A rare presentation of iliopsoas abscess - A case report.

Introduction: Psoas abscesses are usually confined to the psoas compartment due to its fascial attachments. However, in rare situations, the infection can locally spread beyond the psoas sheath.

Case Presentation: A 65-year-old patient presented with; 3 weeks of lower back and right hip pain, progressive inability to walk and one week of urinary incontinence. CT abdomen showed a right psoas abscess with pneumo-retroperitoneum extending to the right gluteus muscle, posterior compartment of the upper thigh and mediastinum. Exploration in theatre showed copious amounts of pus, visible between the fascial layers and muscles of the thigh, tracking to the level of the knee and the gluteal region.

Discussion: Psoas abscesses are usually confined to the psoas compartment. However, in this case, it was spread to the posterior compartment of the thigh, gluteal region and pelvis with fascial necrosis and pus. Due to the extensive nature of the disease and the patient's clinical deterioration, he underwent open drainage of the psoas abscess, exploration and debridement of the posterior compartment of thigh and gluteal region with a good outcome.

Conclusion: Psoas abscesses can penetrate the psoas sheath to cause extra pelvic extension. A high index of suspicion and early imaging, if necessary, should be arranged if in doubt. Depending on the clinical severity, patients may need to be managed with open drainage and debridement than conventional CT-guided drainage.