Rare multifocal emphysematous osteomyelitis as a complication of metastatic rectal cancer

Emphysematous osteomyelitis (EOM) is a rare and severe subtype of osteomyelitis where infection potentiates free air into surrounding bone. Existing literature is limited, but diabetes mellitus and malignancy are described as major risk factors. We report a patient that presented with multiple perianal abscesses and was diagnosed with an advanced rectal adenocarcinoma. He was treated with abscess drainage, antibiotics, and diverting colostomy. Several weeks later he was readmitted in septic shock and was found to have extensive areas of intraosseous gas on CT imaging involving the pelvis, thoracic and lumbar spine, left femur, and several ribs bilaterally. Biopsy culture grew <i>Clostridium novyi</i>, a pathogenic obligate anaerobe. The patient was successfully treated with broad-spectrum antibiotics. Only a handful of cases of multifocal EOM exist in current literature. More research is needed to classify the relationship between metastatic cancer and EOM and to identify modifiable risk factors of this complication.