Is Ki-67, keratin 16, involucrin, and filaggrin immunostaining sufficient to diagnose inflammatory linear verrucous epidermal nevus? A report of eight cases and a comparison with psoriasis vulgaris

Abstract

Inflammatory linear verrucous epidermal nevus and linear psoriasis are sometimes hard to differentiate clinically and pathologically. Although immunohistochemical expression of keratin 10 (K10), K16, Ki-67, and involucrin may be useful for differentiating both entities, these results have been reported in only a few cases. We collected data from 8 patients with inflammatory linear verrucous epidermal nevus, 11 with psoriasis vulgaris, and 8 healthy controls and evaluated immunohistochemical expression of Ki-67, K16, involucrin, and filaggrin among them. Ki-67 and K16 overexpression was similar in inflammatory linear verrucous epidermal nevus and psoriasis vulgaris compared with normal skin. Although staining for involucrin showed discontinuous expression in parakeratotic regions in 4 inflammatory linear verrucous epidermal nevus cases, it was continuous in the other 4 cases and in all psoriasis vulgaris cases. Filaggrin expression was present in hyperkera-totic regions but scarce in parakeratotic areas in both inflammatory linear verrucous epidermal nevus and psoriasis vulgaris. The immunostaining pattern of Ki-67, K16, involucrin, and filaggrin may be insufficient to discriminate inflammatory linear verrucous epidermal nevus from psoriasis vulgaris.