, to discuss pathology results. Telephone contact will be made earlier if results become available beforehand.

This case highlights the diagnostic difficulty posed by cerebellar lesions of unknown etiology. The absence of conclusive histology after two biopsies complicated management. Imaging findings and corticosteroid responsiveness raised the suspicion of primary CNS lymphoma. The final diagnosis is pending histological confirmation from the third biopsy.

Cerebellar lesions with inconclusive biopsy results require ongoing multidisciplinary evaluation. This case underscores the importance of clinical judgment, radiologic correlation, and repeated diagnostic efforts in neuro-oncology.