Unmasking the “Great Masquerader:” Tuberculosis of the Foot

Abstract

Abstract Introduction: Osteoarticular tuberculosis (TB) accounts for only 1%–3% of extrapulmonary TB, of which ankle and foot involvement accounts for only 8%–10%. Foot and ankle TB has a varied clinical and radiological presentation and can mimic many conditions. The aim of this study is to throw light on the varied clinical and radiological presentations of this disease. Materials and Methods: We studied 20 patients with suspected osteoarticular TB of the ankle and foot region over 3 years. The patients were evaluated based on clinical presentation, radiology, magnetic resonance imaging (MRI) findings, molecular studies (cartridge-based nucleic acid amplification test [CBNAAT]), biopsy, microbiological staining and culture, erythrocyte sedimentation rate ESR, and C-reactive protein levels. The patients were categorized into subgroups in accordance with their findings. Results: All cases had some form of pain, swelling, tenderness, or inability to bear weight. Twenty-five percent presented with single or multiple draining sinuses at or around the ankle. On X-rays, 30% had unremarkable radiographs, and osteopenia/cavitation of one or more bones was found in 30% of cases. Sequestrum formation was seen in 20% of the cases. No advanced arthritis and collapse were noted. In MRI, all cases had marrow edema of one or more bones. Twenty percent had features of tenosynovitis. CBNAAT was done for all the patients of whom eight turned positive for the pathogen. Discussion: The classical features of skeletal TB may elusive in cases of TB of the foot and ankle. Plain radiographs may not be sensitive in detecting early cases. In MRI studies, the calcaneum and talus were mostly affected. This may indicate toward a hypothesis that the calcaneum/talus may be the primary source of origin in osteoarticular TB of the ankle and foot region. Biopsy remains the gold standard in diagnosing TB. All patients responded well to the medical management. We can conclude with surety that TB of the foot and ankle is primarily a medical condition if prompt and early diagnosis is made.