Palmoplantar psoriasis
Pustular psoriatic disease can be localized to the hand and/or feet only, or can co-occur with generalized pustular disease, just as palmoplantar psoriasis can be localized to the hands and/or feet or, more commonly, can co-occur with widespread plaque psoriasis. Research has shown, Dr. Hawkes said, that with both types of acral disease, many patients have or have had plaque psoriasis outside of acral sites.
The nomenclature and acronyms for palmoplantar psoriatic disease have complicated patient education, communication, and research, Dr. Hawkes said. Does PPP refer to palmoplantar psoriasis, or palmoplantar pustulosis, for instance? What is the difference between palmoplantar pustulosis (coined PPP) and palmoplantar pustular psoriasis (referred to as PPPP)?
What if disease is only on the hands, only on the feet, or only on the backs of the hands? And at what point is disease not classified as palmoplantar psoriasis, but plaque psoriasis with involvement of the hands and feet? Inconsistencies and lack of clarification lead to “confusing” literature, he said.
Heterogeneity in populations across trials resulting from “inconsistent categorization and phenotype inclusion” may partly account for the recalcitrance to treatment reported in the literature, he said. Misdiagnosis as psoriasis in cases of localized disease (confusion with eczema, for instance), and the fact that hands and feet are subject to increased trauma and injury, compared with non-acral sites, are also at play.
Trials may also allow insufficient time for improvement, compared with non-acral sites. “What we’ve learned about the hands and feet is that it takes a much longer time for disease to improve,” Dr. Hawkes said, so primary endpoints must take this into account.
There is unique immunologic signaling in palmoplantar disease that differs from the predominant signaling in traditional plaque psoriasis, he emphasized, and “mixed immunophenotypes” that need to be unraveled.
Dr. Hawkes disclosed ties with AbbVie, Arcutis, Bristol-Myers Squibb, Boehringer Ingelheim, Janssen, LEO, Lilly, Novartis, Pfizer, Regeneron, Sanofi, Sun Pharma, and UCB. Dr. Noe disclosed ties to Bristol-Myers Squibb and Boehringer Ingelheim.