Background <p>Extrapulmonary tuberculosis occurs in 15% to 20% of immunocompetent patients with tuberculosis and in 50% of immunocompromised patients. Its prevalence varies based on local disease rates. Tuberculosis remains a significant health concern in tropical countries. Chest wall tuberculosis is rarely documented in the literature. Skeletal involvement of tuberculosis is a challenging diagnosis that may be mistaken for tumors. Confirming the diagnosis generally requires microbiological or histological evidence, and treatment involves surgical debridement and chest wall reconstruction, followed by long-term antimicrobial therapy.</p> Case presentation <p>Our report describes a 34-year-old healthcare worker with a painless mass in the right sternocostal joint. She worked in a clinical laboratory. The X-ray showed a diffuse image in the first and second costal arches involving the sternum. A biopsy report indicated caseous necrosis and the absence of epithelioid cells. Surgeons performed an extensive resection of the infected bone and a chest wall reconstruction. The patient was treated afterward with combined anti-tuberculosis chemotherapy, and the response has been favorable so far.</p> Conclusions <p>Extrapulmonary manifestations of tuberculosis are rare and need a high index of suspicion and microbiological confirmation to avoid misdiagnosis as neoplasms.</p> Clinical trial number <p>Not applicable.</p>