Photographs depicting the clinical phenotype. A. Dactylitis of the right fourth finger. B. Dactylitis of left fifth toe. C. Representative skin findings, here an annular plaque from right forearm characterized by erythema and overlying silvery scale, consistent with psoriasis. D. Scalp biopsy showing psoriasiform dermatitis, characterized by hyperkeratosis, parakeratosis, and neutrophils within the stratum corneum and spinous layer (hematoxylin and eosin, original magnification, 400×).