Images of Memorable Cases: Case 22 This 27-year-old man complained of pain and swelling in his right knee and left index finger of one month’s duration. Three weeks before onset of these complaints, he had had a five-day bout of diarrhea. Shortly before admission, he noticed a painless rash on his glans penis. 22. Reactive arthritis Formerly called Reiter’s syndrome. The image shows balanitis circinata and fusiform swelling of the proximal interphalangeal joint, both features of this sterile, inflammatory arthropathy. Infections of the urinary tract or gut typically trigger this disorder.