Chronic Inflammation of the Tibiotalar Joint with a Lateral Malleolar Fistula: A Rare Presentation of Tuberculosis

Skeletal tuberculosis accounts for 1-3% of all tuberculosis cases and 10-11% of extra- pulmonary tuberculosis. Ankle and foot involvement presents in less than 5% of all skeletal tuberculosis. Primary tuberculous pyomyositis, bursitis, and tenosynovitis are rare and account for about 1% of skeletal tuberculosis. Joint involvement of tuberculosis most commonly manifests as a mono-arthritis of weight-bearing joints in the hip or the knee. Trauma has been associated with tuberculosis in 30-50% of cases. As the elderly population is growing, the rate of tuberculosis in particular extra-pulmonary and atypical forms of disease has increased among older adults. We report a 79-year-old woman complaining of chronic ankle pain, swelling and a lateral malleolar fistula. Her past medical and family histories revealed no previous tuberculosis. An ankle strain of her left ankle after slipping had occurred prior to her problem. There was no evidence of concomitant tuberculosis at other sites. The PPD test was negative. The combination of indolent onset of symptoms and compatible MRI findings strongly suggested the diagnosis. Ankle synovial biopsy showed necrotising granulomatous inflammation and PCR test detected mycobacterium tuberculosis genome in the synovial tissue. A careful suspicion of the diagnosis of tuberculosis is paramount in patients with chronic mono-articular arthritis, even in absence of a positive tuberculin test or abnormalities on chest radiograph.