Article in Japanese

A case of obturator externus muscle pyomyositis after overloading the hip joint

Tomoki IIO^1） , Shingo KOBARI^1） , Atsushi ISOZAKI^1）

Most cases of pyomyositis are reported after school age. We have experienced a case of obturator externus muscle pyomyositis in infants after overloading the hip joint. A naturally healthy 5-year-old boy visited the emergency department on the third day of fever and right hip and knee joint pain after 3 h of playing on a foot pedal car for ages 2‒3 years. Blood tests revealed an elevated inflammatory reaction, and the patient was admitted to the hospital for further investigation and treatment. Methicillin-sensitive Staphylococcus aureus was isolated and identified from two blood culture sets obtained during admission, and a simple hip joint magnetic resonance imaging showed high signal of T2WI in the right external obturator muscle, leading to the diagnosis of obturator externus muscle pyomyositis. After admission, the patient was treated with cefazolin and responded well. The patient was treated with antimicrobial agents for 4 weeks without relapse. Considering obturator muscle pyomyositis in infants who complain of fever and hip pain and have an elevated inflammatory reaction after excessive exercise is important.

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1）Department of Pediatrics, Minato Red Cross Hospital

Key words	obturator externus muscle pyomyositis, infants, exercise stress
Received	May 9, 2022
Accepted	September 30, 2022

34 (4)：277─284,2022