Novel case of diabetic myonecrosis in a teenage patient with type 2 diabetes mellitus

Background

Diabetic myonecrosis is characterised by acute pain and swelling of skeletal muscles, most often in the lower extremities. It is a rare complication of long-standing or poorly controlled diabetes and is typically associated with other microvascular and macrovascular complications of diabetes.1 Although the acute presentation is self-limiting, long-term prognosis in diabetic patients with myonecrosis is poor, with a reported majority of patients dying within 5 years.2

On review of the current literature, the presence of diabetic myonecrosis in younger patient populations has not been well reported. The youngest ages at which an episode of diabetic myonecrosis has been reported was found to be in 19-year-old and 20-year-old women with type 1 diabetes mellitus (T1DM).3 4 We report a case of bilateral diabetic myonecrosis in a 16-year-old patient with type 2 diabetes mellitus (T2DM) and no known prior microangiopathic complications of the disease. To our knowledge, this is the first report of diabetic myonecrosis observed in an adolescent patient with T2DM.

This case demonstrates that myonecrosis can present as an early complication of poorly controlled diabetes and is an important finding as the prevalence of T2DM in adolescent populations continues to increase.5 6 This case also highlights the importance of achieving optimal glycaemic control in younger diabetic populations.

Case presentation

A 16-year-old girl presented with 1 day of severe bilateral calf pain and tenderness. Her medical history was notable for T2DM since the age of 11–12 years, obesity (body mass index 41.8 kg/m²), depression, anxiety, bipolar-type schizo-affective disorder and gastro-oesophageal reflux disease. Notably, the patient’s mother has poorly controlled diabetes with microvascular and macrovascular complications.

The patient presented with sudden-onset, bilateral calf pain that began after a 5-hour road trip, the day prior to admission. Her severe calf pain was described as constant and stabbing. The pain worsened with movement, limiting ambulation. Her medications included insulin degludec, metformin, olanzapine, ziprasidone, buspirone, escitalopram, lamotrigine, famotidine and cetirizine. There was no history of trauma or a fall.

On initial physical examination, the patient was afebrile with stable vital signs. On examination, there was no apparent erythema or induration. Her bilateral gastrocnemius muscles were exquisitely tender and firm to palpation. The patient’s sensation was intact to light touch, vibration, proprioception and temperature in all fields, with intact ankle reflexes. Neurovascular examination was intact with strong dorsalis pedis and tibialis posterior pulses. Homan’s sign for deep venous thrombosis (DVT) was negative.

Investigations

Initial laboratory studies were notable for an elevated creatine kinase (CK) of 2420 U/L (Ref: 26–192 U/L) and C reactive protein of 8.5 mg/L (Ref: ≤5.0 mg/L). Suboptimal glycaemic control was confirmed with a haemoglobin A1c of 10.2% (Ref: 4.3%–5.6%). The remainder of laboratory studies at admission is as follows: glucose 148 (Ref: 60–100 mg/dL), calcium 9.4 (Ref: 8.4–10.2 mg/dL), magnesium 2.1 (Ref: 1.6–2.6 mg/dL), creatinine 0.67 (Ref: 0.57–1.11 mg/dL), aspartate aminotransferase 50 (Ref: 10–35 U/L) and alanine aminotransferase 25 (Ref: 10–35 U/L).

An ultrasound imaging was negative for DVT. The patient’s CK continued to rise, peaking at 4362 U/L (Ref: 26–192 U/L) and normalised after 1 week. A CT imaging of the lower extremities revealed muscle oedema, consistent with myositis. Subsequent MRI of the lower extremities showed multiple areas of patchy oedema and bilateral enhancement of the medial gastrocnemius heads, suggestive of myonecrosis (figure 1). Autoimmune labs and myositis panels including antinuclear, anti-Sjogren’s syndrome A, anti-Sjogren’s syndrome B, anti-Smith, anti-ribonucleoprotein, anti-topoisomerase I, anti-histidyl transfer RNA synthetase and anti-signal recognition particle antibodies were unremarkable.

Histological examination of a left gastrocnemius muscle biopsy revealed acutely necrotic myofibres and phagocytosis of the necrotic cells (figures 2 and 3) consistent with a diagnosis of diabetic myonecrosis.4 7 Immunostains were obtained due to the presence of perivascular and interstitial mononuclear infiltrate. A majority of these cells were positive for CD3, indicative of a T-cell dominant lymphocytic inflammatory process with no evidence of Major Histocompatibility Complex I upregulation.

Treatment

While awaiting biopsy results, therapeutic management was started with intravenous fluids, given her elevated CK, and low-dose aspirin (81 mg) daily. On the 5th day of admission, aspirin was temporarily replaced with naproxen 550 mg two times per day in the setting of persistent pain limiting participation with physical therapy (PT), scheduled four times a week. On the 9th day of admission, given improvement in pain, naproxen was discontinued, and the patient was restarted on low-dose aspirin (81 mg) daily until her pain resolved. During admission, the patient’s olanzapine and ziprasidone were initially held due to concern for medication-induced myopathy. Subsequently, ziprasidone was restarted for the patient’s schizo-affective disorder after a discussion of risks and benefits with psychiatry. The patient received a total of 11 days of treatment in the hospital and was discharged on low-dose aspirin until follow-up with an outpatient doctor.

Prior to admission, the patient was reportedly taking 70 units of insulin degludec once daily and 500 mg of metformin two times per day. While admitted, the patient’s metformin was held, and she was started on insulin glargine and insulin aspart for basal-bolus coverage. The units of her basal-bolus regimen while admitted were adjusted as needed to improve overall glycaemic control, with a goal of maintaining glucose levels between 140 and 180 mg/dL (Ref: 60–100 mg/dL). The patient was discharged on 1000 mg of metformin two times per day and 70 total daily units of 70:30 insulin isophane/insulin regular. She also received education from nutritionists and diabetes educators regarding lifestyle modifications during her hospitalisation.

Outcome and follow-up

During admission, the patient progressed well with treatment. Initially, severe pain limited her ability to participate in PT. With adequate pain control, the patient continued to work with PT and regained functional mobility. Initially she required a rolling walker, however, by the time of discharge, did not require any assistance with ambulation. The patient’s CK had normalised to 149 (Ref: 26–192 U/L) during the course of her admission and the patient’s blood glucose on the 2 days prior to discharge ranged from 89 to 168 mg/dL (Ref: 60–100 mg/dL). Due to changes in social circumstances, the patient moved out of the area and was lost to follow-up. The current health status of the patient presented in this case is unknown.