Abstract
A 37-year-old woman with uncontrolled type 1 diabetes mellitus and end-stage renal disease presented to our hospital with 10 days of severe left thigh pain. Physical examination revealed warmth, swelling, and tenderness of the left anterior and medial thigh. Workup revealed a mildly elevated creatinine kinase. Magnetic resonance imaging without contrast revealed diffuse extensive soft tissue edema and a heterogeneous, tubular fluid collection within the adductor magnus. Needle aspiration revealed hematoma and myonecrosis. Cultures and cytology were negative. A diagnosis of diabetic myonecrosis was made. Myonecrosis is a rare complication of diabetes, and the gold standard for diagnosis is tissue biopsy. However, magnetic resonance imaging may be sensitive and specific for diagnosis and prevent morbidity.
Keywords: Biopsy; diabetes, uncontrolled; magnetic resonance imaging; myonecrosis
Diabetic myonecrosis, also known as diabetic muscle infarction, is a rare complication of uncontrolled diabetes mellitus (DM).1 The classic features are the acute onset of swelling, discomfort, and soreness over an affected deep muscle group that progressively worsens. The anterior thigh is the most affected area, followed by the posterior thighs and calves.2 Nowadays, diabetic myonecrosis is infrequently seen, given the breadth of diabetes medications available. Herein, we present a case of diabetic myonecrosis presenting with thigh pain and swelling and discuss the role of imaging in diagnosis to avoid unnecessary biopsy.
CASE PRESENTATION
A 37-year-old woman with uncontrolled type 1 DM presented with hemoglobin A1c of 14.5%. Her DM was complicated by episodes of diabetic ketoacidosis and end-stage renal disease (hemodialysis on Monday, Wednesday, and Friday; only access in left upper extremity). She presented to our hospital with 10 days of severe left thigh pain that was constant, aching, and occasionally stabbing in nature without radiation. She denied overlying skin changes and constitutional symptoms. Prior to admission, she was prescribed cephalexin, clindamycin, and pain medications for presumed cellulitis at an outside hospital.
She reported no trauma, falls, or inciting events. Physical examination revealed atraumatic warmth, swelling, and tenderness of the left anterior and medial thigh. The complete blood count was within normal limits. The serum creatinine was 4.27 mg/dL; potassium, 5.1 mmol/L; blood urea nitrogen, 49 mg/dL; and creatinine kinase, 277 U/L. Arterial and venous Doppler ultrasounds to assess the arteriovenous circulation of the left anterior thigh were negative for vascular occlusions. Thereafter, magnetic resonance imaging (MRI) without contrast was obtained. This imaging modality revealed diffuse extensive soft tissue edema and a heterogeneous, tubular 11.7 cm fluid collection within the adductor magnus (Figure 1).
Figure 1.
MRI of the left thigh revealing diffuse extensive soft tissue edema and a heterogeneous and tubular 11.7 cm fluid collection within the adductor magnus, both of which also likely reflect diabetic myonecrosis.
Considering this, interventional radiology was consulted for needle biopsy and sampling of the tissue. Needle aspiration of the fluid collection revealed hematoma and myonecrosis. Cultures and cytology were negative. The clinical presentation, MRI findings, and biopsy confirmed a diagnosis of diabetic myonecrosis.
DISCUSSION
Diabetic myonecrosis is an uncommon and underdiagnosed sequela of uncontrolled DM. It is one of the many microvascular and macrovascular complications that plague patients with DM, especially those with poor disease control. Other diabetes-related vascular insults include diabetic nephropathy, neuropathy, and retinopathy.2
One suggested mechanism is an inflammatory cascade activation process due to the microvascular endothelial damage that occurs, causing tissue ischemia.3 Another suggested mechanism is a hypercoagulable state causing endothelial damage.4 Antiphospholipid antibodies have also been proposed in this disease, which may also result in vascular occlusion phenomenon.5
Diabetic myonecrosis is more commonly witnessed in middle-aged individuals, with a female predominance. Patients with type 1 DM are typically younger at diagnosis than those with type 2 DM.2 Common symptoms are subacute focal pain and swelling without precipitating fever or trauma. Some clinicians have reported that examinations may reveal a firm, tumor-like mass.4 The most common sites involved are the lower extremities, particularly the anterior thigh. Involvement of the anterior aspect of the lower legs or upper extremities is peculiar and should prompt consideration of an alternative diagnosis, such as erythema nodosum. Involvement is typically a unilateral limb.2,6
The workup entails the collection of routine laboratory investigations, even though these are typically nonspecific. However, elevated inflammatory markers may be present along with leukocytosis and elevated creatinine kinase levels.7 Elevated hemoglobin A1c is a hallmark of uncontrolled DM and is seen in this presentation2,8; it would be very unusual to witness diabetic myonecrosis in a patient with mildly elevated hemoglobin A1c.
MRI is a sensitive and specific modality for the diagnosis of diabetic myonecrosis. Classical radiological findings are muscle edema with a hyperintense T2 signal along with subcutaneous and interfacial edema. Furthermore, some radiologists report rim enhancement surrounding the areas of necrosis within the ischemic muscle.8,9
The diagnosis is one of exclusion. The differential diagnosis includes inflammatory or drug-induced myopathy, deep venous thrombosis, abscess, necrotizing fasciitis, and pyomyositis.10 Biopsy can provide histopathologic confirmation but may be unnecessary in patients with suggestive clinical and imaging features without findings of an alternative etiology.6,7 Additionally, a biopsy can lead to prolonged pain and poor wound healing.
Treatment for diabetic myonecrosis is symptomatic management with nonsteroidal antiinflammatory medications/narcotics, physical therapy, activity as tolerated, and early initiation of low-dose aspirin, the cornerstone of management. The short-term prognosis is good, with recovery occurring in a few weeks, but recurrences are frequent (∼40%).7
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