This 57-year-old man has a lifelong history of keratoderma involving the palms and soles. He has numerous, non-inflammatory, "cup-shaped" hyperkeratotic lesions, diffusely involving the palms and soles. Palmoplantar keratoderma has variable presentations and variable inheritance patterns. This patient had an isolated condition, without features of one of the syndromes, and no family history. The clinican had arsenic exposure on his differential. The histology here is fairly typical, showing hypergranulosis with overlying mounds of orthokeratosis.
At higher power of the same lesion, one can appreciate the epidermal acanthosis, hypergranulosis, and overlying hyperorthokeratosis. There is no cytologic atypia or inflammation.