Sir,Recent studies have identified various types of human papillomavirus (HPV) in Bowen's disease (BD) on the hands and feet, especially at periungual and subungual sites (1, 2). BD represents a squamous cell carcinoma in situ. HPV 16 and other 'high risk' types have frequently been identified as in genital BD. Only two cases of BD on the web-spaces of the foot have been reported (3, 4). We describe a case of BD arising in the web-space of the foot associated with HPV 16.
CASE REPORTA 33-year-old Japanese man had observed a brownish macule on his left foot for 1 year. He had previously been treated for tinea pedis with topical antifungal agents. Physical examination revealed a brownish, relatively well demarcated macule, 763 mm in diameter, in the web-space between the third and fourth toes of his left foot (Fig. 1a). A skin-coloured, keratotic papule was observed adjacent to the brownish macule. He had no history of genital disorders such as bowenoid papulosis or condyloma acuminatum. Histopathological examination of a skin biopsy revealed proliferation of irregularly arranged atypical keratinocytes throughout the epidermis, hyperkeratosis with dyskeratotic, clumping cells and mitotic figures (Fig. 1b). A diagnosis of BD was made. FontanaMasson staining showed an increased amount of melanin in the basal layer and numerous pigment-filled dendritic melanocytes in the lesion. Melanophages were also prominent in the upper dermis. The HPV capsid antigen was detected by immunohistochemical analysis (K1H8, Dako, Kyoto, Japan). Southern blot hybridization was employed to detect HPV DNA and determine the HPV genotype. The cleavage patterns of the lesion were similar to those of prototype HPV 16 (Fig. 1c). The lesion was surgically removed and no relapse was observed after 1 year.
DISCUSSIONOur case is clinically characterized by a very small, brownish and keratotic macule on the web-space of the patient's left foot. Histopathological findings were compatible with those of BD. Pigmentation was caused by the presence of pigment-filled melanocytes, a large amount of melanin in the basal layer and prominent melanophages in the upper dermis. HPV 16 DNA was identified in the lesion.Over 90 HPV genotypes have been characterized. HPV 16 was first found in extragenital BD in 1983 (5), and subsequently also in BD of the hands and feet (2). a b c Fig. 1. (a) Well-demarcated pigmented macule in the web-space between the third and fourth toes of the left foot. (b) Proliferated atypical keratinocytes throughout the epidermis, with hyperkeratosis, dyskeratotic cells, clumping cells and mitotic figures (haematoxylineosin stain; original magnification 6100). (c) Detection of human papillomavirus 16 DNA in the lesion by Southern blot hybridization. The DNA was digested with several restriction enzymes: PstI (P), BanI (B) and MspI (M).