Osteomyelitis Caused by Mycobacterium Tuberculosis in Atypical Sites: A Case Report

Tuberculosis (TB) is an infectious and contagious disease caused by Mycobacterium tuberculosis, primarily affecting the lungs. Extrapulmonary involvement represents around 10% of cases, and among these, musculoskeletal involvement ‒ especially of the spine, hip joint, and knees ‒ is not rare. Although these sites are most frequently affected, other bony structures such as the sternum, clavicle, and costovertebral region may be involved, making diagnosis challenging and often delayed. A 54-year-old man sought hospital care due to the appearance five months earlier of bilateral infraclavicular nodules with spontaneous drainage, edema, and significant pain in the right foot, associated with unintentional weight loss of 6 kg, low-grade evening fever, night sweats, and productive cough with hyaline sputum. During investigation, the patient reported a history of pulmonary TB treated in April/May 2024. During hospitalization, a soft-tissue ultrasound showed a collection in the right lower limb. In aspirative puncture of the abscess, 20 mL of purulent fluid was collected; microbiological analysis showed smear positive 3 crosses/4 and TB molecular rapid test detected and rifampicin-sensitive. Chest CT also showed sternoclavicular and costovertebral bone destruction, reinforcing the hypothesis of systemic granulomatous infection compatible with extrapulmonary bone TB. CT of the right foot revealed large joint effusions, erosions, bone fractures, and soft-tissue edema, compatible with an infectious process. Treatment was initiated with rifampicin, isoniazid, pyrazinamide, and ethambutol (RHZE), with an estimated duration of 12 months (2 months RHZE and 10 months RH), requiring new decompressive punctures in the right foot and ankle due to persistence and worsening of inflammatory signs. After hospital discharge, he remains in outpatient follow-up with Infectious Diseases, as well as Vascular Surgery and Orthopedics, with possible right lower limb amputation and a new surgical approach to the clavicle. The reported case, although not a rare condition, represents a clinical challenge. Careful multidisciplinary management ‒ from proper sample collection, to treatment and continuous surveillance ‒ are fundamental pillars for early diagnosis and effective therapeutic management.