Case Presentation: A 26 year-old female with past medical history of Type I Diabetes Mellitus (DM), presented to the emergency room with acute onset of severe myalgias. Vital signs were normal. Her exam was notable for severe tenderness to light palpation of the anterior bilateral quadriceps and bilateral trapezius muscles, along with severe immobility secondary to pain with active and passive motion. Review of systems was negative for focal deficits, sensory loss, or incontinence. Admission labs were significant for ESR >100 mm/hr, CRP 3.4 mg/dL, WBC 13.7 B/L, creatine kinase 26 IU/L, and hemoglobin A1c 13.9%. ANA, c-ANCA, p-ANCA, and anti-Jo-1 antibodies were negative. Infectious work up was negative. MRI thighs showed diffuse myositis involving the quadriceps muscles of both lower extremities, with discrete areas of myonecrosis. Given poor glycemic control, mild leukocytosis, elevated inflammatory markers, negative rheumatologic and infectious workup, and imaging findings, the patient was diagnosed with diabetic myonecrosis. The patient’s diabetic control and pain control were optimized, she was started on a daily aspirin, and she was discharged to a sub-acute rehabilitation center to increase performance of activities of daily living.
Discussion: Diabetic myonecrosis is a rare complication of poorly controlled DM. According to a 2015 systemic review, 126 cases have been reported over a 45-year time-frame. The mean age of presentation varies by diabetes sub-type, with 35.9 years and 52.2 years for type I and type II DM, respectively. 1 The pathophysiology is unclear, however theories include secondary to atherosclerosis, diabetic microangiopathy, ischemia-reperfusion injury, or vasculitis with thrombosis. Diagnostic suspicion should be high when a patient with poorly controlled DM presents with acute myalgia. History is significant for being afebrile, no recent trauma, and acute-onset muscle pain, most commonly including the thighs. Laboratory findings may show a leukocytosis and elevated inflammatory markers. Definitive diagnosis requires muscle biopsy, however this is not recommended due to increased risk of complications given underlying muscle injury. Therefore, MRI is preferred in suspected cases as the sensitivity and specificity are sufficient enough to make a diagnosis.2 A systemic review found MRI showed edema and T2 hyperintensity in 76.8% of cases. Additionally, MRI is able to identify specific infarcted muscle groups. Ultrasonography has also been recommended and would show well-marginated, hypoechoic intramuscular lesion. Management consists of rest, analgesia with NSAIDs (if not contraindicated), and strict glycemic control. A single study showed low-dose aspirin shortened recovery time to 39 days from 57 days when treated with rest and analgesia alone. 3 Physical therapy is generally not recommended as this can prolong recovery time due to ongoing stress of injured muscle.
Conclusions: In summary, diabetic myonecrosis is a severe complication of DM that may go unrecognized due to its rarity. More research in the pathophysiology and management of myonecrosis is needed given how little is known about its long-term clinical course.