A 25–year–old Asian Indian male studying in Poland presented with pain, swelling and drainage from the right clavicular area of 15 days duration limiting his activity. Four months ago, he was diagnosed with abscess at the right sternoclavicular joint for which he underwent incision and drainage and was doing fine until the current presentation. He had two episodes of cough with hemoptysis along with 5 lbs weight loss in the last 6 months. He was placed on empiric antibiotic coverage with vancomycin which was changed to cephalexin when culture from the drainage site was positive for methicillin sensitive staphylococcal aureus (S aureus). As clavicular infection with S aureus is rare and usually secondary to a predisposing factor we did a CT scan of chest. It revealed two lytic lesions in the medial right clavicle along with mediastinal and hilar lymphadenopathy. He underwent excision of the sinus tract along with clavicular bone biopsy and the latter was sent for culture studies. The Quantiferon gold was positive and the cultures from bone grew mycobacterium tuberculosis (Tb) and S aureus. The HIV test was non–reactive. He was placed on 9 months of combination therapy, isoniazid, rifampin, pyrazinamide and ethambutol for 2 months, then isoniazid and rifampin for 7 months in view of Tb osteomyelitis.
Osteomyelitis of the clavicle is rare, with an incidence ranging from 0% in a mixed–age population to 7% in children. Any portion of the clavicle can be affected, but the medial half of the clavicle seems to be the preferred site. Osteomyelitis may involve the clavicle either as a primary infection of hematogenous origin or as a secondary infection originating in a contiguous focus. In children, its origin is generally hematogenous, while in adults, clavicular osteomyelitis is more commonly a secondary infection seen in association with predisposing factors such as systemic coccidioidomycosis, IV drug abuse, Tb, mitral valve prosthesis, diabetes, previous lung carcinoma or prior head and neck surgical procedures. S aureus is the predominant causal agent in clavicular infections, and this is valid for all age groups. Tb of the clavicle is a rare infection and can be difficult to diagnose in early stages especially when masked by concomitant S aureus infection. Clinicians should not hesitate to evaluate patients at risk of tuberculous osteomyelitis with imaging techniques such as MRI and CT scans and proceed early to an open synovial biopsy. Delaying the diagnosis leads to progression of the disease and carries the risk of devastating destruction of the affected bone or joint.
Tuberculosis has a chronic and insidious course that could be masked by other bacterial co–infections. A high index of suspicion is required in appropriate clinical setting to prevent further deterioration.