Human papillomavirus: disease and laboratory diagnosis.

Human papillomaviruses (HPVs) can be classified biologically or phylogenetically into cutaneous or mucosal types. Cutaneous papillomaviruses produce benign skin tumours (warts) which occur commonly on the hands, face and feet. They spread readily among children and young adults during recreational activities. Laboratory diagnosis of skin warts is usually unnecessary as they can be distinguished morphologically. Large numbers of cutaneous warts may develop in patients with epidermodysplasia verruciformis, a rare familial disorder. Exposure to sunlight sometimes causes these lesions to progress to skin cancer. HPVs are the most common sexually transmitted viruses, infecting both men and women. They can be transmitted from the vagina at birth, and may cause recurrent respiratory papillomas in childhood or adult life. Genital infection usually clears within a few months, but may persist in some individuals. HPV has been firmly linked with cancer of the cervix, and is also associated with cancer at other mucosal sites. The distribution of genital HPV types varies and is related to the degree of cervical dysplasia present. HPV types 6 and 11 are frequently found in sexually active adults, and are associated with low-grade squamous epithelial lesions. HPV types 16, 18, 31 and 45 are found less frequently, and are associated with progression to invasive cancer. Commercial dot blot hybridisation and DNA-RNA hybridcapture assays are available for laboratory diagnosis of genital HPV infection. The polymerase chain reaction (PCR) is used for diagnosis and epidemiological surveys. Detection of particular HPV types could be useful in the diagnosis and management of cervical cancer in older women, and for resolving equivocal (borderline) cytology. HPV assays, which can distinguish between high-grade and low-grade disease, may also have a role in routine cervical screening.