Human papillomavirus (HPV) induced epithelial cell proliferation is responsible for a broad range of lesions. Treatment of such lesions is characterized by a high relapse rate. Four patients are described who were treated locally with cidofovir (cream 1% or injection of 2.5 mg/ml solution) for multi-treated relapsing HPV-associated lesions. Three of the four patients had a complete response. The fourth patient showed a clinical response in the first cycle of treatment, but new lesions appeared during four successive cycles of cidofovir.

We used immunohistochemistry to study Langerhans cells (LCs) and the composition of the dermal inflammatory infiltrate both in normal skin and in biopsies from various benign and malignant pigment-cell lesions. In normal skin and most benign pigment-cell lesions, epidermal LCs are regularly distributed. OKT6-Positive cells outnumber the OKIa-positive cells. The inconspicuous dermal infiltrate studied in these biopsies was composed of helper and suppressor/cytotoxic T cells and some dermal LCs. More epidermal LCs with an abnormal cytologic presentation were found in a halo naevus and in the radial growth part of primary malignant melanomas. This finding was associated with a dermal infiltrate composed of suppressor/cytotoxic T cells, suggesting a defense mechanism of the host towards abnormal melanocytes. Epidermal LCs were rare in the central part of the biopsies which showed a primary malignant melanoma in its vertical growth. A dermal inflammatory infiltrate was absent in that area. These findings are interpreted as the morphologic expression of a damaged immune system.

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