Background: We studied biopsy material from four patients with inflammatory linear verrucous epidermal nevi (ILVEN) that had a psoriasiform appearance histologically and seven cases of linear epidermal nevi (LEN). Of the seven LEN, five showed hyperkeratosis, papillomatosis, and varying degrees of acanthosis; two had features of epidermolytic hyperkeratosis. Because these lesions have distinctive histologic patterns, we wanted to determine whether we could also demonstrate a distinctive pattern of immunohistochemical markers.

Methods: On all 11 cases we performed immunohistochemical stains for PCNA, factor XI-Ila, MAC-387, UCHL-1, and OPD-4. In addition, on one case of ILVEN we performed ICAM-1, ELAM-1, and HLA-DR stains.

Results: The pattern of staining of PCNA, factor XIIIa, MAC-387, UCHL-1, and OPD-4 was distinctly different in ILVEN and LEN. Staining for ICAM-1 was present on keratinocytes, and ELAM-1 was present on endothelial cells in two cases of ILVEN. HLA-DR in these same two cases of ILVEN stained mainly dendritic cells in the epidermis.

Conclusion: The different pattern of staining of PCNA, factor XIIIa, MAC-387, UCHL-1, and OPD-4 in LEN and ILVEN indicates a different mechanism of growth dysregulation. Stains for ICAM-1, ELAM-1, and HLA-DR in ILVEN suggest that an inability to down-regulate the inflammatory infiltrate may be important in the growth dysregulation in ILVEN. In addition, the onset of ILVEN at the time of HIV-1 infection in one patient suggests that HIV-1 infection may be one of many factors that initiates ILVEN in a susceptible person.