A 45-year-old woman presents with progressive headache, left-sided hemiparesis, and papilloedema. MRI brain shows a ring-enhancing lesion with surrounding oedema in the right parietal lobe. CSF shows elevated protein, lymphocytosis, and low glucose. No known primary malignancy. HIV negative. The lesion is single. Which diagnosis most requires immediate empirical treatment while awaiting definitive confirmation?

• A Glioblastoma multiforme — start dexamethasone + temozolomide + RT
• B Cerebral metastasis from unknown primary — CT-PET for staging before treatment
• C Primary CNS lymphoma — start high-dose methotrexate-based chemotherapy empirically
• D Cerebral abscess — empirical antibiotics (ceftriaxone + metronidazole ± vancomycin) + dexamethasone while awaiting aspiration culture ✓

Explanation

The combination of ring-enhancing brain lesion with CSF pleocytosis (lymphocytosis) and low glucose (bacterial/fungal infection pattern) alongside progressive mass effect (papilloedema) is most consistent with cerebral abscess. GBM and metastases typically have normal-to-high CSF glucose without significant pleocytosis. Primary CNS lymphoma has lymphocytic pleocytosis but glucose is usually normal and it occurs in immunocompromised patients. Cerebral abscess requires urgent empirical IV antibiotics (ceftriaxone + metronidazole targeting streptococci and anaerobes; vancomycin if MRSA suspected) plus CT-guided stereotactic aspiration for culture/drainage. Dexamethasone reduces oedema but should be used cautiously as it may worsen abscess by reducing antibiotic penetration. Definitive management requires neurosurgical drainage.

Reference: Bailey & Love's Short Practice of Surgery, 27th ed.

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Written and medically reviewed by the StethoPrep medical team.