Primary Psoas Abscess in a Pediatric Patient: A Case Report

A psoas abscess is described as a collection of pus in the iliopsoas muscle compartment, which comprises the psoas and iliacus muscles located in the extraperitoneal space. It can be considered a primary abscess due to hematogenous or lymphatic seeding from a distant site, primarily occurring in children in tropical or developing countries. These primary infections are typically due to a single microorganism, most commonly, Staphylococcus aureus. Secondary spread develops due to the direct spread of infection of the psoas muscle from an adjacent structure (hip, vertebrae, gastrointestinal tract, aorta, genitourinary tract), developing due to trauma or instrumentation of the inguinal region, lumbar spine, or hip region. The secondary infections can be either mono- or polymicrobial and include enteric and anaerobic organisms. We present a case of psoas abscess in a five-year-old female who presented with a progressively worsening pain in the right hip for three days with refusal to bear weight and no history of trauma. Hip x-ray imaging yielded no abnormal results, but laboratory values prompted further investigation, leading to identifying a right psoas abscess via MRI with surrounding edema and enhancement. Imaging modality choice has proven to be instrumental in identifying psoas abscess and is key to achieving a diagnosis.