These are multiple, small, yellowish, hyperkeratotic papules on the palms and soles, distinguished by a history of arsenic exposure.
A corn is a very localized, painful, cone-shaped area of hyperkeratosis over a bony prominence, unlike the diffuse thickening of a keratoderma.
These are a specific type of keratoderma, distinguished by their location as circumscribed, fibrous thickenings over the finger joints.
Palmoplantar psoriasis is characterized by well-demarcated, erythematous plaques with a thick, silvery scale, a more inflammatory picture than simple keratoderma.
