Development of Drug-Induced Inverse Psoriasis in a Patient with Crohn's Disease.

Crohn's disease is difficult to manage and often requires multiple medications. While these drugs vastly improve quality of life, physicians must monitor for adverse events. We report a case of a flare of inverse psoriasis after 15 months of treatment with ustekinumab. This is the third reported case of a flare of drug-induced psoriasis with ustekinumab, and it is the first reported case with an inverse presentation; however, the clinical picture is confounded by concomitant use of hydroxychloroquine. Inverse psoriasis is a rare variant of drug-induced psoriasis of which physicians must be cognizant while treating patients with Crohn's disease.