Diabetic Myonecrosis: An Unusual Suspect

Author: M. Auron, M.D, Department of Hospital Medicine, Cleveland Clinic
Reviewer: V. Dimov, M.D., Department of Hospital Medicine, Cleveland Clinic

A 42-year-old male immigrant from South America with poorly controlled DM type 2 (HbA1c 13%) and hypertension presented with a one-month history of progressively worsening pain in his left thigh and calf associated with secondary inability to walk. There was no history of trauma or intramuscular injections.

Medications

Insulin 70/30 bid, lisinopril 20 mg daily, ASA 81 mg daily and simvastatin 40 mg daily.

Physical examination

Afebrile, and there was no evidence of arthritis or effusion. There was swelling and tenderness in the left distal quadriceps area and calf with limited range of motion of the knee. Peripheral pulses and sensation were normal.

What is the most likely diagnosis?

In the setting of poorly controlled diabetes, diabetic myonecrosis should be considered highly in the differential, as well as infection of the muscle such as pyomyositis or necrotizing fasciitis. However, being on statins should prompt to rule out rhabdomyolysis. On the other hand, is an immigrant from South America, therefore, trichinosis (infection by Trichinella spiralis) should be considered as well. As the patient has been sedentary, deep venous thrombosis should be excluded.

What tests would you order?

Complete blood count with differential – to rule out infection, and in te differential, the presence of eosinophilia would suggest a parasitic infection such as Trichinella. Basic chemistry profile (BMP), creatine kinase (CK), aldolase. As well would do imaging of the leg with a Doppler ultrasound to rule-out deep venous thrombosis. A CT scan or an MRI of the thigh would offer the best imaging modality of musculoskeletal system.

Laboratory results

- Normal chemistry without azotemia, normal white blood cell count and normal creatine kinase (CK) and aldolase levels.
- Deep venous thrombosis was excluded with a Doppler ultrasound.
- Left knee X-Ray was unremarkable.
- A Magnetic Resonance Imaging (MRI) of his left knee showed swelling and signal alteration involving the distal aspect of the vastus medialis, with hyperintensity on T2 weighted images, and iso to slightly hyperintense on T1 weighted images, compatible with necrosis.



What treatment would you start for this patient?

The patient was treated conservatively with limb elevation, avoidance of weight bearing and analgesics with progressive improvement. He was discharged after diabetic education and management strategies.

What happened?

This patient was readmitted to general medical floor again after two months with pain in the contralateral thigh and MRI of that thigh show findings consistent with necrosis of the thigh muscles.

Final diagnosis

Diabetic myonecrosis.

What did we learn from this case?

• Diabetic myonecrosis is a rare and often-missed disease that occurs in patients with poorly controlled diabetes.
• Any diabetic patient who presents with thigh pain and swelling should be considered for this diagnosis.
• MRI is a very important tool for diagnosis with very good sensitivity and it helps in differentiating this diagnosis from other closely mimicking diagnoses.
• Although biopsy is the "gold standard" for diagnosis, it should be avoided if possible for the risks of delayed healing and superimposed infection.
• Treatment is supportive, and the symptoms resolve within weeks to months. Risk of recurrence in the same or opposite leg is high.
• Long term prognosis of patients with diabetic myonecrosis is poor, since this is a marker for significant vascular complications of diabetes mellitus.
• Awareness of this syndrome and MRI as first diagnostic test should lead to the correct diagnosis and shorter hospitalization.

References

1. Kermani T, Baddour LM. Diabetic muscle infarction mistaken for infectious cellulitis.Ann Intern Med. 2006 Oct 3;145(7):555-6 .
2. Kapur S, Brunet JA, McKendry. RJ. Diabetic muscle infarction: case report and review. J Rheumatol. 2004 Jan;31(1):190-4.
3. Keller DR, Erpelding M, Grist T. Diabetic muscular infarction. Preventing morbidity by avoiding excisional biopsy. Archives of Internal Medicine 1997 Jul 28;157(14):1611
4. Umpierrez GE, Stiles RG, Kleinbart J, Krendel DA, Watts NB. Diabetic muscle infarction. Am J Med. 1996;101:245-50
5. Kattapuram TM, Suri R, Rosol MS, Rosenberg AE, Kattapuram SV. Idiopathic and diabetic skeletal muscle necrosis: evaluation by magnetic resonance imaging. Skeletal Radiol. 2005;34:203-9.

Published: 01/21/2008
Updated: 12/11/2009

1 comment:

  1. uttam bhatta12/11/2009 2:53 AM

    thanks to all for this case study
    at least i will think of this differential while working on such complaints.
    uttam bhatta
    Nepal

    ReplyDelete