Thirty-year-old woman with leg pain.

Thirty-year-old woman with leg pain.

Thirty-year-old woman with leg pain.

Thirty-year-old woman with leg pain.

Findings:

CT right lower extremity: There is subcutaneous edema seen throughout the right thigh extending to the lower leg. Edema is visualized within the musculature of the thigh, predominantly involving the vastus medialis. A suprapatellar joint effusion is also noted.

MRI right lower extremity: Extensive soft tissue edema is seen throughout the right lower extremity extending from the right hip to the right knee most prominent anteromedially involving the following muscles: vastus medialis, vastus intermedius, and the biceps femoris. There is also fluid in subcutaneous tissue and intermuscular fascia

Differential Diagnosis:

• Diabetic myonecrosis
• Necrotizing fasciitis
• Inflammatory/infectious/immune myositis

Diagnosis:  Diabetic myonecrosis

Pathologic correlation: Portions of skeletal muscle and fibrovascular tissue with active inflammation, necrosis and evidence of recent hemorrhage.

Thirty-year-old woman with leg pain.

Discussion

Diabetic myonecrosis is a rare and under recognized myopathy which is a complication of poorly controlled diabetes. It should be suspected in patients with type 2 diabetes who present with thigh pain or knee effusions. Most patients present with acute pain and swelling, often localized to the thigh. It is frequently bilateral. The cause of diabetic myonecrosis is believed to be related to hypoxia reperfusion injury, atherosclerotic occlusion, or vasculitis wit. .

The differential diagnosis of diabetic myonecrosis includes: necrotizing fasciitis, inflammatory, infectious, immune myositis, and pyomositis. Severe pain is very characteristic of diabetic muscle infarction and may not be seen with necrotizing fasciitis or pyomyositis.  This entity should always be considered in the differential diagnosis of acute muscle pain in a patient with diabetes.

Although characteristic MRI and clinical findings may be sufficient for diagnosing diabetic myonecrosis, tissue biopsy remains the gold standard for diagnosis. Histopathologic examination may reveal differing areas of muscle infarction with foci of hemorrhage, fatty infiltration, and zonal necrosis. Biopsy cultures for organisms are negative.

Treatment includes conservative care with analgesics and anti-inflammatory agents. Symptoms gradually resolve in weeks to months. However, once diabetic myonecrosis develops, the likelihood of recurrence in the same muscle exceeds 50%.  Long term prognosis of patients with diabetic myonecrosis is poor, since this is a marker for significant vascular complications of diabetes mellitus. Early diagnosis of diabetic myonecrosis is crucial. It can limit unnecessary and potentially harmful diagnostic interventions, focus attention on tighter control of hyperglycemia and management of other atherosclerotic risk factors, and promote timely physical therapy to reduce long-term impairment.

Radiology: CT shows muscle edema with preserved tissue planes.  MRI shows increased signal on T2 weighted images within areas of muscle edema. Post contrast T1W images show areas of rim enhancement

Key Points:

• Diabetic myonecrosis is a rare complication of diabetes which most commonly occurs in the thigh and is frequently bilateral. Although the exact cause is not known, possible etiologies include atheroembolic vascular compromise that leads to ischemia, followed by fibrinolysis and reperfusion injury.
• Diagnosis is usually clinical but is highly supported by characteristic MRI findings. The gold standard of diagnosis remains muscle biopsy.
• Treatment is symptomatic and should focus on rapid restoration of glycemic control.
• Diabetic myonecrosis has a high recurrence rate, and patients have a significant mortality rate secondary to vascular complications.

References:

1. Trujillo-Santos AJ 2003 Diabetic muscle infarction. Diabetes Care 26:211–215

2. Habib G, Nashashibi M, Walid S 2003 Diabetic muscular infarction: emphasis

on pathogenesis. Clin Rheumatol 22:450–451

3.Umpierrez GE, Stiles RG, Kleinbart J, Krendel DA, Watts NB. Diabetic muscle infarction. Am J Med. 1996;101:245-50

4. Kapur S. and RJ McKendry. Treatment and outcomes of diabetic muscle infarction. J Clin Rheumatol. 2005 Feb; 11:8-12.

Thirty-year-old woman with leg pain.