Warts and molluscum contagiosum

HPV infection is highly specific for epidermis, especially extremities, palms, and soles, but also the scalp and mucosal surfaces such as the mouth, larynx, genital areas, and rectal mucosa. Some types of HPV have a predilection for infection in certain locations in the body (Table 26-1). For example, flat warts are seen mostly on the face and hands of children and are often caused by HPV types 3 and 10 (Fig. 26-1A). Common warts occur most often on the fingers and periungual skin and are commonly due to HPV types 2, 4, and 29 (Fig. 26-1B). Warts in immunosuppressed patients are caused by HPV type 8 and others (Fig. 26-1C).

Certain types of HPV infection have been associated with the development of malignancy. Although bowenoid papulosis is not considered a premalignancy, it may be associated with an increased risk of cervical cancer. Carcinomas of the conjunctiva, cornea, nasal cavities, oral cavity, esophagus, and plantar surface of the foot also have been reported in association with various types of HPV.

Carcinogenic wart types include the following: 16, 18, 31, 33, 35, 39, 45, 51, 52, 56, 58, 59, 68, and 69.

EV is a rare, inherited disorder in which cutaneous HPV infection is generalized and persistent. Most cases are autosomal recessive, but autosomal dominant and X-linked dominant forms are also reported. It is caused by mutations in either the EVER1 or EVER2 genes. The lesions are either flat warts or reddish-brown plaques, often developing in sun-exposed areas (Fig. 26-2A). Malignant change occurs in about 10% of cases, but metastasis is uncommon. HPV types 5 and 8 are most commonly seen in EV patients, although several other HPV types may also been seen.

Gül U, Kiliç A, Gönül M, et al: Clinical aspects of epidermodysplasia verruciformis and review of the literature, Int J Dermatol 46:1069–1072, 2007.

HPV infection occurs after exposure to humans or animals with HPV infection. The most common mode of transmission is through touch or contact from an individual infected with HPV, although HPV may also survive on inanimate objects for unknown amounts of time. Small abrasions or cracks in the skin of exposed persons allow the virus to penetrate. Such infection may commonly occur at a swimming pool, where chlorinated water and rough concrete surfaces may abrade the skin, or at other public places. Genital warts may be transmitted through sexual intercourse. People who work with meat, fish, and poultry also commonly have warts in the hand and forearm area, which are thought to be promoted through microinjuries sustained during processing of animals or fish, as well as from prolonged immersion of the skin in water.

Autoinoculation is another form of transmission. Periungual warts are often found in persons who have a habit of biting their cuticles, for example. Presumably the excoriated areas are more hospitable to virus, but spread of a single common wart is also possible. Flat warts in the beard area or on the legs may be spread by shaving.

Yes, especially if they are injured. Such injury may happen if the warts are in a location traumatized by shaving or scratching. This reaction is known as the Koebner phenomenon. (The Koebner reaction is also present in skin conditions that have no known viral cause, such as psoriasis and lichen planus.) Close approximation of two surfaces, where one surface is affected and the opposing surface is unaffected, is also associated with an increased likelihood of spreading (e.g., adjacent toe surfaces; Fig. 26-2B).