New-onset psoriatic palmoplantaris pustulosis following infliximab therapy: a class effect?

Reports of induction or exacerbation of psoriatic palmoplantaris pustulosis (PPPP) after anti-tumor necrosis factor-alpha (TNF-alpha) treatment are few. We describe 2 new cases of PPPP induced by infliximab. In 1999, a total of 442 patients in our department received anti-TNF-alpha treatment for a variety of chronic rheumatic conditions and were regularly followed. Medical records for 166 given infliximab were retrospectively reviewed for disease [rheumatoid arthritis (RA), spondylarthropathies (SpA) including psoriatic arthritis], disease duration, clinical characteristics, skin side-effects, and use of other potentially relevant medications. PPPP was observed in 2 patients treated with infliximab for symmetrical rheumatoid factor-positive RA; the patients had no personal or family history of psoriasis. In both cases, pustulosis appeared after several months of infliximab administration. There was no clinical, biological, or radiological evidence to support a diagnosis of psoriatic SpA. Both patients fulfilled ACR criteria for RA, and there was no reason to suspect previously unidentified psoriasis. Comorbid RA and psoriasis are unusual, and our patients exhibited a clear link between anti-TNF-alpha administration and cutaneous lesions, suggesting a direct effect in both cases. The 28 published cases of PPPP induced by anti-TNF-alpha treatment report lesions that tend towards pustulosis and palmoplantar localization. The mechanisms involved remain elusive. Disappearance of lesions in our second patient when switched to a soluble receptor suggests a molecule-specific side effect, while the literature describing variable reaction to switching anti-TNF agents, and/or their discontinuation and reintroduction, indicates otherwise. Given the rarity of this side effect, its elucidation will require systematic study.