Advances and Controversies in Our Understanding of Guttate and Plaque Psoriasis.

Acute guttate psoriasis (AGP) is considered an uncommon variant of psoriasis (PsO), characterized as a widespread eruption of erythematous, psoriasiform papules, and plaques on the trunk, extremities, and scalp. Predisposing factors include a family history of PsO, variation in the main PsO susceptibility gene HLA-Cw*0602, and previous infection with viruses or acute ß-hemolytic Streptococcus A program focused on controversies and recent advances in understanding AGP was presented at the Group for Research and Assessment of Psoriasis and Psoriatic Arthritis (GRAPPA) 2022 annual meeting. Topics included an overview of clinical presentation and natural history, predisposing genetic and environmental factors, and the recent molecular profiling that supports classification of AGP as a form of PsO. Early molecular profiling studies using proteomic signatures have suggested similarities between AGP and contact dermatitis, but recent studies using gene expression profiling and gene set enrichment scores demonstrate that AGP is more similar to chronic PsO. The expression of regulatory immune pathways seen with AGP suggests potential for early and sustained remission if the disease is suppressed by targeted treatments. Published case reports documenting clinical improvement of AGP with biologics that antagonize interleukin (IL)-12/23, IL-23, and IL-17 support the role of the IL-23/IL-17 axis in AGP, similar to that in PsO. Data supporting the use of antibiotics and other therapeutic agents for AGP are lacking, and randomized controlled trials are needed. Trial design for AGP is challenged by the low incidence, tendency for spontaneous remission, lack of validated end points, and the need for long-term follow up.