A Case of Uncommon Tuberculosis Infection Involving the Sternoclavicular Joint

BACKGROUND Tuberculosis involving the sternoclavicular joint is a rare manifestation of extrapulmonary tuberculosis. Involvement of the muscular and skeletal system in tuberculosis accounts for approximately 10% of extrapulmonary tuberculosis cases. Of these, only 1% to 2% involve infection of the sternoclavicular joint. The presentation of sternoclavicular joint tuberculosis is often insidious without systemic symptoms. Its diagnosis is very difficult because it mostly occurs with an atypical presentation, therefore requiring a multimodal diagnostic approach. Patients can require a combination of several tests, including imaging, polymerase chain reaction, microbiologic tests, histopathological tests, and acid-fast bacilli smear and culture to generate a reliable diagnosis. CASE REPORT We present a case of a 77-year-old woman originally from Tibet who had lived in India for several years and presented with localized pain and swelling over the left medial clavicle. Chest computed tomography demonstrated a lytic lesion involving the medial aspect of the left clavicle with a soft tissue mass. Biopsy of the soft tissue mass at the left clavicular head revealed granulomatous inflammation, and cultures confirmed the presence of acid-fast bacilli, Mycobacterium tuberculosis. The patient was successfully treated with a 12-month course of anti-tuberculous therapy. CONCLUSIONS Diagnosis of tuberculous involvement of the sternoclavicular joint is usually challenging and requires a multimodal diagnostic approach. A high index of suspicion is important, especially in patients with risk factors for tuberculosis exposure. Early diagnosis, early initiation, and appropriate duration of anti-tuberculous therapy can lead to successful treatment outcomes.