Diabetic myonecrosis: likely an underrecognized entity.

Diabetic myonecrosis is a rare complication of long-standing diabetes mellitus that presents as acute onset of swelling and pain of the affected muscles. The differential diagnosis includes cellulitis/pyomyositis, necrotizing fasciitis, neoplasm, and deep venous thrombosis (DVT). Missed diagnoses can lead to unnecessary invasive diagnostic procedures and inappropriate treatment. The diagnosis is established by the clinical presentation and findings on magnetic resonance imaging (MRI) scan. A 30-year-old African-American man presented with a painful mass affecting the medial aspect of the right thigh for several months. Initial laboratory studies showed white blood cell count of 8800 cells/mm(3), D-dimer value of 0.55 µg/mL, HgBA1c level of 15.1%, glucose level of 352 mg/dL, erythrocyte sedimentation rate of 22 mm/h, and C-reactive protein level of 222 mg/L. An MRI scan was obtained, and diabetic myonecrosis was diagnosed and treated. One year later, the patient had similar symptoms of pain in the contralateral thigh. Repeat workup and MRI scan were obtained. The MRI abnormalities originally seen in the right thigh 1 year earlier were present in the left thigh, with complete resolution of the abnormalities seen in the right thigh. Treatment with bed rest and analgesics resulted in symptom resolution. Patients with diabetic myonecrosis typically have no fever, normal white blood cell count, mildly increased erythrocyte sedimentation rate, and elevated C-reactive protein level in 50% of cases. They lack the radiologic signs of fascial enhancement or well-defined, rim-enhancing collections that are seen in necrotizing fasciitis and pyomyositis/abscess. The onset of severe pain and the lack of mass effect on imaging differentiate diabetic myonecrosis from tumor-like conditions such as vascular malformations or soft tissue tumors. Normal D-dimer levels and ultrasound Doppler examination of the extremity help to rule out DVT. The typical MRI scan findings and clinical presentation can lead to the diagnosis of diabetic myonecrosis, allowing the physician to avoid invasive tests, such as muscle biopsy, and to reassure patients that this condition is self-limiting with appropriate treatment.