A Diabetic Man With Acute Onset of Pain and Swelling in the Thigh

A 48-year-old insulin-dependent diabetic man presented with a 2-week history of pain and swelling in his right thigh muscle of acute onset.

Past medical history was negative. He had mild renal insufficiency with an elevated creatinine at 2.2 mg/dL (normal, 0.6–1.2 mg/dL).

Family history was not contributory.

Physical examination revealed marked edema, induration, and tenderness in the right thigh. There was evidence of diabetic retinopathy, but the cranial nerves were otherwise normal. Strength was normal, and reflexes were absent in the legs. He had a glove/stocking sensory deficit to all modalities. The remainder of the examination was unremarkable.

Blood sugar was 180 mg/dL (normal, <110 mg/dL). Glycosylated hemoglobin was 9% (normal, <6%); white blood cell count was 14,000 mm ³ with normal differential. Electrolytes were normal. Blood urea nitrogen was 60 mg/dL with a creatinine of 2.4 mg/24 hours. Erythrocyte sedimentation rate was 110 mm/h and serum creatine kinase was 400 IU/L (normal, 55–170 IU/L).

What is the Most Likely Diagnosis?

The focal swelling in the leg in a patient with diabetes raises the possibilities of abscess, hematoma, venous thrombosis, fasciitis, osteomyelitis, tumor, and muscle infarct.

What Would One Do Next?

An MRI was done and was consistent with an infarction, rather than an abscess, as there was marked edema of the vastus medialis muscle ( Fig. 60-1 ).

A muscle biopsy of this area revealed marked necrosis with phagocytosis, hemorrhage, and edema ( Fig. 60-2 ).

He recovered slowly over 1 month with only symptomatic treatment.

Discussion

This man presented with pain and swelling of the thigh. An MRI of the area is useful in ruling out other conditions of similar presentation. MRI in this patient showed edema with increased signal in T2-weighted images. This presentation and the muscle biopsy showing necrosis, edema, and hemorrhage are consistent with the diagnosis of a muscle infarct.

Muscle infarctions or diabetic myonecrosis has been reported in over 100 cases, usually presenting in diabetics of various ages. Both types of diabetes have been implicated, and patients also have evidence of other organ involvement by the disease.

The clinical presentation, as in this case, consists of an acute onset of pain with tenderness, and a palpable mass with induration of surrounding tissue. The pain is present at rest and is exacerbated by movements. Strength is usually preserved.

The most commonly involved muscles are the vastus lateralis, thigh adductors, and biceps femoris.

The cause of diabetic muscle infarcts is unclear, although the pathogenesis is believed to be a thromboembolic event. This, however, has not been clearly demonstrated. Most likely, an initial ischemic event results in tissue swelling and muscle edema; this associates with increased pressure within the fascia and leads to further impairment of blood flow, resulting in infarct and necrosis.

The treatment includes tight glycemic control, bed rest, physical therapy, and analgesics. Some perform surgery to remove the infarcted tissue, but the prognosis is no better than it is with medical treatment. The symptoms usually disappear after weeks to months ; relapses occur, but the overall prognosis is benign. These patients, however, have an increased risk of death from vascular causes, such as myocardial infarction.

Summary

A diabetic man developed an acute onset of thigh swelling and pain. On MRI there was a T2-increased signal and gadolinium enhancement. The muscle biopsy showed necrosis, edema, and hemorrhage. He was diagnosed as having a diabetic muscle infarct.

Important Points

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Unilateral leg swelling in a diabetic should suggest a muscle infarct; other possibilities include abscess, hematoma, osteomyelitis, venous thrombosis, and tumors.
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Diabetic muscle infarcts present as a painful mass, usually in the thigh, with edema and pain.
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The diagnosis is confirmed by MRI that shows the mass with high signal intensity in T2-weighted images and gadolinium enhancement. The test rules out other conditions such as an abscess or tumors.
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Biopsies of muscle infarcts show necrosis, hemorrhage, and edema.
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The etiology of diabetic infarcts is unclear but is thought to be caused by an initial ischemic event with edema and increased ischemia from fascial compression.
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Management is usually conservative.