A 24 y.o. male with HIV comes in with bright red blood per rectum and a swollen painful knee.

What would be a unifying diagnosis?

hint: there is marked thickening of the rectal wall and lymphadenopathy of the inferior mesenteric chain. Arthrocentesis revealed a WBC of 48,926.

Our patient had chlamydial proctitis with reactive arthritis.

The old term for this reactive arthritis was Reiter’s syndrome but this is no longer used.  As originally described, Reiter’s syndrome or reactive arthritis involved urethritis, conjunctivitis and arthritis.

About 80% of people with reactive arthritis have the HLA-B27 gene. Only 6% of people who do not have the syndrome have the HLA-B27 gene. Bacterial triggers, such as salmonella, shigella, Yersinia, and Campylobacter have been reported. . Sexually transmitted infection (STI) triggers, such as chlamydia and gonrorrhea are also common.. The most requently reported  genital infection is Chlamydia trachomatis in 2/3 of the cases and  Neisseria gonorrhea in  16%. 

Because the HLA-B27 gene is often present, there may be a personal or family history of ankylosing spondylitis, psoriatic arthritis or inflammatory bowel arthritis.

Other manifestatiions of reactive arthritis are listed below.

A psoriasis like rash can be a manifestation of reactive arthritis.

The distribution of joint pain at the knees, ankles and feet is described. Lover’s heel refers to  gonococcal tenosynovitis of the Achilles tendon.

in reactive achilles enthesitis Kager’s triangle is often obliterated because of inflammation

Most cases of reactive arthritis  are self-limiting and resolve in 4-6 months but 50% have recurrent episodes and 17% have chronic symptoms. It is controversial whether treatment of the STI alters the course of the arthritis which may result.  Our patient has persistent joint symptoms although his rectal bleeding has resolved.

Carlin E. Flew S. Sexually acquired reactive arthritis. 2016 Clin Med (Lond). Apr;16(2):193-196. Doi:10.7861/clinmedicine 16-2-193.

Keat A, Maini R, Pegrum, et al. The clinical features and HLA associations of reactive arthritis associated with non-gonoccal urethritis. QJM 1979;48:323-42

Colmegna I, Cuchacovich R, Espinonza L. HLA-B27-associated reactive arthritis: pathogenetic and clinical consideration. Clin Microbiol Rev 2004;17:348-69.

Jin Lee K, Hwan Shin D, et al. chlamydial proctitis in a young man who has sex with men misdiagnosed as inflammatory bowel disease. 2015. Chonnam Med J. Dec;51(3):130-1