Diabetic Myonecrosis: An Underreported and Frequently Misdiagnosed Complication of Diabetes Mellitus

Diabetic muscle infarction (DMI), also referred as diabetic myonecrosis, is a rare and underdiagnosed complication of longstanding and poorly controlled diabetes mellitus. The usual presentation is sudden onset of pain at the involved muscles associated with swelling and tenderness. The diagnosis may be easily missed if clinical vigil is not high.

Case Description:

A 40-year-old male patient, known case of type 2 diabetes mellitus (T2DM) for 8 years presented with swelling and tenderness of the right thigh for past two weeks. Prior medical history was significant for hypertension and chronic kidney disease. The pain was sharp aching in nature and worsened with weight bearing or movement of affected limb. There was no prior history of trauma or fall. On examination, the right thigh was grossly swollen and tender to palpation. Complete blood count revealed presence of anemia (Hemoglobin 8.9 gm%) and neutrophilic leukocytosis (total leucocyte count 18,000/cu.mm). His current fasting plasma glucose(224mg/dl), post prandial plasma glucose(356mg/dl) and glycosylated hemoglobin (HbA1c) levels (11.9%, normal < 6.5%) were significantly elevated. Renal function tests were as follows: serum creatinine (2.4mgdl, normal: 0.8-1.5), serum urea (71 mg/dl, normal:20-40), serum sodium (135 meq/l) and serum potassium (5.1 meq/l). Inflammatory markers like serum C-reactive protein (CRP) (28.9mg/dL, normal:1-5) and erythrocyte sedimentation rate (80 mm/hr, normal:0-20 mm/hr) were significantly elevated. Serum creatinine phosphokinase (CPK) level (215IU/L, normal: 46-171) was raised. Blood culture revealed no growth. Chronic diabetic complications assessment revealed presence of moderate non-proliferative diabetic retinopathy, distal symmetrical polyneuropathy and chronic kidney disease. Doppler ultrasonography of bilateral lower limbs revealed presence of diffuse subcutaneous oedema of affected right thigh without evidence of deep vein thrombosis or significant occlusive atherosclerotic disease. Magnetic resonance imaging (MRI) of the right leg revealed presence of diffuse subcutaneous edema, intramuscular fascial edema and increased T2 signal intensity in affected muscle groups. A diagnosis of DMI affecting the right thigh was made. The patient was managed with insulin therapy for glycemic control, limb rest, judicious analgesic use and physical therapy resulting in improvement of his overall clinical status.

Discussion:

Diabetic muscle infarction is a rare and serious complication seen in long-standing poorly controlled diabetes whose exact aetiopathogenesis remains poorly understood. It usually presents with the abrupt onset of pain, tenderness, and swelling of affected limb. The most common affected regions include thigh and calf muscles though other muscle groups may also be affected. The important differentials include muscle abscess, hematoma, deep vein thrombosis and myositis. MRI plays an invaluable role in arriving at correct diagnosis and muscle biopsy (though diagnostic) is very rarely needed. Knowledge of this relatively rare entity will be helpful for early identification and appropriate management.