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Viral Infections
Human Papillomavirus and Disorders of the Skin
a report by
Sherrif F Ibrahim, MD, PhD and Mary Gail Mercurio, MD
Department of Dermatology, University of Rochester
Human papillomaviruses (HPVs) are ubiquitous viruses that produce While all HPV strains infect squamous epithelial tissue, different types have
epithelial neoplasms of the skin and mucous membranes. While a predilection for specific areas of the body. Clinically, they are grouped
papillomaviruses in general are known to affect a wide range of vertebrate according to their observed type of manifestation—mucosal, cutaneous,
species, each type displays remarkable species specificity because human and epidermodysplasia verruciformis—and phylogenetic analyses correlate
keratinocytes are the only cells that HPV can infect and provide the only well with these subtypes.
5
The majority of human infections with HPV are
known reservoir for the virus. Over 120 types of HPV have been isolated,
1
asymptomatic, with the most common manifestation of infection being
and infections with different strains are linked to a variety of skin benign cutaneous and genital warts.
4
However, much attention has
manifestations from common warts to cancer. As such, the study of high- been devoted to the study of HPV and its role in the development of
risk HPV types and their associated conditions has served as a model for cutaneous malignancies.
viral oncogenesis.
Benign Human Papillomavirus-related Skin Diseases
All types of HPV are small double-stranded DNA viruses with a circular HPV infection results in a variety of benign skin growths and is strongly
genome of approximately 8,000 base pairs and a life-cycle tightly regulated implicated in the development of certain anogenital cancers. A
by keratinocyte differentiation.
2
With minor trauma to the skin surface, virions combination of factors including HPV type, host response, and
enter the body and infect the basal layer of the epithelium where dividing environmental stimuli ultimately determines the course of a given lesion.
precursor skin cells reside. However, many critical viral genes are not activated The most commonly seen lesion is the common wart, or verruca vulgaris,
until differentiation occurs and keratinocytes begin an upward progression which can be caused by several low-risk HPV types and can occur anywhere
through the epidermis.
3
Genes encoding viral capsid proteins are only on the skin surface. Other types of benign lesions include plantar warts,
transcribed as keratinocytes approach the outer surface of the skin, die, and flat warts, butcher’s warts (common in people who handle meat and fish),
are sloughed off into the environment, leaving fully functional viral particles in and genital warts. Although most infections are subclinical, lesions can
an optimal position for transmission to other hosts and body parts. This aspect occur anywhere from a few weeks to several years after initial infection.
4
of HPV has made it a difficult target to study, as the need for terminally Studies of HPV DNA from different cells within a given wart have revealed
differentiated cells to propagate precludes the ability for HPV to be grown in the same genetic make-up, which implies that the lesion arises from a
tissue culture since terminally differentiated cells do not divide.
4
single infected basal keratinocyte.
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HPV is considered the most common sexually transmitted disease, with a
Sherrif F Ibrahim, MD, PhD, is a Resident in Dermatology at the
University of Rochester School of Medicine. His research interests
prevalence as high as 60% among sexually active women.
7
Recent studies
concern the development of new genomic and proteomic have demonstrated that sexual intercourse with just one person confers
approaches to the study of oncogenesis and stem cell biology in
increased risk for infection.
8
Condyloma accuminata, or genital warts, are
the skin. Dr Ibrahim received his MD and PhD from the
University of Washington School of Medicine, and completed his
caused by low-risk HPV types 6 and 11 in 90% of cases and are primarily
graduate work in the Department of Molecular Biotechnology at transmitted by sexual contact. Accordingly, there is a correlation between
the Institute for Systems Biology, Seattle.
HPV infection and indicators of sexual activity such as the number of
lifetime sexual partners and age of initial sexual intercourse.
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In women,
Mary Gail Mercurio, MD, is an Associate Professor of lesions can occur anywhere on the vulva, vaginal introitus, cervix, perineum,
Dermatology at the University of Rochester School of Medicine
suprapubic, or peri-anal regions. In men, the penis, perineum, subrapubic,
and Dentistry. She trained in dermatology and was Chief
Resident at the University Hospitals of Cleveland. She has
and peri-anal areas are commonly affected, keeping in mind that subclinical
published several articles and book chapters on a variety of
infections of the anogenital area are exceedingly common in both sexes.
topics in dermatology, and has particular clinical expertise in the
Similarly, multiple infection sites are frequently seen, and their identification
management of women with genital skin disorders. Dr Mercurio
completed an internship in internal medicine at the Strong
can be enhanced by the application of 3–5% acetic acid to display so-called
Memorial Hospital of the University of Rochester, where she also
acetowhite changes. Grossly visible lesions tend to be exophytic with a
attended medical school and was a member of the Alpha Omega
rough, verrucous or cauliflower-like surface. These growths can be easily
Alpha honor society.
irritated and friable, causing bleeding or secondary infection. If left
E: marygail_mercurio@urmc.rochester.edu
untreated, warts can spontaneously regress, persist in a constant form, or
continue to increase in size. Management of warts can be challenging and
40 © TOUCH BRIEFINGS 2008
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