Author: Assoc Prof Patrick Emanuel, Dermatopathologist, Auckland, New Zealand, 2013.
Verruca plana (plane warts) are typically associated with human papillomavirus (HPV) types 2, 3, and 10. HPV 5 may be seen in human immunodeficiency virus (HIV)-positive patients.
Histology of verruca plana
Sections show orthokeratosis, mild papillomatosis, and mild acanthosis (figure 1). There is usually no or minimal parakeratosis. The dermis is normal. The upper epidermis shows hypergranulosis and numerous koilocytes (figures 2, 3). Regressing lesions may show a lymphocytic response and keratinocyteapoptosis.