# Cutaneous Eruption in a Crohn’s Disease Patient Under Tumor Necrosis Alpha Inhibitor Treatment: A Rare Case of Syphilis

## TL;DR

A Crohn’s disease patient on anti-TNFα therapy developed a skin rash, which was diagnosed as syphilis and successfully treated with penicillin.

## Contribution

This case highlights the rare but important possibility of syphilis as a cutaneous manifestation in immunosuppressed patients.

## Key findings

- A 28-year-old Crohn’s patient on infliximab developed a painless, non-pruritic exanthema.
- Diagnosis of early secondary syphilis was confirmed via fluorescent treponemal antibodies-absorbed test.
- Treatment with benzathine penicillin G resolved the skin eruption within weeks.

## Abstract

Reaching a diagnosis of a cutaneous eruption in a Crohn’s disease (CD) patient treated with anti-tumor necrosis factor alpha (anti-TNFα) can be challenging. Differential diagnosis must include extra-intestinal manifestations of CD, adverse reactions to the therapy itself as well as infectious diseases with cutaneous manifestations. We report the case of a 28-year-old man on infliximab for Crohn’s colitis, who presented with painless, non-pruritic genital and body exanthema. After a thorough evaluation, early secondary syphilis was confirmed with a fluorescent treponemal antibodies-absorbed test. Intramuscular (IM) benzathine penicillin G 2.4 million units in a single dose was administered and clinical manifestations resolved completely within a couple of weeks.