Two anatomoclinical types of warts with plantar localization: specific cytopathogenic effects of papillomavirus. Type I (HPV-1) and type 2 (HPV-2).

In this study, the clinical and histopathological aspects of 50 plantar warts are reported in relation to the type of papillomavirus present in the lesions, as detected by immunofluorescence tests, using specific guinea pig fluorescein-labelled IgG. Warts of plantar localization are not caused by the same human papillomavirus (HPV) since they are found to be associated with both HPV type 1 (HPV-1) and HPV type 2 (HPV-2). HPV-1 is always associated with deep and painful plantar warts (myrmecia), whereas HPV-2 is found to be associated with superficial, painless plantar warts (vulgaris or often mosaic type). Histologically, these two types of plantar warts are quite different. In myrmecia (HPV-1), characterized by an endophytic growth, large eosinophilic, keratohyaline-like granules are observed in the cytoplasm and nucleus of infected, often vacuolated cells. These granules appear early in stratum spinosum and are very numerous in stratum granulosum. In the mosaic type (HPV-2), the histopathological aspect is not different from that of common warts; these lesions have an exophytic growth and are characterized by foci of clear vacuolized cells which are found in stratum granulosum. Their cytoplasm contains round, basophilic keratohyalin granules which often have a heterogenous aspect. These differences are observed in other localizations of morphologically related warts associated with HPV-1 and HPV-2 and seem to be related to a specific cytopathogenic effect of HPV-1 an HPV-2 in human papillomas.