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.

Pyomyositis is a bacterial infection of skeletal muscle leading to abscess formation. Younger males are predominantly involved, but pyomyositis may occur in all ages and sexes. Underlying systemic disease or accompanying immunocompromised states may increase the risk of pyomyositis. This is a report of a 72-year-old, male, with uncontrolled diabetes mellitus, presenting initially as a case of orbital cellulitis. Magnetic resonance imaging confirmed the presence of an abscess in the left lateral rectus. Antibiotic therapy was promptly initiated, and drainage of the abscess was performed via a transconjunctival approach. Pyomyositis resolved post-surgery and medical therapy. Residual exotropia was noted at the eighth month of follow-up necessitating subsequent strabismus surgery. Nine months post-treatment, left lateral rectus pyomyositis did not recur.

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Pyomyositis is an uncommon primary infection of skeletal muscle resulting in muscle inflammation followed by pus formation. Pyomyositis is typically caused by Staphylococcus aureus (S. aureus), and most cases are associated with skin penetration and/or immunosuppressive conditions in tropical or even temperate climates. We report a previously healthy, immunocompetent 44-year-old man who presented with fever and right lower back pain. He had received an analgesic injection for his back pain 12 days prior to this visit. His clinical course was further complicated by the coexistence of multiple muscular abscesses, renal infarction, and septic arthritis of the right shoulder. He underwent computed tomography-guided drainage of the abscess. The abscess and blood cultures were positive for methicillin-susceptible S. aureus. The patient responded well to prolonged treatment with cefazolin and cephalexin and was discharged 12 weeks after initial admission.

Tubercular pyomyositis is a rare but distinct clinical entity which is difficult to diagnose especially in a patient with underlying autoimmune disease. The treatment is even more challenging if it is a multi-drug resistant strain. Here we report a patient with primary Sjögren\'s syndrome who presented with persistent inflammation of his right arm which was later diagnosed as multi-drug resistant tubercular pyomyositis. This case highlights the need for a high index of suspicion for tuberculosis in all cases of pyomyositis.

In patients with infectious symptoms and severe muscle pain, it is crucial to consider pyomyositis as a significant potential cause. A normal complete blood count should not exclude this possibility early in the course. Early advanced imaging modalities and blood cultures are crucial in narrowing the differential. Methicillin resistant Staphylococcus aureus is increasingly implicated.

BACKGROUND: Pyomyositis generally occurs in otherwise healthy young men. Because this condition is unusual among otherwise healthy women in temperate climates, we present the following case.
METHODS: An otherwise healthy 43-year-old woman presented with bilateral pain in her lower extremities and fever. Magnetic resonance imaging (MRI) findings were indicative of myositis with a possible abscess. We initiated empirical antibiotic therapy with ceftriaxone. However, the swelling and pain in her legs persisted even after 7 d of treatment. Contrast MRI revealed multiple pockets of pus in the vastus lateralis and gluteal muscles. We performed needle aspiration of these abscesses with ultrasound guidance and local anesthesia. Upon culturing, the purulent material was positive for Staphylococcus aureus. We diagnosed her with S. aureus-induced pyomyositis of the vastus lateralis muscle and gluteus region. Based on the antibiotic sensitivity report, ceftriaxone was administered for an additional 7 d. By day 15 post-drainage, the patient was able to start walking. Oral antibiotic therapy was continued for 1 wk following her discharge from hospital, after which her symptoms resolved completely.
CONCLUSIONS: Pyomyositis may present with muscle pain, swelling, and fever. Ultrasound-guided percutaneous puncture and drainage may enable timely diagnosis and treatment.

Pyomyositis which is also known as myositis tropicans is a rare condition where there is bacterial infection of the skeletal muscle. Its manifestation includes pain and tenderness of the affected muscle and general infective symptoms. It commonly occurs in immunocompromised individuals and patients with previous history of trauma to the affected muscle. We report a case of a 16-year-old boy with history of underlying bronchial asthma who presented with multiple abscesses. He underwent multiple operations to drain the infection and targeted antibiotic therapy subsequently. Despite undergoing surgical debridement, drainage and antibiotic treatment, he was still having repeated bouts of fever and his inflammatory markers were not reducing. He was then diagnosed with concurrent pulmonary tuberculosis infection which subjected him to an immunosuppressed state thus arising to the condition of pyomyositis and unresolving fever. The patient then made prompt improvement when the underlying cause of immunosuppression; pulmonary tuberculosis was treated as well.

BACKGROUND: Pyomyositis is an unusual bacterial infection but potential severe in children. Staphylococcus Aureus is the main caused of this disease (70-90%), following by Streptococcus Pyogenes (4-16%). Streptococcus Pneumoniae rarely caused invasive muscular infections. We describe a case of pyomyositis caused by Streptococcus Pneumonia in an adolescent 12-year-old female.
METHODS: I.L. referred to our hospital for high fever associated with right hip and abdominal pain. The blood exams showed increase of leukocytes with prevalence of neutrophils with high level of inflammatory markers (CRP 46,17 mg/dl; Procalcitonin 25,8 ng/ml). The abdomen ultrasonography was unremarkable. The CT and MRI of the abdomen and right hip revealed pyomyositis of the iliopsoas, piriformis and internal shutter associated with collection of pus between the muscular planes (Fig. 1). The patient was admitted to our paediatric care unit, and she was initially treatment with intravenous Ceftriaxone (100 mg/kg/day) and Vancomycin (60 mg/kg/day). On day 2, a pansensitive Streptococcus Pneumoniae was isolated from the blood culture, and the antibiotic treatment was changed to only IV Ceftriaxone. She was successively treated with IV Ceftriaxone for 3 weeks, then continued with oral Amoxicillin for a total of 6 weeks of therapy. The follow up showed a complete resolution of the pyomyositis and psoas abscess after 2 months.
CONCLUSIONS: Pyomyositis associate with abscess is a rare and very dangerous disease in children. The clinical presentation can mimic symptoms of other pathologies like osteomyelitis or septic arthritis, so many times is hard to identify. The main risk factors include story of recent trauma and immunodeficiency, not present in our case report. The therapy involves the antibiotics and, if possible, abscess drainage. In literature there is much discussion about duration of antibiotic therapy.

A 6-year-old girl was brought to the emergency department with a history of an accidental fall a few days earlier. She presented with a fever, cough and constipation. Sars-CoV-2 infection being suspected, she was transferred to a paediatric facility for Covid-positive patients. During the diagnostic process, the clinical picture suddenly deteriorated with the development of bradycardia, tachypnea and altered sensorium. Despite cardiopulmonary resuscitation attempts, the child died about 16 hours after admission to the emergency department. A judicial forensic autopsy was performed that concluded that her death was due to multiple acute pulmonary, cardiac and renal infarctions secondary to septic thromboembolism in the course of post-traumatic bacterial necrotizing pyomyositis of the right ileo-psoas muscle.