Pyomyositis

Pyomyositis

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  Noon Conference Sarah Kerr,MS3
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  Summary Statement Patient isa 59-year-old man with ALL who presented for cycle 2B of hyper-CVAD chemotherapy but on further evaluation was found to have leukocytosis, as well as worsening R elbow and R thigh erythema, edema and pain. DDx?
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  Imaging • MRI UpperExtremity: Myositis; no evidence of abscess, osteomyelitis or septic arthritis. • MRI Lower Extremity: Focal intramuscular abscess in the biceps femoris muscle with mild necrosis of the surrounding tissue.
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  Pyomyositis • A purulentinfection of skeletal muscle that arises from hematogenous spread of bacteria – usually with abscess formation. • Predisposing factors: immunodeficiency, trauma, injection drug use, concurrent infection.
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  Pyomyositis • Most commonpathogen = staph aureus (MRSA in up to 25% of these cases). • E. Coli pyomyositis emerging infection in those with hematologic malignancy.
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  Clinical Presentation FEVER, LOCALIZEDCRAMPY MUSCLE PAIN, SWELLING • 3 clinical stages • Greater than 90% of patients present with stage 2: occurs 10-21 days after onset of symptoms and can be characterized by fever, exquisite muscle tenderness, edema, marked leukocytosis. Frank abscess MAY be clinically apparent. Aspiration yields pus.
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  Diagnosis • MRI • Fluidcultures
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  Treatment • Patients whopresent with stage 2 or 3 usually require drainage in addition to antibiotic therapy. • Immunocompetent: vancomycin. • Immunocompromised: vancomycin + broad- spectrum coverage for gram neg. and anaerobes.
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  Pyomyositis Polymyositis Pathophysiology Hematogenousspread of bacteria in immunocompromised patient Autoimmune Clinical Presentation Fever, swelling, crampy localized muscle pain Symmetric proximal muscle weakness Diagnostics MRI, Fluid aspirate Muscle enzymes, +ANA/anti-jo-1, muscle biopsy Treatment Broad-spectrum antibiotics Corticosteroids, methotrexate