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Diabetic muscle infarction (DMI), or spontaneous diabetic myonecrosis is a rare complication of diabetis mellitus (DM). Though its pathogenesis is still not clear, various mechanisms such as atherosclerosis, vasculitic arteriolopathy, diabetic microangiopathy, ischemic-reperfusion injury, or hypercoagulability are suggested. Typical presentation of DMI is acute, atraumatic, unilateral (sometimes, bilateral), painful swelling of thigh. As it usually occurs in long-established, poorly controlled diabetic patients, it often accompanies other microvascular complications of DM when occurs. The diagnosis of DMI is made by aggregating clinical patterns, laboratory tests and imaging studies such as MRI, and even biopsy can be performed if necessary. Because there is no specific pathognomonic finding of DMI, misdiagnosis is common. Since we have diagnosed four patients with DMI and treated them, we report a case series of four patients with DMI.To summarize the clinical findings of our 4 patients (5 Episodes including recurrence of one patient), the affected area was thigh in all patients, especially anterior thigh. All patient present pain as the first symptom, and swelling was also accompanied by all patients except one. All patients had type 2 DM (T2DM), and an average duration of DM was 14.2 years. An average HbA1c was 9.5%, and all patients had more than two microvascular complications of DM at presentation.Erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) were elevated in all patients, although there was a difference in degree. Leukocytosis was observed in only one in five episodes, suggesting that DMI may be more suspicious than infection when ESR and CRP were elevated without leukocytosis. In terms of muscle enzyme, Creatine kinase (CK) or lactate dehydrogenase (LD) was elevated in all patients, but the increase was mild with up to 5 times higher than the upper limit of normal ranges. This could be a differential point from inflammatory myositis, which can show a rise of up to 50 times of the upper limit. In our study, common MRI findings were loss of the intermuscular septum and iso- or hypointensity in T1-weighted images and hyperintensity of muscle with subcutaneous edema and subfascial fluid in T2-weighted images. In addition, diffuse heterogeneous enhancement with low-signal, non-enhancing necrosis foci in contrast-enhanced images were noted. Biopsy is usually performed when not diagnosed by other tests. But in our cases, diagnostic value of biopsy was low. Early recognition of DMI is vital to initiation of prompt treatment. However, because physicians do not familiar with this diseases entity, it is often misdiagnosed and unnecessary treatment is given. Though all of our patients had no fever or had a brief fever during the hospital visit, all of them had antibiotics and ceased at last. Despite relatively typical clinical patterns of DMI in our cases, diagnosis was delayed in all. |
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Table 1. Clinical findings in four patients with diabetic muscle infarction
FIGURE 1. MRI images of case 1. (A) Axial T1-weighted image of left distal thigh shows diffuse subcutaneous edema, poor delineation of intermuscular septums, and focal hypointense lesions within vastus medialis and vastus intermedius muscle (asterisks). (B) Axial T2-weighted image shows diffuse hyperintensity within vastus medialis, vastus intermedius, rectus femoris ,and adductor muscles. Focal hypointense lesions within vastus medialis and vastus intermedius muscle is also seen (asterisks). (C) Axial fat-suppressed contrast-enhanced T1-weighted image shows similar pattern of elevated signal within the affected muscles similar to the distribution seen on T2-weighted image. Focal hypointense lesions seen on T1- and T2-weighted images were not enhanced (asterisks).
FIGURE 2. MRI images of case 2. (A) Axial T1-weighted image of left proximal thigh shows diffuse subcutaneous edema, and marked swelling of vastus medialis muscle (asterisk). (B) Axial fat-suppressed T2-weighted image shows diffuse hyperintensity within vastus medialis muscle. (C) Axial contrast-enhanced T1-weighted image shows diffuse heterogenous enhancement of vastus medialis muscle, with focal non-enhancing area within the muscle (asterisks).
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