Plain Language Summary: Ustekinumab-associated morphoea: systematic review of the literature and a real-world case

What was the purpose of this study?

Ustekinumab is a medicine used to treat immune-related conditions such as psoriasis, psoriatic arthritis, inflammatory bowel disease and, less commonly, Behçet disease. It works by blocking two immune proteins called IL-12 and IL-23, which play a role in inflammation. Ustekinumab is generally very safe but rare skin reactions may occur during treatment. One of these reactions is morphoea, a condition in which hard, thickened patches develop on the skin due to increased collagen. Morphoea is uncommon, and its connection to ustekinumab is not fully understood. The aim of this study was:

1. to review all previously published cases to understand how often morphoea develops following medication administration, what it looks like and how it is managed; and

2. to describe a new case of morphoea developing in a patient taking ustekinumab.

What did we find?

Our patient developed two firm, dark patches on the lower back 3 months after starting ustekinumab for Behçet disease. A skin biopsy confirmed morphoea. Ustekinumab was continued because it controlled the underlying disease well, and the skin lesions remained stable with topical treatment.

We also searched three major medical databases and found six earlier reported cases of morphoea linked to ustekinumab. In these reports, morphoea appeared after several months or years of treatment. Most patients had psoriasis or inflammatory bowel disease. The skin lesions were usually firm, discoloured plaques. When ustekinumab was stopped, the skin often improved. When the medicine was continued, the plaques sometimes worsened.

Why does this matter?

Although morphoea linked to ustekinumab is rare, recognising it early is important. This helps doctors decide whether to continue the medicine, switch to another treatment or add therapies for the skin. Understanding this reaction may also improve our knowledge of how the immune system influences skin inflammation and scarring. More research is needed to learn why this reaction occurs, who may be at higher risk and whether other medicines that block IL-23 may cause similar problems.

Article available at: https://doi.org/10.7573/dic.2025-11-1