Uncommon presentation of a common condition: an easily missed cause of hip pain.

Conventionally, patients presenting with hip pain and restricted mobility to accident and emergency (A&E) department are thought to have musculoskeletal pain. Occasionally, patients with significant abdominal pathology can present with hip pain. Such atypical presentation causes the delayed diagnosis leading to significant morbidity and possible mortality. We report a 63-year-old man who had been treated in A&E on numerous occasions with left hip pain for over 6 weeks. On this occasion, he had been brought in septic shock. On examination, he had subcutaneous emphysema of left lower limb. A CT scan showed a large psoas abscess resulting from retroperitoneal perforation of sigmoid diverticulitis tracking into his left lower limb. He underwent a Hartmann's procedure and drainage of his intra-abdominal sepsis. The thigh was not drained with separate incisions at the index operation. Residual thigh abscess was managed by image-guided drainage.