Iliopsoas abscess (IPA) is rare in neonates. We present a case of neonatal IPA that was initially believed to bean inguinal hernia. A 20-day-old male infant was referred to our hospital for herniorrhaphy after a 2-day history of swelling and bluish discoloration of the left inguinal area and leg without limitation of motion. Abdominal and pelvic ultrasonography suggested a femoral hernia, but the anatomy was unclear. Abdominal computed tomography revealed a multi-septated cystic mass extending into the psoas muscle from the lower pole of the left kidney to the femur neck. Broad spectrum antibiotics were initiated, and prompt surgical exploration was planned. After opening the retroperitoneal cavity via an inguinal incision, an IPA was diagnosed and surgically drained. Culture of the abscess fluid detected Staphylococcus aureus, sensitive to methicillin. The patient was discharged without complication on the 17th postoperative day.
Keywords: Infant, Newborn; Psoas Abscess; Staphylococcus aureus.