Upper-Limb Diabetic Myonecrosis: Atypical Presentation of a Rare Complication

Patient: Female, 55 Final Diagnosis: Diabetic ischemic myonecrosis of left arm (biceps muscle) Symptoms: Erythema • pain upper arm • swelling Medication: — Clinical Procedure: Supportive therapy with analgesics • blood glucose control Specialty: Rheumatology OBJECTIVE: Rare disease BACKGROUND: Myonecrosis is an uncommon complication of poorly controlled diabetes, predominantly involving the lower limbs. It is an atypical presentation in the upper limbs. Here, we report a rare case with atypical involvement of the upper limbs. CASE REPORT: A 53-year-old diabetic woman presented with left arm pain for the past week. She was not compliant with her medications. The patient denied any history of trauma or injection. Physical examination revealed a warm, tender, and erythematous swelling on the medial side of the left arm and was otherwise unremarkable. Her glycemic control was poor, with Hb A1C of 9.6%. Duplex ultrasonography demonstrated no evidence of fluid collection or thrombosis. An initial MRI (without contrast) report was misleadingly suggestive of polymyositis. Orthopedic consultant urged the patient to transfer to the operating room for aspiration of a probable infectious nidus, which resulted in a dry tap. Despite confusing radiological clues, ischemic myonecrosis was suspected, and second MRI studies (with contrast) reported necrosis. Tissue biopsy (the criterion standard) was withheld to avoid the risk of delayed healing or superimposed infection. Meanwhile, the patient received supportive treatment and achieved full recovery within 1 month. CONCLUSIONS: Diabetic myonecrosis should be suspected in any poorly controlled diabetic patient presenting with otherwise unexplained muscle pain without any evidence of infection. Diagnosis can be made by MRI, leaving very few indications for invasive procedures. Analgesics and glycemic control are the mainstays of treatment.