Right arm pyomyositis and necrotizing fasciitis complicated with subcutaneous emphysema and pneumomediastinum in a patient with diabetes mellitus and iatrogenic Cushing syndrome.

We report a case of subcutaneous emphysema and pneumomediastinum secondary to pyomyositis and necrotizing fasciitis over the right arm of a woman with underlying diabetes mellitus and iatrogenic Cushing syndrome. Gas produced by the culprit pathogen extensively dissected the subcutaneous fat and fascia of the patient's right arm and distantly spread to her face, neck, back, and thoracic wall and penetrated the soft tissue cephalically bordering her sternum, resulting in pneumomediastinum. The patient improved-with antimicrobial therapy and localized debridement and fasciotomy over her right arm.