A Rare Case of Tuberculosis as a Cause of Lytic Lesion of Talus Without Adjacent Bone Involvement in a Four-Year-Old Child.

Extra-pulmonary tuberculosis still remains an important differential diagnosis for chronic musculoskeletal ailments in developing countries like India and may involve any part of the body without characteristic systemic features. We are presenting a rare case of a four-year-old female child, who came to our tertiary-care hospital with chief complaints of pain in the left foot along with a gradually increasing swelling over the dorsum of the foot for the past five months. There was no history of trauma or constitutional symptoms. The serum inflammatory markers were found raised, and X-ray and magnetic resonance imaging revealed an isolated lytic lesion in the talus bone. Debridement, as well as curettage of the lesion, was done, both as a diagnostic and therapeutic procedure. A caseous cheesy material was evacuated and sent for microbiological and histopathological evaluation, which revealed the presence of acid-fast bacilli and granulomatous lesion confirming the diagnosis of tuberculosis. The patient was started with anti-tubercular chemotherapy, which continued for a total duration of 14 months, along with foot and ankle immobilization in a below-knee cast for three months. After completion of therapy, there was complete resolution of the lytic lesion on x-ray, with full symptom relief, and a full range of movement of the ankle was obtained. In cases with longstanding pain and swelling of the foot, with or without associated systemic symptoms, tuberculosis should be considered as a strong differential diagnosis even in young children, especially in developing countries. Diagnostic and therapeutic curettage along with anti-tubercular chemotherapy can result in a good functional outcome in such patients.