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A 9 year old male presented with a two year history of a painless mass overlying the fourth finger of the right hand. Of note was that he had been started on antituberculous treatment two weeks prior to presentation. A chest radiograph showed right upper lobe airspace disease with associated hilar adenopathy consistent with pulmonary tuberculosis (TB); a radiograph of the right hand (fig 1) showed a cystic, expansile lesion of the distal portion of the proximal phalanx of the right ring finger. The margins were well defined and there were internal septations and associated cortical sclerosis. There was cortical destruction but no periosteal reaction. A large soft tissue mass surrounded the bone lesion. This was diagnosed as tuberculous dactylitis based on the imaging findings and the coexisting diagnosis of pulmonary TB.
Bone and joint TB occurs in 1–5% children who have untreated initial pulmonary TB.1 Spread to the skeletal system occurs during the initial infection via the lymphohaematogenous route.1 The skeletal infection often becomes symptomatic within 1–3 years after the initial infection.1 Eighty five per cent of patients with TB dactylitis are younger than 6 years of age and its incidence among children with TB is reported to be 0.65–6.9%.2 The bones of the hands are more frequently affected than bones of the feet, with the proximal phalanx of the index and middle fingers the commonest sites for infection.2 The condition usually presents as a painless swelling of a digit of a few months duration. The radiographic features of cystic expansion of the short tubular bones has led to the name of “spina ventosa” being given to TB dactylitis of the short bones of the hand.2, 3 Periosteal reactions and sequestra are not common features but may occur. Sclerosis may be seen in long standing cases.3