The applicable age for BCG vaccination was lowered from less than 4 years old to 6 months old in April 2005. Since then, the incidence of BCG osteomyelitis has increased, and 2-9 cases per year have been reported since 2006. A previously healthy 16-month-old girl was taken to a local clinic because she had become unable to raise her right arm. This did not change for 1 month, so she was brought to the outpatient clinic of our hospital. MRI suggested a bone tumor at the proximal metaphysis of the right humerus, and curettage and biopsy of the bone were performed. The pathological analysis of the biopsy specimen revealed the formation of granuloma, but polymerase chain reaction analysis showed that the curetted tissue was negative for acid-fast bacteria. However, 5 weeks later, M. tuberculosis complex was detected on a culture test for acid-fast bacteria. Gene analysis revealed M. bovis BCG (Tokyo 172). Finally, a diagnosis of BCG osteomyelitis was made. During medication-free follow-up until definitive diagnosis, osteomyelitis recurred. Additional surgery was conducted 4 months after the initial surgery and the administration of anti-tubercular agents were started.
Our findings suggest that it is difficult to cure BCG osteomyelitis only with bone curettage even if there are no clinical symptoms. When infection with acid-fast bacteria is suspected based on pathological results of a biopsy specimen, the administration of anti-tubercular agents should be started. Subsequently, de-escalation should be considered after definitive diagnosis of BCG osteomyelitis.