Histological study of necrolytic acral erythema.

Described in 1996, necrolytic acral erythema remains the sole diagnostic cutaneous marker for hepatitis C virus infection. To date only eight cases have been described in literature, a fact that makes full histological description and appreciation of the disease process inadequate. Thirty necrolytic acral erythema cases were biopsied and detailed histological description was performed by three separate dermatopathologists who were blinded as to clinical presentation. Clinicopathological correlation was used to evaluate the disease progress. In the early stage, there is moderate regular acanthosis with variable spongiosis and inflammation, progressing to a picture resembling nummular eczema. In its fully evolved form, necrolytic acral erythema shows psoriasiform epidermal hyperplasia with marked papillomatosis. Associated findings include parakeratosis, focal hypergranulosis, subcorneal pustule, epidermal pallor, necrotic keratinocytes, which sometimes become confluent in the upper epidermis and/or track along the acrosyringia, vascular ectasia and papillary dermal inflammation. Late stage samples display some remaining acanthosis with variable inflammation. Pigment incontinence is seen in all stages.