Sacral Tuberculosis.

An otherwise healthy 29-year-old Indonesian man presented with a 6-month history of low back pain and right buttock swelling, with radiating pain into the right leg. The pertinent laboratory results were as follows: WBC 12,000/ μL, C-reactive protein 9.08 mg/dL, a normal urinalysis, and a negative human immunodeficiency virus test. Computed tomography (CT) revealed an expansile low density mass involving the sacrum and right ilium, extending into the bilateral buttock (Picture 1). The mass was lobulated and cystic on magnetic resonance imaging (Picture 2). A biopsy revealed caseating granulomas, and a polymerase chain reaction (PCR) analysis, as well as a biopsy culture for Mycobacterium tuberculosis, was positive. Chest CT (Picture 3) showed a typical pattern compatible with tuberculosis, and a