Inflammatory Linear Verrucous Epidermal Nevus with Psoriasiform Histology

Abstract

Sir, Inflammatory linear verrucous epidermal nevus (ILVEN) is a rare disease characterized by pruritic, erythematous scaly lesions following Blaschko's lines. Clinically it may resemble psoriasis. ILVEN usually occurs in young adults, but has also been reported in childhood. Clinical criteria for ILVEN were defined by Altman and Mehregan[1] in 1971. Dupre and Cristol[2] described histopathological criteria for diagnosing ILVEN in 1977. A 21-year-old man presented with itchy, hyperkeratotic plaques distributed in a linear fashion over the right side of the body. The patient complained of having these lesions since he was 3 years of age. They were stable for a long period of time, but had progressed in size and severity over the past 4 years. On physical examination, patient had well-defined, hyper- and hypopigmented plaques over the trunk covered with thick scales with some areas of intervening normal skin. Lesions were distributed from just lateral and right to umbilicus [Figure 1], extending upwards, laterally, and posteriorly about the level of T12 vertebra. Similar lesions were also present over lateral [Figure 2] and posterior surface [Figure 3] of right arm extending from tip of shoulder to elbow joint in linear fashion. The patient also had hyperkeratotic plaques over the ulnar aspect of right hand and the medial aspect of right foot. The size of lesions varied from 0.2 × 0.2 cm to 3 × 1 cm with some lesions showing excoriation and eczematization. There was no evidence of any other skin lesions; and hair, nail, and mucosae were normal. Figure 1 Scaly hyperkeratotic plaques over trunk and right arm with some areas of intervening normal skin Figure 2 Scaly excoriated plaques over lateral surface of right arm and trunk Figure 3 Scaly plaques over posterior surface of right arm and right side of back Histopathology from lesion revealed regular psoriasiform hyperplasia of epidermis and dermal papillae [Figure 4]. Stratum corneum showed thickening, parakeratosis, and presence of Munroe's microabscesses. Granular layer was thinned or absent at places. There was a moderately dense perivascular mixed inflammatory infiltrate and the dermal papillae showed dilated capillaries with edema. Focal suprapapillary thinning of epidermis was evident. On the basis of histopathology, a diagnosis of nevoid psoriasis was made. The patient was prescribed psoralen + UVA (PUVA) therapy and oral methotrexate, with antihistamines and topical corticosteroids. He did not show satisfactory response to this treatment. The patient was then advised to have surgical excision of the lesions with skin grafting. He had satisfactory response to surgical excision. Figure 4 Psoriasiform hyperplasia of epidermis, hyperkeratosis, parakeratosis, Munro's microabscesses in stratum corneum, thinned granular layer, and dense perivascular mixed inflammatory infiltrate (H and E, ×45) There is considerable overlap between the two entities, that is, nevoid psoriasis and ILVEN. Nevoid or linear psoriasis is a rare variant of psoriasis, characterized by a linear unilateral distribution of the psoriatic lesions along the lines of Blaschko. It usually occurs in young adults, but has also been reported in childhood. It has been proposed that nevoid psoriasis may originate from migration of cells harboring a somatic mutation occurring at one of the many gene loci involved in psoriasis, along the lines of Blaschko during early embryogenesis. Psoriasiform lesions in a linear distribution (linear psoriasis) may also occur as a part of Koebner's phenomenon in the presence of lesions of psoriasis elsewhere. ILVEN can be invaded also by psoriasis as a result of koebnerization in presence of psoriatic lesions elsewhere. But the presence of psoriasiform lesions alone in a linear pattern or along the lines of Blaschko for a long duration points toward the diagnosis of either ILVEN with/without psoriasis, or nevoid psoriasis. ILVEN can be differentiated from nevoid psoriasis by duration, morphological distribution, pruritus, histopathology, and response to treatment. Further, immunohistopathological differentiations can be made to distinguish these two conditions.[3] There is lower level of keratin 10 expression in lesions of psoriasis, whereas in lesions of ILVEN without concomitant psoriasis, there is decreased Ki-67 positive nuclei, increased number of keratin 10 positive cells and HLA-DR expression as well as lower levels of cell surface expression markers of T-cell subsets, such as CD8, CD 45 RO, CD2, CD94, and CD161. Hofer hypothesized that like psoriasis, ILVEN may also represent segmental types 1 and 2 mutation.[4] He described four different groups of diseases to define precisely the correlation between ILVEN and psoriasis. The first group included case reports of ILVEN with or without concomitant psoriasis, who responded only a part to antipsoriatic treatment. The reason for not responding to antipsoriatic treatment was that the patients had preexisting epidermal nevus and pruritic inflammation developed later on.[4] Epidermal nevus, developing as a result of postzygotic mutation, may provide a fertile site for development of psoriasiform inflammation. In the second group, there were cases of ILVEN without concomitant psoriasis, who had good response to antipsoriatic treatment. The third group included linear psoriasis with psoriasis vulgaris, thus showing good response to treatment. In the fourth group, cases of linear psoriasis without concomitant psoriasis (i.e., nevoid psoriasis) were included and they responded well to antipsoriatic treatment. The second and fourth groups may represent segmental type 1 mutation and the third group may represent type 2 segmental mutation.[4] Our patient had onset of linear psoriasiform plaques in early childhood; the lesions had moderate itching and were present only on upper half of the body. The patient did not have lesions of psoriasis vulgaris elsewhere, which led us to believe that it was a case of ILVEN. But the histopathology of a biopsied lesion was suggestive of psoriasis and the response to antipsoriatic treatment was unsatisfactory in our patient. Thus we categorize this case in the first group of Hofer, that is, ILVEN with concomitant psoriasis and no response to treatment. The patient had satisfactory response to surgical excision. We report this interesting case as only few cases[5 6 7 8 9 10] are reported in the literature and also because, despite of having histopathological features of psoriasis, there was no response to antipsoriatic treatment but to surgical excision.