Iliopsoas abscess is uncommon in children and rare still in neonates.^{[1], [2]}] A 10-day-old female neonate presented to the pediatric surgery emergency with high grade fever and swelling ofthe right upper thigh. The neonate was sick looking, dehydrated, and febrile. The limb swelling was confined to the right medial upper thigh. On careful palpation, a fluctuation bulge could also be appreciated over the right flank. Both the swellings appeared tender to touch. Additionally, the baby had restricted movement of the right lowerlimb and cried on manipulation of the limb. She was started on intravenous ampicillin and cloxacillin antibiotics.Laboratory investigations revealed neutrophilic leukocytosis and elevated C-reactive protein. Blood culture was sterile. Hip joint radiograph ruled out septic arthritis, which was our provisional diagnosis. Spine was also unremarkable. Ultrasound of both swellings depicted it right sided iliopsoas abscess extending from the iliac crest to the medial thigh. Percutaneous drainage attempted but failed due to loculated collection and viscosity of pus. The baby underwent open, extraperitoneal drainage of the collection. Pus microscopy showed scant gram-positive cocci;pus culture was sterile. Systemic antibiotics were continued up to two weeks. The neonate responded well with clinical betterment and normalization of blood counts. Postoperative period was uneventful. Follow-up at six weeks showedno fresh collections with normal limb movements.

Iliopsoas abscess is very rare in neonatal age with less than twenty cases reported till date.^[1] The common presentations are swelling and restricted mobility of limb along with fever as noted in the index case. Unilateral lesions are common, though bilateral cases have also been reported.^[2] The etiology of primary iliopsoas abscess is unknown with hematogenous spread from occult site commonly implicated.^{[1], [4]} Psoas abscess may also be secondary to septic arthritic collections, osteomyelitis of femur, spread from abscess at vaccine site or traumatic cellulitis. None could be found, as an etiology, in the index case. The common causative organisms are Staphylococcus aureus followed by Klebsiella and streptococcus. Ultrasound is the investigation of choice. CT scan may complement by showing the extent of collection and planning drainage. However, CT scan is often not performed due to the acute presentation and radiation hazard to the neonate. Similarly, in the index case, surgical decision making was done based on ultrasonographic findings. Simple medical management is not always sufficient and pus aspiration, or incision and drainage of abscess may be needed.^{[1], [5], [6]} The prognosis stands good with an early recovery in the absence of predisposing factors like immunocompromise status, septic arthritis, spondylodiscitis of spine or MRSA infection.^{[1], [5]} However, a high index of suspicion is warranted to reach the diagnosis in case of primary neonatal iliopsoas abscess.Delay in diagnosis and inadequate pus drainage may lead to sepsis, mortality and sequelae of damage to the joints.^{[1], [6]}