Pityriasis rubra pilaris with symmetric polyarthritis and lymphadenopathy

Pityriasis rubra pilaris (PRP) is a rare, inflammatory cutaneous disorder of unknown aetiology, and its association with inflammatory joint disease has not been well established. The lack of definitive evidence or clear guidelines makes PRP treatment difficult. Our patient presented with multiple large non-melanoma skin cancers (NMSCs) and a progressive cutaneous eruption consistent with PRP. NMSCs on presentation were found to be five basal cell carcinomas (BCCs), one squamous cell carcinoma and one invasive carcinoma with basaloid and squamous differentiation to skeletal muscle requiring radiation. His course was complicated by arthritis and reactive lymphadenopathy. Our patient saw slow improvement in his rash after treatment with ixekizumab and multiple Mohs surgeries for removal of his BCCs with decreased pruritus, erythema and hyperkeratosis. PRP-associated arthritis is a rare component of the primarily dermatologic disorder, and it is important for clinicians to be aware of this association to adequately address joint manifestations.