We report two cases of suspected bone infarction diagnosed by MRI. In the first case clinical findings were not significant, but serological data revealed an inflammatory reaction with the white blood cell count of 6, 800/ml, C reactive protein level of 3.2mg/dl, and erythrocyte sedimentation rate of 49.8mm/hr. In the second case, no other abnormality was observed besides calcaneal pain.
Both cases were suspected of bone infarction on MRI. However the first case was pathologically diagnosed as osteomyelitis, and Streptococcus anginosus was cultured. The second cese was pathologically diagnosed as bone infarction.
Although Streptococcus anginosus rarely causes osteomyelitis, it occasionally does in immuno-suppressed patients. Absence of clinical findings is characteristic of osteomyelitis due to this organism and its MRI findings are similar to bone infarction. Therefor careful investigations are necessary for diagnosing immuno-suppressive diseases in cases of suspected bone infarction on MRI.