Pyomyositis Diagnosed by Point-of-Care Ultrasound in the Emergency Department.

Background: Currently, the role of ultrasound in diagnosing superficial abscesses is well validated, however, its role for deep space infections and intramuscular pathology is limited. Distinguishing between simple cellulitis and abscess is critical for emergency physicians (EP), as the treatment is very different. Management of cellulitis relies on antibiotic therapy, whereas abscess treatment requires incision and drainage. It is important that EPs can accurately distinguish between the two entities.

Case Report: We report a case of a 41-year-old man with a history of high blood pressure and poorly controlled diabetes who presented with right lateral thigh redness, warmth, and tenderness. A point-of-care ultrasound (POCUS) of the patient's right lateral thigh with a high-frequency linear (8 MHz) ultrasound probe showed a 2.93 × 3.38 × 6.0-cm complex fluid collection deep to the fascial plane, approximately 3.0 cm from the skin surface, that contained mixed echogenicities with posterior acoustic enhancement consistent with an intramuscular abscess of the vastus lateralis. The patient was diagnosed with pyomyositis of his vastus lateralis. He was started on vancomycin and admitted to the surgical service for antibiotic treatment and surgical drainage. WHY SHOULD EMERGENCY PHYSICIANS BE AWARE OF THIS?: This case demonstrates that the use of POCUS by EPs can facilitate the rapid recognition and treatment of a disease that is challenging to diagnose on physical examination and can be potentially life-threatening if missed. EPs can consider performing a POCUS when evaluating skin infections to ensure rapid diagnosis and appropriate medical care for a potentially severe condition.