Shared and persistent asymptomatic cutaneous human papillomavirus infections in healthy skin

T Cell Surveillance during Cutaneous Viral Infections

The skin is a complex tissue that provides a strong physical barrier against invading pathogens. Despite this, many viruses can access the skin and successfully replicate in either the epidermal keratinocytes or dermal immune cells. In this review, we provide an overview of the antiviral T cell biology responding to cutaneous viral infections and how these responses differ depending on the cellular targets of infection. Much of our mechanistic understanding of T cell surveillance of cutaneous infection has been gained from murine models of poxvirus and herpesvirus infection. However, we also discuss other viral infections, including flaviviruses and papillomaviruses, in which the cutaneous T cell response has been less extensively studied. In addition to the mechanisms of successful T cell control of cutaneous viral infection, we highlight knowledge gaps and future directions with possible impact on human health.

Prevention and Treatment of HPV-Induced Skin Tumors

Non-melanoma skin cancer (NMSC) is the most common cancer in humans with increasing incidence. Meanwhile, a growing body of evidence has provided a link between skin infections with HPV of the genus beta (betaHPV) and the development of cutaneous squamous cell carcinomas (cSCCs). Based on this association, the development of vaccines against betaHPV has become an important research topic. This review summarizes the current advances in prophylactic and therapeutic betaHPV vaccines, including progresses made in preclinical testing and clinical trials.

Human papillomaviruses: diversity, infection and host interactions

Human papillomaviruses (HPVs) are an ancient and highly successful group of viruses that have co-evolved with their host to replicate in specific anatomical niches of the stratified epithelia. They replicate persistently in dividing cells, hijack key host cellular processes to manipulate the cellular environment and escape immune detection, and produce virions in terminally differentiated cells that are shed from the host. Some HPVs cause benign, proliferative lesions on the skin and mucosa, and others are associated with the development of cancer. However, most HPVs cause infections that are asymptomatic and inapparent unless the immune system becomes compromised. To date, the genomes of almost 450 distinct HPV types have been isolated and sequenced. In this Review, I explore the diversity, evolution, infectious cycle, host interactions and disease association of HPVs.

Development of a β-HPV vaccine: Updates on an emerging frontier of skin cancer prevention

Human papillomaviruses (HPVs) are small, non-enveloped, doublestranded DNA viruses. Over 200 subtypes of HPV have been identified, organized into five major genera. β-HPVs are a group of approximately 50 HPV subtypes that preferentially infect cutaneous sites. While α-HPVs are primarily responsible for genital lesions and mucosal cancers, growing evidence has established an association between β-HPVs and the development of cutaneous squamous cell carcinomas. Given this association, the development of a vaccine against β-HPVs has become an important topic of research; however, currently licensed vaccines only provide coverage for genital HPVs, leaving β-HPV infections and their associated skin cancers unaddressed. In this review, we summarize the current advances in β-HPV vaccine development, including progress made in preclinical testing and limited clinical data. We also discuss novel findings in the viral pathomechanisms involved in β-HPV cutaneous tumorigenesis that may play a large role in future vaccine development. We hope that synthesizing the available data and advances surrounding β- HPV vaccine development will not only lead to increased dedication to vaccine development, but also heightened awareness of a future vaccine among clinicians and the public.

Mucosal and Cutaneous Human Papillomavirus Infections and Cancer Biology

Papillomaviridae is a family of small non-enveloped icosahedral viruses with double-stranded circular DNA. More than 200 different human papillomaviruses (HPVs) have been listed so far. Based on epidemiological data, a subgroup of alphapapillomaviruses (alpha HPVs) was referred to as high-risk (HR) HPV types. HR HPVs are the etiological agents of anogenital cancer and a subset of head and neck cancers. The cutaneous HPV types, mainly from beta and gamma genera, are widely present on the surface of the skin in the general population. However, there is growing evidence of an etiological role of betapapillomaviruses (beta HPVs) in non-melanoma skin cancer (NMSC), together with ultraviolet (UV) radiation. Studies performed on mucosal HR HPV types, such as 16 and 18, showed that both oncoproteins E6 and E7 play a key role in cervical cancer by altering pathways involved in the host immune response to establish a persistent infection and by promoting cellular transformation. Continuous expression of E6 and E7 of mucosal HR HPV types is essential to initiate and to maintain the cellular transformation process, whereas expression of E6 and E7 of cutaneous HPV types is not required for the maintenance of the skin cancer phenotype. Beta HPV types appear to play a role in the initiation of skin carcinogenesis, by exacerbating the accumulation of UV radiation-induced DNA breaks and somatic mutations (the hit-and-run mechanism), and they would therefore act as facilitators rather than direct actors in NMSC. In this review, the natural history of HPV infection and the transforming properties of various HPV genera will be described, with a particular focus on describing the state of knowledge about the role of cutaneous HPV types in NMSC.

Beta Human Papillomavirus and Associated Diseases

The cutaneous human papillomavirus (HPV), mostly from β- and γ-HPV genus, is ubiquitously distributed throughout the human body and may be part of the commensal flora. The association of β-HPVs and cutaneous squamous cell carcinoma (cSCC) development was initially reported in patients with the rare genetic disorder Epidermodysplasia verruciformis. Likewise, immunosuppressed organ transplant recipients have an increased susceptibility to β-HPV infections in the skin as well as to cSCC development. Although ultraviolet radiation (UVR) is the main risk factor of cSCC, experimental data points toward β-HPVs as co-carcinogens, which appear to be required solely at early stages of skin carcinogenesis by facilitating the accumulation of UVR-induced DNA mutations. Several epidemiological studies relying on different biomarkers of β-HPV infections have also been conducted in immunocompetent individuals to access their association with cSCC development. Additionally, in vivo and in vitro studies are presenting cumulative evidence that E6 and E7 proteins from specific β-HPVs exhibit transforming activities and may collaborate with different environmental factors in promoting carcinogenesis. Nevertheless, further research is crucial to better understand the pathological implications of the broad distribution of these HPVs.

Cutaneous HPV and alpha-mucosal 9-valent HPV sero-status associations

Seroepidemiology of human papillomaviruses (HPV) among men is poorly understood. We examined the association between seropositivity to cutaneous HPV and 9-valent HPV (9vHPV) types. Six hundred men were randomly selected from the HPV Infection in Men (HIM) Study. Archived serum specimens were tested for antibodies against 9vHPV types [low-risk (6/11) and high-risk (16/18/31/33/45/52/58)], and 14 cutaneous types, including β-types 5/8/12/14/17/22/23/24/38/47, α-type-27, γ-type-4, µ-type-1, and ν-type-41, using a GST L1-based multiplex serology assay. Risk factor data were collected through questionnaires. Logistic regression was used to evaluate associations between mucosal and cutaneous HPV types. Approximately 21% of men were positive for ≥ 1 cutaneous HPV type, and ≥ 1 nine-valent HPV vaccine type at the same time. Men who were seropositive for any-cutaneous HPV were nearly twice as likely to be seropositive for 9vHPV (adjusted odds ratio (AOR) = 1.97, 95% confidence interval (CI): 1.30-2.99), high-risk (AOR = 1.83; 95% CI: 1.04-3.20), low-risk (AOR = 1.92; 95% CI: 1.16-3.18), and four-valent, 4vHPV, (AOR = 2.01; 95% CI: 1.25-3.21). Type-specific cutaneous HPV seropositivity (types: 8/14/17/23/38/27/4/1) was also positively associated with seropositivity to 9vHPV, high-risk, and low-risk categories. These data indicate that exposure to cutaneous HPV and 9vHPV types is common. Future longitudinal studies are needed to assess the temporality of these associations.

Loss of Genome Fidelity: Beta HPVs and the DNA Damage Response

While the role of genus alpha human papillomaviruses in the tumorigenesis and tumor maintenance of anogenital and oropharyngeal cancers is well-established, the role of genus beta human papilloviruses (β-HPVs) in non-melanoma skin cancers (NMSCs) is less certain. Persistent β-HPV infections cause NMSCs in sun-exposed skin of people with a rare genetic disorder, epidermodysplasia verruciformis. However, β-HPV infections in people without epidermodysplasia verruciformis are typically transient. Further, β-HPV gene expression is not necessary for tumor maintenance in the general population as on average there is fewer than one copy of the β-HPV genome per cell in NMSC tumor biopsies. Cell culture, epidemiological, and mouse model experiments support a role for β-HPV infections in the initiation of NMSCs through a "hit and run" mechanism. The virus is hypothesized to act as a cofactor, augmenting the genome destabilizing effects of UV. Supporting this idea, two β-HPV proteins (β-HPV E6 and E7) disrupt the cellular response to UV exposure and other genome destabilizing events by abrogating DNA repair and deregulating cell cycle progression. The aberrant damage response increases the likelihood of oncogenic mutations capable of driving tumorigenesis independent of a sustained β-HPV infection or continued viral protein expression. This review summarizes what is currently known about the deleterious effects of β-HPV on genome maintenance in the context of the virus's putative role in NMSC initiation.

Natural history of human papillomavirus infection of sun-exposed healthy skin of immunocompetent individuals over three climatic seasons and identification of HPV209, a novel betapapillomavirus

We present the first longitudinal study reporting the natural history of human papillomavirus (HPV) infection in sun-exposed skin of healthy individuals living in a geographical area in which solar UV radiation is influenced by the ozone content of the atmosphere. During three climatic seasons, skin swab samples were obtained from 78 healthy individuals and the prevalence of cutaneous HPVs was assessed with broad-spectrum FAP and CUT primers and determined at 54, 45 and 47 % in spring, summer and winter, respectively. Frequencies of mixed HPV infections were significantly higher in spring with respect to summer and winter (P=0.02). Seventy-one different HPV types/putative types were identified. While 62 volunteers were HPV-infected in at least one season, 23 had persistent infections. β-PVs (β-1) were the most prevalent and persistent. Age was associated with both the infection status (P=0.01) and the type of HPV infection (no infection, indeterminate/transient, persistent P=0.02). The molecular/phylogenetic analysis of the newly identified β-PV, officially designated as HPV209, showed that the virus has a typical genomic organization of cutaneous HPVs with five early (E6, E7, E1, E2 and E4) and two late genes (L2 and L1), which clusters to the species β-2. This provides useful data on cutaneous HPV infections in high UV-exposed regions.

The biology of beta human papillomaviruses

The beta genus comprises more than 50 beta human papillomavirus (HPV) types that are suspected to be involved, together with ultraviolet (UV) irradiation, in the development of non-melanoma skin cancer (NMSC), the most common form of human cancer. Two members of the genus beta, HPV5 and HPV8, were first identified in patients with a genetic disorder, epidermodysplasia verruciformis (EV), that confers high susceptibility to beta HPV infection and NMSC development. The fact that organ transplant recipients (OTRs) with an impaired immune system have an elevated risk of NMSC raised the hypothesis that beta HPV types may also be involved in skin carcinogenesis in non-EV patients. Epidemiological studies have shown that serological and viral DNA markers are weakly, but significantly, associated with history of NMSC in OTRs and the general population. Functional studies on mucosal high-risk (HR) HPV types have clearly demonstrated that the products of two early genes, E6 and E7, are the main viral oncoproteins, which are able to deregulate events closely linked to transformation, such as cell cycle progression and apoptosis. Studies on a small number of beta HPV types have shown that their E6 and E7 oncoproteins also have the ability to interfere with the regulation of key pathways/events associated with cellular transformation. However, the initial functional data indicate that the molecular mechanisms leading to cellular transformation are different from those of mucosal HR HPV types. Beta HPV types may act only at early stages of carcinogenesis, by potentiating the deleterious effects of other carcinogens, such as UV radiation.

Beta genus papillomaviruses and skin cancer

A role for the beta genus HPVs in keratinocyte carcinoma (KC) remains to be established. In this article we examine the potential role of the beta HPVs in cancer revealed by the epidemiology associating these viruses with KC and supported by oncogenic properties of the beta HPV proteins. Unlike the cancer associated alpha genus HPVs, in which transcriptionally active viral genomes are invariably found associated with the cancers, that is not the case for the beta genus HPVs and keratinocyte carcinomas. Thus a role for the beta HPVs in KC would necessarily be in the carcinogenesis initiation and not in the maintenance of the tumor.

Natural history of cutaneous human papillomavirus (HPV) infection in men: the HIM study

Accumulating evidence suggests that cutaneous human papillomavirus (HPV) infection is associated with non-melanoma skin cancer (NMSC). Little is known about the natural history of cutaneous HPV. A sub-cohort of 209 men with no NMSC history, initially enrolled in the HPV infection in men (HIM) study, were followed for a median of 12.6 months. Epidemiological data were collected through self-administered questionnaires. Cutaneous HPV DNA was measured in normal skin swabs (SS) and eyebrow hairs (EB) for 25 and 16 HPV types in genera β and γ, respectively. Any β HPV infection was more prevalent in SS (67.3%) compared to EB (56.5%, p = 0.04). Incidence in SS was higher than 20 per 1,000 person-months for HPV types 4, 5, 23, 38 and 76. Median duration of persistence of β and γ HPV infection was 8.6 and 6.1 months in EB, respectively, and 11.3 months and 6.3 months, in SS, respectively. Older age (>44 years vs. 18-30 years) was significantly associated with prevalent (SS OR = 3.0, 95% CI = 1.2–7.0) and persistent β HPV infection (EB OR = 6.1, 95% CI = 2.6–14.1). History of blistering sunburn was associated with prevalent (OR = 2.8, 95% CI = 1.3–5.8) and persistent (OR = 2.3, 95% CI = 1.2–4.6) β HPV infection in SS. Cutaneous HPV is highly prevalent in men, with age and blistering sunburn being significant risk factors for cutaneous β HPV infection.

Characterization of human papillomavirus type 154 and tissue tropism of gammapapillomaviruses

The novel human papillomavirus type 154 (HPV154) was characterized from a wart on the crena ani of a three-year-old boy. It was previously designated as the putative HPV type FADI3 by sequencing of a subgenomic FAP amplicon. We obtained the complete genome by combined methods including rolling circle amplification (RCA), genome walking through an adapted method for detection of integrated papillomavirus sequences by ligation-mediated PCR (DIPS-PCR), long-range PCR, and finally by cloning of four overlapping amplicons. Phylogenetically, the HPV154 genome clustered together with members of the proposed species Gammapapillomavirus 11, and demonstrated the highest identity in L1 to HPV136 (68.6%). The HPV154 was detected in 3% (2/62) of forehead skin swabs from healthy children. In addition, the different detection sites of 62 gammapapillomaviruses were summarized in order to analyze their tissue tropism. Several of these HPV types have been detected from multiple sources such as skin, oral, nasal, and genital sites, suggesting that the gammapapillomaviruses are generalists with a broader tissue tropism than previously appreciated. The study expands current knowledge concerning genetic diversity and tropism among HPV types in the rapidly growing gammapapillomavirus genus.

Mucosal and cutaneous human papillomaviruses detected in raw sewages

Epitheliotropic viruses can find their way into sewage. The aim of the present study was to investigate the occurrence, distribution, and genetic diversity of Human Papillomaviruses (HPVs) in urban wastewaters. Sewage samples were collected from treatment plants distributed throughout Italy. The DNA extracted from these samples was analyzed by PCR using five PV-specific sets of primers targeting the L1 (GP5/GP6, MY09/MY11, FAP59/64, SKF/SKR) and E1 regions (PM-A/PM-B), according to the protocols previously validated for the detection of mucosal and cutaneous HPV genotypes. PCR products underwent sequencing analysis and the sequences were aligned to reference genomes from the Papillomavirus Episteme database. Phylogenetic analysis was then performed to assess the genetic relationships among the different sequences and between the sequences of the samples and those of the prototype strains. A broad spectrum of sequences related to mucosal and cutaneous HPV types was detected in 81% of the sewage samples analyzed. Surprisingly, sequences related to the anogenital HPV6 and 11 were detected in 19% of the samples, and sequences related to the "high risk" oncogenic HPV16 were identified in two samples. Sequences related to HPV9, HPV20, HPV25, HPV76, HPV80, HPV104, HPV110, HPV111, HPV120 and HPV145 beta Papillomaviruses were detected in 76% of the samples. In addition, similarity searches and phylogenetic analysis of some sequences suggest that they could belong to putative new genotypes of the beta genus. In this study, for the first time, the presence of HPV viruses strongly related to human cancer is reported in sewage samples. Our data increases the knowledge of HPV genomic diversity and suggests that virological analysis of urban sewage can provide key information useful in supporting epidemiological studies.

Detection and typing of cutaneous human papillomavirus types--a comparison of three different methods

Cutaneous human papillomavirus (HPV) may play a role in the development of cutaneous squamous cell carcinoma. HPV copy numbers in cutaneous squamous cell carcinoma are very low and hence sensitive and reliable detection methods are important, particularly to examine the natural history of cutaneous HPV. In the present study, the presence of cutaneous HPV types was examined in 194 skin swabs and in a subgroup of 91 skin swabs, and compared using three different PCR based methods: (i) beta/gamma cutaneous HPV PCR reverse-line-blotting (BGC-PCR RLB), (ii) multiplex cutaneous papillomavirus genotyping (McPG) and (iii) FAP PCR. The HPV prevalence was 75% (68/91) with BGC-PCR RLB, 64% (124/194) with McPG and 72% (139/194) with FAP PCR. The agreement for the detection of HPV between the three methods in the subset of 91 samples was 73% (66/91; kappa=0.34) for BGC-PCR RLB and McPG, 75% (68/91; kappa=0.32) for BGC-PCR RLB and FAP PCR, and 69% (63/91; kappa=0.25) for McPG and FAP PCR. For McPG and FAP PCR, 194 specimens were tested in total, with an overall agreement of 66% (129/194; kappa=0.24) for the detection of HPV. The concordance between the three methods was moderate, which could be explained by different HPV types detectable with each method; the high number of multiple infections and the low viral copy number in human skin. Overall, many cutaneous HPV types were identified and multiple HPV types were found frequently in the human skin swabs.

Differential presence of Papillomavirus variants in cervical cancer: an analysis for HPV33, HPV45 and HPV58

BACKGROUND

Certain human papillomaviruses (HPVs) are the causative agents of cervical carcinomas in humans. The identification of the link between infection and cancer has resulted in the successful establishment of clinical strategies such as screening or vaccination programs, aiming to prevent this pathology. More than 150 different HPVs have been described and classified and the large majority of them are not related to cancer. The genus Alphapapillomavirus encompasses many PVs, some of which are identified in humans as oncogenic, according to the epidemiological connection between infection and cervical cancer. Variants of some of these "high-risk" HPVs may have an increased involvement in cervical cancer, although definitive data are still wanting. The aim of the present work was to analyze the presence of HPV33, HPV45 and HPV58 variants in cases of cervical cancer.

METHODS

Samples from cervical lesions in the context of different cervical cancer surveys were analyzed for presence of HPV DNA. Samples positive for HPV33, HPV45 or HPV58 DNA were selected and the E6/E7 genes were amplified and sequenced. The phylogenetic relationships of these sequences were inferred using an evolutionary placement algorithm and accordingly classified at the variant level.

RESULTS

All viral E6/E7 sequences were successfully placed in the classification schemes of the corresponding viruses. For HPV33 (n=23), 45 (n=61) or 58 (n=29), the distribution of variants found in cases of cervical cancer is not a random sample of the corresponding diversity. In all three HPVs, the respective A variants were more prevalent in the viral DNA-positive cases of cervical cancer analyzed. This is the first study trying to discern the phylogenetic connection between variants of the oncogenic HPV33, 45 and 58, and squamous cell carcinoma of the cervix.

Cutaneous squamous cell carcinoma and human papillomavirus: is there an association?

BACKGROUND

The role of human papillomavirus (HPV) in the induction and maintenance of cervical, anogenital, and some oropharyngeal carcinomas is well recognized, but its role in cutaneous squamous cell carcinoma (SCC) remains to be elucidated. HPV is thought to act as a possible cocarcinogen in the development of SCC.

OBJECTIVE

To review the literature assessing the correlation between and possible causation of HPV and cutaneous SCC in immunocompetent and immunocompromised populations.

METHODS

We reviewed HPV sampling and detection methods, epidemiologic studies examining HPV carriage in immunocompetent and immunosuppressed individuals, and evidence asserting an association between HPV and cutaneous SCC.

RESULTS

Although an abundant body of evidence points toward a link between HPV and cutaneous SCC, many studies indicate otherwise. Recent studies have focused on viral activity in addition to DNA presence.

CONCLUSION

The possibility exists that HPV may play a role in the induction but not maintenance of cutaneous SCC.

Human skin microbiota: high diversity of DNA viruses identified on the human skin by high throughput sequencing

The human skin is a complex ecosystem that hosts a heterogeneous flora. Until recently, the diversity of the cutaneous microbiota was mainly investigated for bacteria through culture based assays subsequently confirmed by molecular techniques. There are now many evidences that viruses represent a significant part of the cutaneous flora as demonstrated by the asymptomatic carriage of beta and gamma-human papillomaviruses on the healthy skin. Furthermore, it has been recently suggested that some representatives of the Polyomavirus genus might share a similar feature. In the present study, the cutaneous virome of the surface of the normal-appearing skin from five healthy individuals and one patient with Merkel cell carcinoma was investigated through a high throughput metagenomic sequencing approach in an attempt to provide a thorough description of the cutaneous flora, with a particular focus on its viral component. The results emphasize the high diversity of the viral cutaneous flora with multiple polyomaviruses, papillomaviruses and circoviruses being detected on normal-appearing skin. Moreover, this approach resulted in the identification of new Papillomavirus and Circovirus genomes and confirmed a very low level of genetic diversity within human polyomavirus species. Although viruses are generally considered as pathogen agents, our findings support the existence of a complex viral flora present at the surface of healthy-appearing human skin in various individuals. The dynamics and anatomical variations of this skin virome and its variations according to pathological conditions remain to be further studied. The potential involvement of these viruses, alone or in combination, in skin proliferative disorders and oncogenesis is another crucial issue to be elucidated.

Oncogenic HPV infection resembling pseudocondyloma of vulvae: a descriptive study of 31 cases

OBJECTIVE

Report a special type of human papillomavirus infection resembling pseudocondyloma of vulvae. The characteristics of the clinical manifestation and subtypes of the HPV infection were studied.

METHODS

Thirty-one women with unprotected sex and genital warts resembling pseudocondyloma of vulvae were involved in this study. The clinical and histological manifestations were characterized. The genotypes of human papillomavirus were determined by a reverse hybridization of polymerase chain reaction (PCR) RESULTS: Thirteen HPV genotypes were detected from 31 cases. Of 13 genotypes, 3 were non-oncogenic and 10 were oncogenic. At least, one of oncogenic genotypes was detected from each patient. Among 31 cases, 10 were found with one genotype of the HPV infection, 14 with 2 genotypes of HPV and 7 with at least 3 genotypes. The most common genotype was genotype 16 that was detected from 15 of 31 samples (48%).

CONCLUSION

There is a special type of oncogenic HPV infection clinically resembling pseudocondyloma of vulvae. Some of the patients who were infected with this type of HPV infection may have been misdiagnosed as pseudocondyloma of vulvae in the past time.

Roles of the immune system in skin cancer

Over the past several decades, there has been increasing interest in understanding the roles of the immune system in the development and progression of cancer. The importance of the immune system in human skin cancer has been long recognized based primarily upon the increased incidence of skin cancers in organ transplant recipients and mechanisms of ultraviolet (UV) radiation-mediated immunomodulation. In this review, we integrate multiple lines of evidence highlighting the roles of the immune system in skin cancer. First, we discuss the concepts of cancer immunosurveillance and immunoediting as they might relate to human skin cancers. We then describe the clinical and molecular mechanisms of skin cancer development and progression in the contexts of therapeutic immunosuppression in organ transplant recipients, viral oncogenesis, and UV radiation-induced immunomodulation with a primary focus on basal cell carcinoma and squamous cell carcinoma. The clinical evidence supporting expanding roles for immunotherapy is also described. Finally, we discuss recent research examining the functions of particular immune cell subsets in skin cancer and how they might contribute to both antitumour and protumour effects. A better understanding of the biological mechanisms of cancer immunosurveillance holds the promise of enabling better therapies.

The combined influence of oral contraceptives and human papillomavirus virus on cutaneous squamous cell carcinoma

The vast majority of cutaneous squamous cell carcinoma (CSCC) will occur in those with fair complexion, tendency to burn, and high ultraviolet radiation (UVR) exposure. Organ transplant recipients also are an important population at great risk for CSCC. An association has been reported between oral contraceptive (OC) use, human papillomavirus virus (HPV) and cervical cancer, and there could be a similar association for CSCC. The cutaneous HPV β-E6 protein, a close cousin of the transformative E6 protein underlying anogenital cancers, has been shown to inhibit apoptosis in response to UVR damage and stimulate morphologic transformation in rodent fibroblast cell lines. Furthermore, OC use has been shown to enhance HPV transcription and may contribute to CSCC risk through this pathway.

Current concepts on human papillomavirus infections in children

Current evidence is strong enough to conclude that human papillomavirus (HPV) can be transmitted both sexually and non-sexually. The debate on HPV infections in children still continues but it is more focused on HPV prevalence than on transmission modes. HPV DNA detection in amniotic fluid, foetal membranes, cord blood and placental trophoblastic cells all suggest HPV infection in utero, i.e. prenatal transmission. Based on recent meta-analysis, vertical transmission occurs in approximately 20% of cases. Most of the mucosal HPV infections in infants are incident, persistent infections in oral and genital mucosa being found in less than 10% and 2% respectively. The mother seems to be the main transmitter of HPV to her newborn, but subsequent HPV infections are acquired horizontally via saliva or other contacts. Bimodal peak prevalence is seen for skin warts, oral papillomas and recurrent respiratory papillomatosis (RRP) in younger and older age groups, suggesting similar epidemiology. Of the clinical HPV diseases, juvenile-onset-RRP and genital condylomata are problematic; the former because of its life-threatening potential and the latter because of possible sexual abuse. HPV6 and 11 are the most common genotypes in both the lesions. Early in life, infections by the high-risk HPV genotypes may also remain persistent for a considerable period, and should be of considerable importance for HPV vaccination strategies.

Identification of human papilloma virus type 6 in psoriasiform keratosis

Psoriasiform keratosis is a recently reported unique clinicopathological entity characterized by the appearance of a solitary lesion mimicking seborrheic keratosis, actinic keratosis, or squamous cell carcinoma and histopathologic features closely resembling psoriasis. We report a 74-year-old woman presenting with a solitary, scaly lesion on the dorsum of the left arm of several months duration and histopathologic findings of psoriasiform acanthosis of the epidermis with thinning of the suprapapillary plates and intraepidermal spongiform neutrophilic pustules, consistent with a diagnosis of psoriasiform keratosis. On additional work-up investigation, human papilloma virus type 6 was detected in the tissue examined by polymerase chain reaction technique, an association not described before.