A 45-year-old man with ankylosing spondylitis well controlled on infliximab for one year develops new thick scaly plaques over the scalp, palms and soles. He has no personal or family history of psoriasis. The most likely explanation is:

• A Cutaneous dissemination of latent tuberculosis
• B Paradoxical psoriasis induced by TNF-alpha blockade ✓
• C Secondary syphilis
• D Lichenoid drug eruption

Explanation

TNF-alpha inhibitors can induce de novo psoriasiform eruptions, thought to arise from unopposed type I interferon production by plasmacytoid dendritic cells once TNF is blocked. Palms, soles and scalp are typical sites. Management is usually continuation with a switch of agent rather than stopping all therapy. Secondary syphilis gives coppery red macules and palmoplantar involvement but not chronic thick plaques.

Reference: Fitzpatrick's Dermatology, 9th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.