BACKGROUND: Necrotizing myopathies and muscle necrosis can be caused by immune-mediated mechanisms, drugs, ischemia, and infections, and differential diagnosis may be challenging.
METHODS: We describe a case of diabetic myonecrosis complicated by pyomyositis and abscess caused by Escherichia coli. A white woman in her late forties was admitted to the hospital with a 1.5 week history of bilateral swelling, weakness, and mild pain of the lower extremities and inability to walk. She had a history of type 1 diabetes complicated by diabetic retinopathy, neuropathy, nephropathy, and end-stage renal disease. C-reactive protein was 203 mg/l, while creatinine kinase was only mildly elevated to 700 IU/l. Magnetic resonance imaging of her lower limb muscles showed extensive edema, and muscle biopsy was suggestive of necrotizing myopathy with mild inflammation. No myositis-associated or myositis-specific antibodies were detected. Initially, she was suspected to have seronegative immune-mediated necrotizing myopathy, but later her condition was considered to be explained better by diabetic myonecrosis with multifocal involvement. Her symptoms alleviated without any immunosuppressive treatment. After a month, she developed new-onset and more severe symptoms in her right posterior thigh. She was diagnosed with emphysematous urinary tract infection and emphysematous myositis and abscess of the right hamstring muscle. Bacterial cultures of drained pus from abscess and urine were positive for Escherichia coli. In addition to abscess drainage, she received two 3-4-week courses of intravenous antibiotics. In the discussion, we compare the symptoms and findings typically found in pyomyositis, immune-mediated necrotizing myopathy, and diabetic myonecrosis (spontaneous ischemic necrosis of skeletal muscle among people with diabetes). All of these diseases may cause muscle weakness and pain, muscle edema in imaging, and muscle necrosis. However, many differences exist in their clinical presentation, imaging, histology, and extramuscular symptoms, which can be useful in determining diagnosis. As pyomyositis often occurs in muscles with pre-existing pathologies, the ischemic muscle has likely served as a favorable breeding ground for the E. coli in our case.
CONCLUSIONS: Identifying the etiology of necrotizing myopathy is a diagnostic challenge and often requires a multidisciplinary assessment of internists, pathologists, and radiologists. Moreover, the presence of two rare conditions concomitantly is possible in cases with atypical features.

Diabetic myonecrosis is a rare and poorly understood complication of long-standing, inadequately controlled diabetes mellitus. Theoretical mechanisms contributing to the pathophysiology of diabetic myonecrosis include microvascular complications due to advanced glycation end-products, ischemia-reperfusion injuries, and dysregulated coagulation-fibrinolysis activity. Case reports of diabetic myonecrosis most commonly describe diabetic patients with chronically poor glycemic control who experience isolated swelling and severe pain in a unilateral lower limb with no signs of infection or systemic toxicity. Due to the rarity of this condition, there are currently no treatment guidelines. This case describes a 58-year-old male with a history of uncontrolled diabetes who presented with diabetic ketoacidosis with mixed hypovolemic and septic shock. Diabetic myonecrosis was incidentally discovered in the patient\'s right latissimus dorsi with CT imaging and subsequent surgical exploration. Spontaneous diabetic myonecrosis may mimic several other serious conditions and elicit suboptimal management strategies, particularly in the context of atypical presentations.

Diabetic myonecrosis is an infrequently encountered complication of poorly managed type 2 diabetes. Despite its relative rarity, early detection and appropriate management can yield favorable outcomes. This case report details the presentation, diagnosis, and management of a 53-year-old male patient with a history of type 2 diabetes who presented with acute-onset pain, swelling of the muscles, and weakness. Following a battery of laboratory investigations, radiological imaging, and a muscle biopsy, the patient was diagnosed with diabetic myonecrosis. The patient was treated conservatively with analgesics, physiotherapy, and optimization of glycemic control, significantly improving muscle strength and function. This case highlights the necessity of considering diabetic myonecrosis as a potential differential diagnosis in diabetic patients who present with sudden muscle weakness and discomfort.

Diabetic myonecrosis, also known as diabetic muscle infarct, is a rare complication of diabetes mellitus, generally associated with poor glycemic control. It is often difficult to diagnose due to its nonspecific presentation and lack of awareness of the complication. Routine laboratory investigations often do not aid in diagnosis. Magnetic resonance imaging (MRI) may assist in diagnosis but is not routinely ordered due to cost-effectiveness and nonspecific radiologic appearance. Muscle biopsy can provide a definite diagnosis; however, it is often avoided due to its invasiveness. Treatment consists of glycemic control, rest, and analgesics for pain control. Our case describes a 42-year-old male with uncontrolled diabetes who presented with four weeks of progressively worsening right-sided lower extremity pain. The patient was taken to the operating room for concern for necrotizing fasciitis; however, it was ultimately ruled out. A diagnosis of diabetic myonecrosis was made. Recommendations were given for strict blood sugar control and to start aspirin 81 mg daily. The patient was later seen in the outpatient clinic with improvement in the lower extremity pain.

Diabetic myonecrosis (DMN) is a rare microangiopathic disorder that can present as an acutely painful and swollen limb in patients with established diabetes mellitus. The condition can be diagnosed noninvasively with magnetic resonance imaging and resolves with analgesia, bed rest, and glycemic control. Due to a relative lack of awareness regarding the condition, avoidable interventions such as muscle biopsies and even surgery are sometimes pursued, which have been associated with prolonged recovery times. The majority of patients with DMN have diabetic nephropathy, yet this condition is not widely recognized in the nephrology community, resulting in delayed diagnosis and patients undergoing unnecessary and potentially harmful investigations. There is therefore a need for increased awareness of the condition among renal physicians. Here, we report the cases of two patients on hemodialysis who were ultimately diagnosed with DMN, along with a review of the literature.

Cystic fibrosis is a recessive autosomal disease caused by mutations in the cystic fibrosis transmembrane conductance regulator gene. Cystic fibrosis-related diabetes (CFRD) is a common comorbidity of cystic fibrosis. Diabetic myonecrosis is a rare self-limited complication of poorly controlled diabetes mellitus that commonly presents with acute, intense pain and swelling of lower extremities and responds well to conservative management. We report the first case of diabetic myonecrosis in a patient with CFRD.