Answer to Image of the Month September 2014
Submitted by Poonam Panjwani and Rajalakshmi T
Inflammatory linear verrucous epidermal nevus (ILVEN)
The images show broad, well-circumscribed zones of parakeratosis alternating with areas of orthokeratosis. Underneath the parakeratosis, there is absence of granular layer while it is thickened below the orthokeratotic areas. The epidermis shows psoriasiform acanthosis. Spongiosis and dermal inflammation are variable. This patient had lesions present since childhood and they had a somewhat segmental distribution. Although common in lower extremities, they can be widespread or bilateral.
Pityriasis rubra pilaris shows ortho- and parakeratosis in both vertical and horizontal directions, constituting the checkerboard pattern. Hypergranulosis can be confluent. Axillary granular parakeratosis is usually confined to axillae and shows parakeratosis with retention of the granular layer underneath. ILVEN may mimic psoriasis both on clinical and histologic grounds. In psoriasis, the parakeratotic mounds are not as broad and keep the company of neutrophils.