palmoplantar keratoderma There are often characteristic islands of sparing ( Fig 70.8 ) It is most often confused with psoriasis, which it can closely resemble, but PRP lesions lack the overlying silvery scale of psoriasis PRP is often idiopathic and sporadic in its occurrence PRP can occur as a postinfectious process (most commonly streptococcal and occasionally HIV), as an adverse drug reaction, and in adults, as a paraneoplastic phenomenon associated with a variety of malignancies The condition has also been associated with CARD mutations and autosomal dominant inheritance (early-onset form) Long-term treatments include use of emollients, topical corticosteroids, topical retinoids, vitamin D analogs, topical calcineurin inhibitors, and systemic agents such as phototherapy and biologic agents (infliximab, ustekinumab, etanercept, adalimumab)