Bacille Calmette-Guérin (BCG) osteomyelitis: a rare complication of BCG vaccination

The BCG vaccine is considered a safe and efficacious vaccine in the prevention of severe forms of tuberculosis. BCG osteomyelitis is a rare complication of the BCG vaccine that occurs in vaccinated young children. We report a case of BCG osteomyelitis in a male toddler, presenting with painful left wrist swelling without preceding fever or systemic symptoms. Radiographic evidence of osteomyelitis in the left wrist was observed. Initial treatment with conventional antibiotics for acute haematogenous osteomyelitis showed no improvement. The diagnosis of <i>Mycobacterium bovis</i> BCG osteomyelitis was confirmed via tissue samples for histopathological examination and mycobacterial cultures. The patient responded well to treatment with oral antituberculous therapy. This case highlights the importance of considering BCG osteomyelitis in the differential diagnosis of unexplained joint swelling in BCG-vaccinated young children.