A case report of an atypical presentation of pyogenic iliopsoas abscess

Iliopsoas abscess is a collection of pus in the iliopsoas muscle compartment. It can be primary or secondary in origin. Primary iliopsoas abscess occurs as a result of hematogenous or lymphatic seeding from a distant site. This is commonly associated with a chronic immunocompromised state and tends to occur in children and young adults. Secondary iliopsoas abscess occurs as a result of the direct spread of infection to the psoas muscle from an adjacent structure, and this may be associated with trauma and instrumentation in the inguinal region, lumbar spine, or hip region. The incidence of iliopsoas abscess is rare and often the diagnosis is delayed because of non-specific presenting symptoms.

We describe a patient with iliopsoas abscess who presented to the Emergency Department at X Hospital on three separate occasions with non-specific symptoms of thigh pain and fever before finally being admitted for treatment. This case illustrates how the diagnosis can be delayed due to its atypical presentation. Hence, highlighting the need for clinicians to have a high index of clinical suspicion for iliopsoas abscess in patients presenting with thigh pain and fever.

The classic triad of fever, flank pain, and hip movement limitation is presented in only 30% of patients with iliopsoas abscess. Clinicians should consider iliopsoas abscess as a differential diagnosis in patients presenting with fever and thigh pain. The rare condition with the varied clinical presentation means that cross-sectional imaging should be considered early to reduce the risk of fulminant sepsis.