Paradoxical evolution of a cerebellar tuberculosis abscess after surgical drainage and antibiotic therapy

BACKGROUND: Involvement of the central nervous system (CNS) by a tuberculosis abscess is a rare form of extra-pulmonary tuberculosis. With proper treatment, the abscess most commonly follows a pattern of continued reduction in size. CASE DESCRIPTION: A 71-year-old male with a past medical history of kidney transplant on immunosuppressive therapy, presented to the hospital with a 1-day history of headache. On physical examination, the patient had no focal neurological symptoms. Initial laboratory reports were unremarkable. Contrast enhanced magnetic resonance imaging (MRI) was performed, which showed a ring enhancing mass and perilesional edema in the left cerebellar hemisphere. The patient underwent a left posterior fossa biopsy and drainage. The lesion was encapsulated with a purulent center. Cultures revealed pan-sensitive mycobacterium tuberculosis and the patient was started on rifampicin, isoniazid, pyrazinamide, ethambutol, and B6. The patient was monitored carefully and brain MRIs were obtained at 1, 4, 9, 11, and 14 months. It was noted that the tuberculosis abscess had grown in size from month 4 to month 9 of treatment. Since the patient's neurologic examination and symptoms were stable at that time, the drug regimen was not changed. The 14-month follow up MRI showed that the abscess had nearly resolved. CONCLUSION: Rarely, the pattern of CNS tuberculosis abscess evolution may include growth, even with proper treatment. This pattern does not necessarily signify treatment failure, as our abscess resolved without change in treatment. Given the possibility of asymptomatic abscess enlargement, close clinical and imaging follow up are crucial in management of these cases.