Paraffin sections of 11 formalin-fixed trichilemthe genital HPVs (A); the epidermodysplasia verrucimomas were investigated for the presence of formis (EV)-associated HPVs (B); ungulate associated human papillomavirus (HPV) DNA by the polypapillomaviruses (C and D) and cutaneous HPVs (E) merase chain reaction (PCR) with the degener- [Chan et al., 1995]. Cross-hybridisation studies have ated consensus primer pairs. PCRs were conshown that the EV-associated HPV supergroup B can ducted with different annealing temperatures.
be divided into several subgroups of related genotypes When the annealing temperature was reduced [deVilliers 1989; Kremsdorf et al., 1984]. The EV-associfrom 55ЊC to 50ЊC, amplification products of the ated HPVs were found, in particular, on human skin, expected size were obtained for all 11 cases inin typical warts and squamous cell carcinomas.
vestigated. Determination of the HPV type was
The broad spectrum of epithelial hyperplasias which performed by cloning and sequencing of the amis induced by HPV displays a unique morphology with plification products.
papillomatosis and acanthosis, hypergranulosis and The sequence analysis of the eleven cloned vacuolated keratinocytes. Such morphological criteria amplicons gave the following data: based on seare found mainly in fresh verrucous lesions of the skin, quence comparison with published amino acid whereas older lesions have little or no koilocytes. The sequences, the best homology was found to architecture of the viral wart is, however, still present. epidermodysplasia verruciformis (EV)-associ-Trichilemmoma, first described by Headington and ated HPVs (supergroup B). In four specimens an
French in 1962 as benign neoplasm of the hair follicle, HPV type 23 related type was found; five speciexhibit many features of an advanced viral wart. These mens contained HPV sequences which did not tumours are non-specific clinically and generally apmatch with one of the known HPV types, but had pear as small, solitary, verrucous, domed, or smooththe closest homology to HPV types 15, 17, and surfaced papules on the face and neck. Multiple trichi-37. Three of the HPV variants which had not been lemmomas are a hallmark of Cowden's disease, a rare characterised, displayed identical sequences.
genodermatosis in which malignancies, mainly of the Two additional HPV amplification fragments disbreast and the thyroid, may develop. played 100% homology to HPV-6b.
Histologically, trichilemmomas are characterised as These results demonstrate, for the first time, sharply circumscribed, lobular epithelial proliferations the presence of HPV DNA in trichilemmomas.
in continuity with the epidermis, which exhibit a promi-The sequence data suggest that HPV variants or nent, clear cell component. Other features are periphtypes in trichilemmoma are members of the eral nuclear palisading, a thickened basement mem-EV-associated HPV supergroup B. J Med Virol brane, and varying degrees of hyperkeratosis and 51:119-125, 1997. ᮊ 1997 Wiley-Liss, Inc. parakeratosis [Ackermann, 1980]. Central follicular structures are often present. KEY WORDS: human papillomavirus; polymer-Whether trichilemmomas are true benign neoplasms ase chain reaction; epidermodysor virus-induced hyperplasias remains a current subject plasia verruciformis-associated of debate. Earlier studies using immunoperoxidase techniques did not reveal any evidence for papillomavi-HPVs rus infection [Penneys et al., 1984]. In the first study