Iliopsoas Abscess Misconstrued as Aggravated Ankylosing Spondylitis / 대한내과학회지

ABSTRACT

An iliopsoas abscess is a collection of pus in the iliopsoas muscle caused by the direct spread of infection from adjacent internal organs or by hematogenous or lymphatic spread from distal sites. Its symptoms are vague back, hip, thigh or lower abdomen pain with insidious onset, similar to those of ankylosing spondylitis (AS). Therefore diagnosing an iliopsoas abscess in patients with AS is difficult. A forty-three year-old man was treated with adalimumab, a tumor necrosis factor inhibitor, and clinical symptoms were subsequently observed to improve. One year after voluntary discontinuation of adalimumab, the patient returned with a recurrence of right buttock pain and was diagnosed as having aggravated AS. Following re-initiation of adalimumab, symptoms did not improve and fever developed. On the basis of imaging studies, the patient was diagnosed as having an iliopsoas abscess and was successfully treated with intravenous antibiotics.