A 42-year-old female patient presented with complaint of pain and swelling in the right calf for the last 2 months (Fig. 1a). There was no history of fever. She was a known case of type 2 diabetes mellitus (T2DM) for the last 11 years, hypertensive for the last 1 year and hypothyroidism for the last 2 months. Patient underwent hysterectomy 3 years back. There was no history of trauma, i.m. injection, arthralgia or other systemic symptoms.
Q What would you suspect when a diabetic patient presents with history of pain and swelling of calf muscles ?
My differential diagnosis would be
- Deep vein thrombosis
- Baker’s cyst
- Calf muscle tear
- Venous valvular insufficiency.
- Diabetic myonecrosis
On examination, right leg was swollen, tender and indurated.
Q What investigation would you order ?
- Compression ultrasonography of the lower limb (venous doppler with compression)
Q Is diabetes a risk factor for DVT ?
It is controversial. Diabetes per se is not a risk factor for DVT. In a study conducted by Heit et al ,they found incidence of DVT in diabetics no different from general population.
On evaluation, patient had all microvascular complications of diabetes.
- What is the importance of knowing that this patient has other diabetic microvascular complications in this case ?
- Presence of other microvascular complications increases the risk of patient have diabetic foot with cellulitis
- Diabetic myonecrosis is also considered a vascular complication of diabetes and presence of other microvascular complications increases the likelihood of patient having diabetic myonecrosis.
Investigation revealed hemoglobin of 7 g/dl (11–15 mg/dl), total leucocyte count 10 200/mm3 (4000–11 000/mm3), platelets 293×103/mm3, peripheral blood film suggestive of microcytic hypochromic red blood cell, urea 72 mg/dl (10–50 mg/dl), creatinine 3.2 mg/dl (0.5–1.2 mg/dl), HbA1c 8% (3.8–5.6%), thyroid-stimulating hormone (TSH) 10.8 μIU/ml (0.27–4.2 μIU/ml), thyroxine (T4) 6.98 μg/dl (4.8–12.7 μg/dl), tri-iodothyronine (T3) 0.8 ng/ml (0.8–2.0 ng/ml), 24 h urinary protein 550 mg/day and CK 403.5 U/l (26–308 U/l). ANA, ANCA, RA factor, dsDNA, SSA/RO, SSB/LA, Sm, Sm/RNP, Scl70, Jo1 were negative and coagulation profile was normal.
- What other condition in this patient could have led to myalgia and raised CK levels ?
Fundus examination revealed hard exudates. Blood culture was sterile. Deep vein thrombosis (DVT) was excluded by compression ultrasonogram (USG).
Q What would you consider next ?
Since the diagnosis is still not clear, I would advise and MRI of the limb.
USG of the right leg was suggestive of diffuse thickening and increased echogenicity of skin and subcutaneous tissue along with marked swelling and hypoechogenicity of muscles without any localized collection. MRI right leg revealed thickening and edema of the skin/subcutaneous tissue with hyperintensity in muscles of all the compartments of the right leg in short tau inversion recovery (STIR) sequence (Fig. 1b and c). Electromyography (EMG) was suggestive of inflammatory myositis. Muscle biopsy (Fig. 1d) from right gastrocnemius was performed as calf muscle involvement is relatively uncommon in Diabetes myonecrosis. Patient was diagnosed to have Diabetes myonecrosis and was treated conservatively with paracetamol and tramadol with complete recovery within 6 weeks. The dose of levothyroxine was also optimized.
Q What is diabetic myonecrosis ?
It is spontaneous infarction of muscles in diabetic patients which is unrelated to atheroembolism or occlusion of any major arteries.
Q It is common in what type of diabetics ?
It is more common in long standing uncontrolled diabetics. It is more common in type 1 diabetics.
Q Which muscles are commonly involved in this conditions ?
Muscles of thigh and calf are commonly involved. Quadriceps muscle is most commonly involved. It may present acutely and the involved muscle may be tender. Patient may run mild fever. The condition tends to recur after resolution.
Q Is the creatinine kinase elevated in these patients ?
As seen in this case CK may be elevated but only mildly in patients with Diabetic myonecrosis.
Q What does MRI in such cases show ?
- High signal intensity in T2W image in the involved muscles
- Post gadolinium contrast there is patchy enhancement of the involved muscles. While the infarcted muscle shows no enhancement , the surrounding edema and inflammation shows reasonable enhancement.
- Loss of fatty intermuscular septae
Q What is the treatment of diabetic myonecrosis ?
Treatment is mainly conservative with rest and NSAIDS. It spontaneously resolves in a few weeks.