K17 is a stimulator of psoriatic T cells (Th‐17) and producer of specific cytokines (IL‐17) which in turn stimulate K17, again leading to an “autoimmune feedback loop.”36, 37 This “feedback loop” might explain the persistent palmar hyperkeratosis at the same location of this clinical phenotype. The gene discussed is IL17A; the disease is Hyperkeratosis.