Total body exposure to ultraviolet radiation does not influence plasma levels of immunoreactive beta-endorphin in man.

BACKGROUND/AIMS: A growing number of reports support evidence of proopiomelanocortin (POMC)-derived peptides in human skin cells, although not consistently. Also the effect of ultraviolet radiation (UVR) on cutaneous and plasma levels of these POMC peptides has not been established unequivocally. We hypothesized that production of beta-endorphin (betaE) may explain the sense of well-being many people experience when sun-bathing. The aim of the present study was to investigate whether exposure of the skin to UVR elevates plasma betaE. METHOD: Healthy volunteers (n=26) received a single, weighted dose of 15 J/cm2 of UVA. Several times during the hour following irradiation, plasma betaE- immunoreactivity (betaE-IR) was determined by radioimmunoassay. The effect of repeated exposure was assessed in 35 patients treated with UVB, UVA, or UVA-1. Plasma ACTH-IR was monitored in parallel. RESULTS: Overall, plasma levels of betaE-IR and ACTH-IR showed no significant changes during the experiment, indicating that these peptides are not influenced by single or repeated exposures to UVR of different wavelengths. CONCLUSION: On the basis of these results, the skin does not appear to contribute significantly to the levels of circulating betaE or ACTH. These data offer no support for the hypothesis that exposure to UVR leads to an increased concentration of circulating betaE, which could contribute to the feeling of well-being that often accompanies sun-bathing.

Presence of immunoreactive beta-endorphin in human skin.

The production and its induction by ultraviolet radiation (UVR) of proopiomelanocortin (POMC)-derived peptides by keratinocytes has been reported, albeit not consistently. Recently we demonstrated that only under specific culturing conditions human keratinocytes are capable of producing a beta-endorphin (betaE)-like peptide with the characteristics of beta-lipotropin (betaLPH). Here the presence and UV-induction of betaE-immunoreactivity (betaE-IR) in keratinocytes in human skin in vivo was investigated. betaE-IR was detectable by immunohistochemistry in keratinocytes of the follicular matrix and to some extent in cells of sweat ducts, but was absent from epidermal keratinocytes. Absence of betaE-IR was confirmed by radioimmunoassay of HPLC-fractionated extracts of normal epidermis. Repeated exposure to solar-simulated UVR had no effect. This investigation is the first to demonstrate the presence of betaE-immunoreactive material in the follicular matrix of corporal hairs and in duct cells of sweat glands. The possible meaning of these results is discussed.

The melanocortin-1-receptor gene is the major freckle gene.

Ephelides and solar lentigines are different types of pigmented skin lesions. Ephelides appear early in childhood and are associated with fair skin type and red hair. Solar lentigines appear with increasing age and are a sign of photodamage. Both lesions are strong risk indicators for melanoma and non-melanoma skin cancer. Melanocortin-1-receptor (MC1R) gene variants are also associated with fair skin, red hair and melanoma and non-melanoma skin cancer. The purpose of this study was to investigate the relationship between MC1R gene variants, ephelides and solar lentigines. In a large case-control study, patients with melanoma and non-melanoma skin cancer and subjects without a history of skin cancer were studied. In all participants, the presence of ephelides in childhood and solar lentigines by physical examination was assessed according to strict definitions. The entire coding sequence of the MC1R gene was analyzed by single-strand conformation polymorphism analysis followed by sequence analyses. Carriers of one or two MC1R gene variants had a 3- and 11-fold increased risk of developing ephelides, respectively (both P < 0.0001), whereas the risk of developing severe solar lentigines was increased 1.5- and 2-fold (P = 0.035 and P < 0.0001), respectively. These associations were independent of skin type and hair color, and were comparable in patients with and without a history of skin cancer. The population attributable risk for ephelides to MC1R gene variants was 60%, i.e. 60% of the ephelides in the population was caused by MC1R gene variants. A dosage effect was found between the degree of ephelides and the number of MC1R gene variants. As nearly all individuals with ephelides were carriers of at least one MC1R gene variant, our data suggest that MC1R gene variants are necessary to develop ephelides. The results of the study also suggest that MC1R gene variants play a role, although less important, in the development of solar lentigines.

Cutaneous squamous cell carcinoma and p53 codon 72 polymorphism: a need for screening?

The association between human papillomavirus (HPV)-associated cervical cancer and cutaneous squamous cell carcinoma and codon 72 polymorphism in the p53 gene is not unequivocal. Especially, it is not known whether carriers of the arginine form have an increased risk of cancer that necessitates screening. The alternative is that the polymorphism is a tumor marker instead of a risk factor. We set out a case-control study to determine the risk of squamous cell carcinoma of the skin in individuals with the p53 codon 72 arginine genotype in order to establish the possible need for screening. The distribution of the different p53 codon 72 genotypes was examined in 86 subjects with a history of cutaneous squamous cell carcinoma and in 168 controls. Additionally, 121 subjects who had had histologically proven basal cell carcinoma and 108 subjects who had had non-familial malignant melanoma were tested. p53 polymorphism was evaluated by polymerase chain reaction (PCR) using DNA samples from peripheral blood lymphocytes. In a subgroup of patients with squamous cell carcinoma and controls, the presence of epidermodyplasia verruciformis human papillomavirus (EV-HPV) DNA was determined in plucked eyebrow hair. Differences in the distributions of the genotypes among cases and controls were calculated, and univariate and multivariate analyses were performed to assess the risk to develop cutaneous squamous cell carcinoma in the presence of the p53 codon 72 arginine genotype. Frequency distributions of the three different genotypes (homozygous for the arginine allele, heterozygous for the two alleles, and homozygous for the proline allele) were similar among the squamous cell carcinoma group and the control group: 47.1%, 46.0% and 6.9% versus 47.8%, 45.8% and 6.4%, respectively. Statistical analysis showed no significant differences between these groups. In patients with squamous cell carcinoma and controls who harbored EV-HPV DNA in their plucked eyebrow hair, similar results were obtained. The distributions of the p53 codon 72 genotypes in the basal cell carcinoma and malignant melanoma group were also not significantly different from the control group. p53 codon 72 arginine homozygosity does not appear to represent a significant risk factor for cutaneous squamous cell carcinoma and screening seems not to be indicated. Mol. Carcinog. 30:56-61, 2001.

Melanocortin-1 receptor gene variants determine the risk of nonmelanoma skin cancer independently of fair skin and red hair.

Melanocortin-1 receptor (MC1R) gene variants are associated with fair skin and red hair and, independently of these, with cutaneous malignant melanoma. The association of MC1R gene variants with nonmelanoma skin cancer is largely unknown. A total of 838 subjects were included in the present study: 453 patients with nonmelanoma skin cancer and 385 subjects with no skin cancer. The coding sequence of the human MC1R gene was tested using single-stranded conformation polymorphism analysis followed by sequencing of unknown variants. Risk of skin cancer dependent on the various MC1R gene variants was estimated using the exposure odds ratio. We investigated whether subjects with MC1R variant alleles were at increased risk of developing nonmelanoma skin cancer and, if so, whether this increased risk was mediated by fair skin and red hair. A total of 27 MC1R gene variants were found. The number of carriers of one, two, or three MC1R gene variants was 379 (45.2%), 208 (24.8%), and 7 (0.9%), respectively. A strong association between MC1R gene variants and fair skin and red hair was established, especially the variants Arg151Cys and Arg160Trp (P < .0001). Carriers of two variant alleles were at increased risk for developing cutaneous squamous cell carcinoma (odds ratio 3.77; 95% confidence interval [CI] 2.11-6.78), nodular basal cell carcinoma (odds ratio 2.26; 95% CI 1.45-3.52), and superficial multifocal basal cell carcinoma (odds ratio 3.43; 95% CI 1.92-6.15), compared with carriers of two wild-type alleles. Carriers of one variant allele had half the risk. The highest relative risks of nonmelanoma skin cancer were found in carriers of the Asp84Glu, His260Pro, and Asp294His variant alleles, and the risk was only slightly lower for carriers of the Val60Leu, Val92Met, Arg142His, Arg151Cys, and Arg160Trp variant alleles. When subjects were stratified by skin type and hair color, analysis showed that these factors did not materially change the relative risks. These findings indicate that MC1R gene variants are important independent risk factors for nonmelanoma skin cancer.

Skin infections in renal transplant recipients.

BACKGROUND: Skin infection is a frequent complication in renal transplant recipients. The purpose of the study was to acquire long-term, period-specific incidence data on the most commonly occurring skin infections in renal transplant recipients. METHODS: A retrospective analysis was performed using medical records of 134 patients, covering a period between 10 and 29 yr. Cumulative incidences of the skin infections were calculated by counting the infections per patient for different time periods and were expressed as a percentage of the total group of patients. The incidence of the skin infections was determined for different post-transplant time periods. RESULTS: A total of 340 skin infections in 105 out of 134 patients were recorded. Some infections, such as candidal infection, herpes simplex infection, and impetigo were most prominent during the first post-transplant year and did not affect many new patients after the first year. Other infections, such as dermatomycoses, herpes zoster, and folliculitis were also affecting a substantial number of new patients after the first post-transplant year. CONCLUSIONS: This study confirms that skin infections among renal transplant recipients are very common and that the spectrum of skin infections differs according to the post-transplant time period.

Relation between smoking and skin cancer.

PURPOSE: Tobacco smoking is a risk factor for several cancers. The risk of cutaneous malignancies related to smoking, however, is relatively unknown. We investigated the possible association between smoking and skin cancer. PATIENTS AND METHODS: A hospital-based case-control study was performed that included 161 patients with squamous cell carcinoma, 301 with nodular basal cell carcinoma, 153 with superficial multifocal basal cell carcinoma, 125 with malignant melanoma, and 386 controls. Information on smoking history was collected in personal interviews. Relative risks were estimated using exposure odds ratios from cross-tabulation and logistic regression. RESULTS: An association between smoking and squamous cell carcinoma of the skin was found (relative risk, 2.3; 95% confidence interval, 1.5 to 3.6; P: = .0001), with a higher risk for current smokers (relative risk, 3.3; 95% confidence interval, 1.9 to 5.5) than for former smokers (relative risk, 1.9; 95% confidence interval, 1.2 to 3.0). After adjustment for age, sex, and sun exposure, the relative risk of squamous cell carcinoma was 2.0 (95% confidence interval, 1.2 to 3.2; P: = .008). There was a dose-response relationship with number of cigarettes and pipes smoked. No significant association was found between smoking and nodular basal cell carcinoma, superficial multifocal basal cell carcinoma, or malignant melanoma. CONCLUSION: Tobacco smoking is an independent risk factor for cutaneous squamous cell carcinoma.

Further evidence for an association of HLA-DR7 with basal cell carcinoma on the tropical island of Saba.

OBJECTIVE: To establish the association of HLA alleles (ie, HLA-DR1, HLA-DR4, and HLA-DR7) with individuals with skin cancer on the tropical island of Saba. This island was chosen because most of the white population has fair skin and excessive exposure to sunlight, which results in a high prevalence of skin cancer. DESIGN: HLA typing was performed in 124 white individuals with histologically proven basal cell and/or squamous cell carcinoma and in control subjects. Skin type, the presence of freckling, and the number of actinic keratoses were determined. SETTING: Population-based study. SUBJECTS: Inhabitants of Saba with and without skin cancer. MAIN OUTCOME MEASURE: Presence of HLA-DR1, HLA-DR4, and HLA-DR7 alleles. RESULTS: Associations of HLA alleles with basal cell and squamous cell carcinoma have been reported. The presence of the HLA-DR7 allele was positively associated with the development of basal cell carcinoma (odds ratio, 3.8; 95% confidence interval, 1.1-13.4). Adjustment for skin type, which is a potentially confounding factor for the association between HLA alleles and skin cancer, did not substantially alter this association. No other associations between HLA alleles and skin cancer were found, possibly because of the small size of the study population. CONCLUSION: This study presented further evidence for an association between HLA-DR7 and basal cell carcinoma. Arch Dermatol. 2000;136:1019-1022

Condition-dependent presence of beta-lipotropin-like peptide in human keratinocytes.

This study aimed to characterize the beta-endorphin-immunoreactive material (betaE-IR) detectable in normal human keratinocytes (NHK). The effects of different culturing conditions and UV-irradiation on production of betaE-IR by NHK were assessed by radioimmunoassay and HPLC. All culture systems contained low levels of betaE-IR that was increased in conditioned media after UV-irradiation under certain conditions. NHK grown in nutrient-poor medium contained highest levels of betaE-IR that exhibited beta-lipotropin-like properties after HPLC analysis. The other culturing conditions displayed no authentic betaE-related peptides. Our results indicate that under certain culturing conditions NHK can produce POMC peptides like beta-lipotropin, which can be induced by UV-radiation.

HPV-DNA is not detectable in outgrowing cells from explant cultures of skin lesions established at the air-liquid-interface.

Keratinocyte cultures established from HPV containing skin cancers were described earlier to lose their HPV DNA after passaging in vitro. A different approach was therefore used in this study. Explant cultures were generated by depositing small pieces of various benign and (pre)malignant skin specimens of renal transplant recipients and non-immunosuppressed patients on fibroblast-populated collagen lattices or on de-epidermized dermis. Subsequently, the cultures were maintained at the air-liquid interface. At various time points, samples were collected for both HPV analysis, using a nested PCR approach, and morphology. The outgrowing keratinocytes developed into multilayered epithelial structures showing terminal differentiation. No histological differences were observed between cultures established from HPV positive and negative lesions. Eighteen biopsy specimens were tested for their HPV content before and after culture. Before culture 11 out of these skin specimens contained DNA of the Epidermodysplasia Verruciformis-related HPV types (EV-HPV). Comparison of the HPV types detected in two different parts of the same skin specimen before culture was strongly suggestive for a non-homogeneous distribution of EV-HPV in the lesions. From the explant cultures derived from the 11 HPV-positive biopsies, 31 samples from the originally explanted pieces of tissue and 38 samples from the outgrowing multilayered epithelial sections were collected. HPV DNA was detected in 10 of the 31 and in 3 of the 38 samples (Chi-square test, P = 0.01), respectively. These results indicate that EV-HPV positive keratinocytes do not efficiently proliferate or lose their HPV DNA in this culture system or EV-HPV DNA is present in only a few basal cells, making it improbable that these cells are located at the outgrowing margins.

Skin equivalent: an attractive model to evaluate early melanoma metastasis.

The growth patterns and morphological phenotype of four human melanoma cell lines with different metastatic potentials were investigated in submerged and in air-exposed (skin equivalent) keratinocyte-melanoma cell co-cultures. In contrast to the submerged co-cultures, all four cell lines formed sharply demarcated tumour cell nests within the epidermal compartment of the skin equivalent model, with the morphology highly mimicking the in vivo situation. Differences among the melanoma cell lines tested were observed with respect to the number of clusters formed and the ability to exhibit invasive growth. Only the two metastatic cell lines were able to invade the dermal compartment. Screening of cellular adhesion molecules revealed that the expression patterns in different cell lines were heterogeneous and remained unchanged during the whole culture period, irrespective of whether the melanoma cells were located in the epidermal or dermal compartment. A correlation was found between expression of a lower number of different cellular adhesion molecules and the ability to acquire invasive growth capability. Our results indicate that melanoma cells exhibit a heterogeneous growth behaviour when co-cultured with human keratinocytes, and the air-exposed skin equivalent model was shown to be suitable for studying differences in growth patterns and potential invasive behaviour.

Patients' illness perceptions and coping as predictors of functional status in psoriasis: a 1-year follow-up.

In a longitudinal study (two measurements with a 1-year interval), 69 patients with psoriasis completed the Illness Perception Questionnaire, the Medical Outcomes Study SF-20 Health Survey, and the Hospital Anxiety and Depression Scale. Data on coping (Utrecht Coping List) and severity of illness (body surface scores) were also collected. The results of regression analyses indicated that a strong illness identity was associated with more visits to the outpatient clinic, and worse outcome on physical health, social functioning, mental health, health perceptions and depression. Strong beliefs that the disease is controllable/curable and that the disease has disabling consequences were also related to more clinic visits and more negative perceived health, respectively. Patients who initially engaged in coping characterized by more expression of emotions, seeking more social support, seeking more distraction, and less passive coping were prescribed a lower number of different therapies, were less anxious, less depressed, and had a better physical health 1 year later. These results have implications for the management of patients with psoriasis, which reinforces current views on integrating psychosocial aspects into clinical care.

The prevalence of human papillomavirus DNA in benign keratotic skin lesions of renal transplant recipients with and without a history of skin cancer is equally high: a clinical study to assess risk factors for keratotic skin lesions and skin cancer.

UNLABELLED: DNA of the epidermodysplasia-verruciformis associated subgroup of HPV (EV-HPV) is frequently detected in biopsies of premalignant lesions and nonmelanoma skin cancers of renal transplant recipients. The prevalence of EV-HPVs, however, has never been systematically studied in benign keratotic skin lesions of patients with or without a history of skin cancer. This study included 42 renal transplant recipients with and 36 without a history of skin cancer. A total of 176 skin biopsies were tested for the presence of EV-HPV DNA, using a nested polymerase chain reaction (PCR). METHOD: EV-HPV typing was done by comparison of the sequence of the amplified PCR products with the sequence of all known EV-HPVs. The natural history of the development of keratotic skin lesions was studied. The number of keratotic skin lesions rapidly increased after transplantation. This increase was most pronounced in patients who developed skin cancer. The prevalence of EV-HPV DNA in benign keratotic skin lesions was equally high in patients with and without a history of skin cancer, i.e., 55 and 53% in the two groups, respectively. A large variety of EV-HPV types was found, but of these none were predominantly present in either patient groups. A higher prevalence of EV-HPV DNA was found in benign skin lesions from sun-exposed sites, but only in patients with a history of skin cancer. The association between the number of keratotic skin lesions and the development of skin cancer strongly supports the hypothesis that EV-HPVs play a role in cutaneous oncogenesis. The equally high prevalence of EV-HPV infection in patients with and without a history of skin cancer, however, may indicate that besides EV-HPV infection, other factors, such as sun exposure may also be important.

The presence of antibodies against virus-like particles of epidermodysplasia verruciformis-associated humanpapillomavirus type 8 in patients with actinic keratoses.

Epidermodysplasia verruciformis-associated human papillomaviruses (EV-HPVs) are possibly involved in the development of actinic keratoses and may play a part in the pathogenesis of squamous cell carcinoma (SCC) of the skin, as the DNA of these viruses is frequently detected in biopsies of such lesions. Properly designed epidemiological studies, using serological tests to investigate the role of infection with EV-HPVs in cutaneous oncogenesis, are still rare. An IgG-specific enzyme-linked immunosorbent assay using virus-like particles composed of the major capsid protein L1 of the EV-specific HPV 8 (HPV 8 VLPs) was developed and used to test the seroprevalence of HPV 8 in 114 inhabitants of a tropical island, of whom 13 had developed SCC, and 19 had developed basal cell carcinoma. Gender, age, eye and hair colour, sun exposure and number of actinic keratoses were recorded for all individuals. The presence of antibodies against HPV 8 VLPs was associated with the development of large numbers of actinic keratoses. After adjusting for gender, age, eye and hair colour, and sun exposure, the odds ratio to develop 37 (the median in this dataset) or more actinic keratoses in the presence of antibodies against HPV 8 VLPs was 2.3 (95% confidence interval: 1.0; 5.3). Similarly, after adjustment for the same factors, the presence of these antibodies was associated with SCC with an odds ratio of 3.1 (0.74; 13.3), but the small number of individuals with SCC does not permit any definite conclusions. The presence of these antibodies did not appear to be associated with basal cell carcinoma as, after adjustment for the same factors, the odds ratio was 0.73 (0.23; 2.4). This study provides serological evidence that infection with EV-HPVs may play a part in the pathogenesis of actinic keratoses. The role of EV-HPVs in the development of SCC, however, remains to be elucidated.

Ephelides are more related to pigmentary constitutional host factors than solar lentigines.

Ephelides and solar lentigines are benign pigmented spots, which are currently associated with an increased risk of skin cancer. These two pigmented spots are known to be discriminated by their clinical, histological, and electron microscopic characteristics, even though occasional misclassification can occur because of their similarity. It has also been questioned whether these spots are not one and the same. In this study, we have attempted to differentiate between these two pigmented spots with the use of a standardized protocol for clinical examinations on 272 healthy volunteers, paying particular consideration to their pigmentary and constitutional host factors. We found that solar lentigines 1) are more prevalent than ephelides, 2) increase in prevalence and number with higher age, and 3) are most prevalent on the trunk and occur more frequently in males than in females. A trend is also observed whereby ephelides 1) loose their prevalence with age, 2) become equally distributed on the face, arms, and trunk, and 3) occur more frequently in females. An intimate association of ephelides, but not solar lentigines, has been found with hair color and skin type. All of these findings are in agreement with most of those reported in the literature, supporting the view that ephelides and solar lentigines are different types of pigmented lesions.

[Ultraviolet A-I phototherapy for skin diseases]. / Toepassingen van ultraviolet-A-I-licht binnen de fotodermatologie.

Favourable effects of sunlight on various skin diseases include inhibition of rapid proliferation of cells (psoriasis), modulation of cells in an inflammatory infiltrate (atopic eczema) and stimulation of proteolytic enzymes (scleroderma). The ultraviolet (UV) fraction of the solar spectrum is the most biologically active because it is almost completely absorbed by the skin. UVB and the combination of psoralens with UVA (PUVA) have become important therapeutic modalities, especially for psoriasis and eczema. Lamps producing long wave UV radiation are available: UVA-I light. Owing to its longer wavelength it penetrates more deeply into the skin and gives less risk of development of skin cancer than other forms of UV radiation. Good results are reported of application of UVA-I in patients suffering from atopic dermatitis, scleroderma, urticaria pigmentosa, and systemic lupus erythematosus.

L.I.ON. Study: efficacy and tolerability of continuous terbinafine (Lamisil) compared to intermittent itraconazole in the treatment of toenail onychomycosis. Lamisil vs. Itraconazole in Onychomycosis.

We undertook a prospective, randomised, double-blind, double-dummy, multicentre, parallel-group study to compare the efficacy and tolerability of continuous terbinafine (Lamisil) with intermittent itraconazole (Sporanox) in the treatment of toenail onychomycosis. A total of 496 patients (age range 18-75 years) with a clinical diagnosis of dermatophyte toenail onychomycosis, confirmed by positive mycological culture and microscopy (KOH), were recruited from 35 centres in six European countries. They were randomly divided into four parallel groups to receive either terbinafine 250 mg/day for 12 or 16 weeks (groups T12 and T16), or itraconazole 400 mg/day for 1 week in every 4 weeks for 12 or 16 weeks (groups I3 and I4). The primary efficacy measurement at week 72 was mycological cure, defined as negative microscopy and negative culture of samples from the target toenail. At week 72, the mycological cure rates were 75.5% (81/107) in the T12 group and 80.8% (80/99) in the T16 group, compared with 38.3% (41/107) in the I3 group and 49.1% (53/108) in the I4 group. All comparisons (T12 vs. I3, T12 vs. I4, T16 vs. I3, T16 vs. I4) showed significantly higher cure rates in the terbinafine groups (all P<0.0001). In addition, all secondary clinical outcome measures were significantly in favour of terbinafine at week 72. Both treatments were well tolerated, with no significant differences in the number or type of adverse events reported. We conclude that continuous terbinafine is significantly more effective than intermittent itraconazole in the treatment of toenail dermatophyte onychomycosis.

Variations in melanin formation by cultured melanocytes from different skin types.

In many laboratories, culturing skin melanocytes has become a routine research activity. However, recent investigations have revealed that the quality and quantity of the pigment formed in the cultured cells may differ significantly from those of the original skin pigment cells. To shed more light on this issue, we examined the influence of different culture media on pigment production. We showed that there were notable passage-to-passage variations in the synthesis of melanin. This was particularly true for phaeomelanin. It is therefore advisable to analyse the melanin in the cells before the start of experiments. In spite of the variations, basic differences in the pigmentation pattern between melanocytes isolated from light-skinned and dark-skinned individuals remained preserved in the corresponding cultures as observed by electron microscopy. Also, the total melanin content was higher in a skin type VI melanocyte culture than in skin type I and II melanocyte cultures. In contrast to total melanin, the phaeomelanin concentration of skin type VI cells was similar to that of the skin type I melanocytes. With higher L-tyrosine concentrations in the medium, as well as increased eumelanin synthesis, phaeomelanogenesis was also stimulated in all cultures tested. This stimulation was particularly prominent in skin type I melanocytes. Our preliminary experiments also showed that a melanocyte culture from atypical naevus cells exhibited a similar preference for phaeomelanogenesis when pigmentation was stimulated.

Differences in age, site distribution, and sex between nodular and superficial basal cell carcinoma indicate different types of tumors.

Basal cell carcinomas (BCC) are among the most common cancers in white subjects. Etiologic factors include ultraviolet and ionizing radiation, chemical carcinogens, and possibly infection with human papillomaviruses. Because of clinical and histologic differences, differential pathogenetic mechanisms have been suggested for different BCC subtypes. We studied the patient and tumor characteristics of all BCC diagnosed and/or treated at the departments of Dermatology and Plastic Surgery of our hospital between 1985 and 1996, and a review of the literature was carried out. Some important differences between patients with nodular BCC and patients with superficial BCC were observed. The frequency of superficial BCC was higher in females and was seen in younger patients as compared with nodular BCC. The latter occurred mainly in the head/neck region: in males they were seen more frequently on the ears, and in females they were predominantly seen on the eyelids, the lips, and in the neck. Superficial BCC occurred mainly on the trunk, and occurred significantly more often on the trunk in males than in females, where the legs were the most common site. These findings strongly suggest that the superficial subtype is a separate group within the clinical entity of BCC. Furthermore, our findings seem to support the etiologic role of sun exposure in these tumors; however, this role may be different for each subtype. Chronic sun exposure may be an etiologic factor in nodular BCC as compared with intermittent sun exposure in superficial BCC. Other factors, such as differences in site specific host factors and referral bias, may also play a role in the differences found between the subtypes.