A 49-year-old man with the acquired immunodeficiency syndrome and a tibial lesion

A 49-year-old male HIV patient was admitted to a hospital with a three-month history of pain in his left knee. He had fractured his left shin bone 12 years earlier. An X-ray of his left leg and a bone scan both showed an abnormality in his left leg close to the knee. A bone biopsy showed that he had a bone infection called osteomyelitis and the organism responsible was Mycobacterium avium complex. This bacterium is a common cause of opportunistic infection in AIDS patients.