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Preoperative assessment of Breslow thickness by means of sonography and clinical and dermoscopic criteria in white light dermoscopy has been reported, but up until now, the use of multispectral dermoscopy has not been investigated. Aim of this research is to determine whether multispectral dermoscopy and more specifically pigment maps can be used as a predictive marker for Breslow thickness in melanoma. Pigment maps are generated in real time from multispectral dermoscopic images and help to visualize the presence of pigment in a lesion. Multispectral images of 110 melanomas were collected, using a digital handheld multispectral dermatoscope, and assessed independently by five observers for the presence or absence of deep pigment compared with the surrounding skin. According to histopathological examination, the mean Breslow thickness of all 110 melanomas was 1.04 mm (ranging from 0.1 to 14 mm). The group of melanomas where deep pigment was visualized on the multispectral image (n = 78) had a significantly higher Breslow thickness (1.19 mm) than the group where no deep pigment was observed (n = 32, mean Breslow 0.68 mm) (P = 0.025). This study is unique in preoperative assessment of tumour thickness by means of multispectral dermoscopy. Our data indicate that the presence of deep pigment as visualized in digital dermoscopic skin parameter maps identifies a group of thicker melanomas. Further prospective research is needed to validate these pigment maps, generated by multispectral dermoscopy as a measure to predict invasiveness in melanoma.

UNSTRUCTURED Despite skin toxicity during anti-EGFR therapy occurs frequently and significantly impacts patients’ quality of life, it is often not recognized nor optimally managed. This may lead to unnecessary dose reductions or treatment discontinuations of the cancer treatment. Access to rapid dermatology advice may be limited in hospitals. In this multicenter pilot study, we conclude that teledermatology may add value for both patients and oncologists in the management of treatment-induced skin toxicity.

Background Early detection of skin cancer is still a major challenge in dermatology practice today. While surveillance programs are offered to high-risk patients, systematic total-body examination (TBE) in the general population is not cost-effective. In the past, we demonstrated that a lesion-directed screening (LDS) in the general population delivered similar detection rates to TBE and was less time-consuming. Objectives To study whether a lesion-directed early-access consultation can optimize skin cancer detection in dermatology practice. Methods In this observational study, we offered an early-access consultation in patients contacting the dermatology department concerning 1 or 2 lesions of concern meeting predefined criteria. Results 342 persons were seen at the dermatology department after triage by phone. Skin cancer detection rate was 13.2% (4.1% for melanoma). If advised/referred by a doctor skin cancer detection rate was 23.6% (9% for melanoma). With a history of skin cancer, detection rate was 24.3% (4.3% for melanoma). In patients with no referral and a negative history of skin cancer, detection rate was 7.7% (1.7% for melanoma), which is at least triple the rates reported by population-based screening programs. In patients in whom the index lesion was benign, worry of having skin cancer had decreased significantly by the end of the consultation. Additional total-body examination in these patients had low additional detection rate (0.5%) and a high number of unnecessary excisions (number needed to excise 13). Conclusions An early-access dermatology consultation for LDS after triage by phone resulted in high overall skin cancer and melanoma detection rates. Our data indicate that performing TBE is especially useful if the index lesion is suspicious. In addition to surveillance programs in high-risk patients, LDS may be a way to optimize skin cancer detection in the general population and use available time more efficiently in daily dermatology practice.

Background and objectives Dermoscopy has proven its value in the diagnosis of skin cancer and, therefore, is well established in daily dermatology practice. Up until now, analogue white light dermoscopy is the standard. Multispectral dermoscopy is based on illumination of the skin with narrowband light sources with different wavelengths. Each of these wavelengths is differently absorbed by skin chromophores, such as pigment or (de)oxygenated blood. Multispectral dermoscopy could be a way to enhance the visualization of vasculature and pigment. We illustrate possible additional information by such "skin parameter maps" in some cases of basal cell carcinoma and Bowen's disease. Methods Using a new digital multispectral dermatoscope, skin images at multiple wavelengths are collected from different types of skin lesions. These particular images together with the knowledge on skin absorption properties, result in so called "skin parameter maps". Results A "pigment contrast map," which shows the relative concentration of primarily pigment, and a "blood contrast map" which shows the relative concentration of primarily blood were created. Especially, the latter is of importance in diagnosing keratinocyte skin cancer hence vascular structures are a characteristic feature, as further illustrated in the study. Conclusions Skin parameter maps based on multispectral images can give better insight in the inner structures of lesions, especially in lesions with characteristic blood vessels such as Bowen's disease and basal cell carcinoma. Skin parameter maps can be used complementary to regular dermoscopy and could potentially facilitate diagnosing skin lesions.

This case report describes a man in his 60s who was referred to the department of dermatology for further evaluation of a lesion on the nose.

Background Laser-assisted photodynamic therapy is being explored as a method to enhance efficacy of photodynamic therapy (PDT). Objective To compare a continuous (CL) and a fractional (FL) ablative CO2 laser-assisted methyl aminolevulinate (MAL) PDT in the management of superficial basal cell carcinoma (sBCC) and Bowen's disease (BD). Methods Thirty treatment areas in fifteen patients with inoperable, histologically verified sBCC or BD received CL or FL after intrapatient randomization. Laser treatment was followed by MAL application and illumination occurred 3 h later. This treatment was repeated after 2 weeks. An equivalence analysis was performed on the primary endpoint efficacy, while secondary endpoints pain, side-effects and aesthetics were evaluated using paired samples tests. Patients were also asked for their preferred treatment. Results An excellent efficacy of 92.9% (sBCC, 100%; BD, 80%) was found in both CL + PDT and FL + PDT after 12 months. Equivalence could not be established. Little pain was perceived in most patients during PDT illumination. PDT treatment in FL + PDT was less painful, significantly during the second treatment (P = 0.026). Side-effects were mild to moderate with erythema being the most frequent immediate side-effect, followed by oedema, crusting and burning sensation. Pigmentary changes occurred in 21% (CL + PDT) to 29% (FL + PDT), and aesthetics were good to excellent in all patients. CL + PDT and FL + PDT did not significantly differ in side-effects (P = 0.219-1.000) or aesthetics (P = 0.157-1.000). Conclusions Results in this pilot study support the promising role of laser-assisted PDT. Both treatment arms demonstrated the same efficacy as well as comparable side-effects and aesthetics. PDT illumination was significantly less painful in the FL + PDT group, suggesting a preference for FL + PDT. The authors recommend further investigation with a larger sample size, a subgroup analysis between sBCC and BD and comparison of different treatment protocols before one technique could be preferred to another.

Background: Teledermatology, the application of telemedicine in the field of dermatology, can be a valuable tool to improve the efficiency of care in general practice.Objectives: In this pilot stud...

About one in five of the tattooed individuals regrets their tattoo(s) and considers removal. Some make an unwise decision and try chemical and thermal methods which mostly result in permanent disfiguring scars. Nowadays treatment with specific lasers offers the best solution. Q-switched lasers have become the first choice. However, laser tattoo removal is painful, tedious, expensive, and not always successful. To avoid dissatisfaction, good knowledge of the devices and patient selection is needed. Professional advice, correct information of the potential side effects, and good aftercare are required.

Background: The pathogenesis of vitiligo remains a topic of extensive debate. This is partly due to the moderate efficacy of current treatments. The role of the oxidative stress pathway in vitiligo is a popular although controversial research topic. Objective: To clarify the role of the oxidative stress pathway in vitiligo compared to other inflammatory skin disorders and to assess the therapeutic role of antioxidants. Methods: We conducted a systematic search of the existing literature on the aberrancies of the oxidative stress pathway in vitiligo. Subsequently, the efficacy of both topical and oral antioxidants in clinical trials was investigated. Results: A deregulated oxidative pathway is clearly evident with elevated superoxide dismutase, decreased catalase and increased lipid peroxidation. However, similar results have been obtained in other inflammatory skin diseases such as psoriasis, atopic dermatitis, lichen planus and urticaria. This questions the unique role of oxidative stress in the development of vitiligo. Some isolated successes have been reported with oral ginkgo biloba, polypodium leucotomos and vitamin C and E preparations, while other clinical trials have failed to show reproducible results. The use of topical antioxidants delivers in general no beneficial results. Conclusion: The oxidative pathway is affected in vitiligo, but its unique initiating or contributory role in the pathogenesis is less evident. Interesting data support the added value of oral antioxidants in vitiligo although confirmatory studies are missing.

Head lice infestations are very common in children aged between 3 and 12 yr old. The eggs of the head louse are difficult to remove and remain firmly attached to the hair even after any head louse treatment. Solid in vitro and in vivo evidence to support the use of any of the proposed products to facilitate nit removal is scarce. The objective of the current study was to determine the efficacy of several products to remove eggshells from human hair using an objective measurement procedure. Water and ordinary hair conditioner significantly facilitated the removal of nits in vitro. We found no difference between ordinary conditioner and products specifically marketed for the purpose of nit removal. Other products such as formic acid solution and almond oil did not have a beneficial effect.

Postoperative scarring is a common cause of patient dissatisfaction. Several strategies have been developed to improve its clinical aspects.To assess efficacy and safety of the 10,600 nm ablative fractional carbon dioxide (CO2) laser in the treatment of recent surgical scars in the head and neck region.A prospective, randomized, single-blind intrapatient controlled study was conducted on 9 postoperative scars in the head and neck region. On half of the scar, 3 treatment sessions were performed. Physician/Patient Global Assessment (PhGA/PGA) and Patient and Observer Scar Assessment Scales (POSAS) were used to evaluate treatment efficacy. Safety was evaluated by registration of pain and adverse events.No statistically significant differences were noted in terms of PhGA or POSAS (observer). Patient Global Assessment (p = 0.058) and POSAS (patient) (p = 0.091) showed a trend toward better improvement of the treated half. Itch score (p = 0.046) and global end evaluation (patient) (p = 0.026) demonstrated a statistically significant difference in favor of the treated part. Adverse events were minor, and no long-term side effects were noted.The use of CO2 fractional laser is safe and is associated with high patient satisfaction. However, objective measurements could not confirm its efficacy in the treatment of recent surgical scars.

Background Mohs micrographic surgery is a tissue sparing surgical technique for removal of skin cancer. To optimize the cosmetic result of scars and skin grafts after surgery non invasive procedures as non-ablative fractional laser (NAFL) resurfacing are attractive. Objective To evaluate efficacy and safety of 1540 nm NAFL in the treatment of scars and skin grafts after Mohs micrographic surgery. Methods An intra-individual randomized controlled trial (RCT) with split lesion design and single blinded outcome evaluations. Patients receive four treatments at monthly interval with NAFL [StarLux-300 with Lux 1540 nm fractional handpiece (Palomar technologies)]. Primary endpoint to evaluate efficacy is a blinded on site visual and palpable Physician Global Assessment (PhGA). Adverse event and pain registration are used to evaluate safety. Patient’s global assessment (PGA) and skin reflectance measurements are secondary endpoints. Results The PhGA score comparing the treated to the untreated control side of 24 patients is significant different 1 (P = 0.009) and 3 (P = 0.001) months after treatment (Wilcoxon signed rank test). Patients experienced mild to moderate pain. Four days after the treatments patients reported erythema (67%), oedema (31%), crusts (22%), burning sensation (14%), purpura (9%) and vesicles (4%). No long term adverse events are reported. PGA is significant different 1 (P

Segmental vitiligo and generalized vitiligo are in general considered to be separate entities. The aetiopathogenesis of segmental vitiligo remains unclear, although several hypotheses have been put forward including mainly neuronal mechanisms. The typical association with other autoimmune diseases, as seen in generalized vitiligo, seems to be significantly less in segmental vitiligo, although recent insights point towards a possible immune-mediated overlap between the two subtypes. In this article, we describe a case with simultaneous presence of segmental vitiligo, alopecia areata, psoriasis and a halo naevus. To our knowledge, this is the first case with this exceptional combination. This concomitant presence could support the involvement of a shared autoimmune-mediated process, and may provide new insights into the pathogenesis of segmental vitiligo and direct future research. In the light of this remarkable case, different possible aetiopathogenetic mechanisms leading to the clinical presentation of segmental vitiligo are discussed and a new three-step theory is proposed.

Background: Limited data are available about the use of 308-nm monochromatic excimer light (MEL) and localized 311-nm narrow-band ultraviolet B (NB-UVB) in the treatment of vitiligo. The aim of this study was to evaluate the efficacy of 308-nm MEL versus localized 311-nm NB-UVB in vitiligo patients. Methods: Eleven patients participated in this prospective intrapatient placebo-controlled randomized trial. In each patient, 3 lesions were selected and treated with NB-UVB, MEL and placebo during 24 sessions, respectively. Repigmentation was evaluated clinically and by objective surface measurement. Results: Twenty percent of the lesions treated with NB-UVB achieved repigmentation scores above 50%. None of the lesions treated with MEL achieved a repigmentation higher than 50% after 24 sessions. Conclusion: Localized 311-nm NB-UVB is effective in the treatment of vitiligo. It should be considered for localized vitiligo as it is easily accessible. In this study the efficacy of localized 311-nm NB-UVB was superior to 308-nm MEL.

Hemangiomas can present a difficult problem in management. Much controversy exists over whether it is better to watch and wait for natural involution or to be more aggressive and attempt to prevent some of the potential negative sequelae. Different modalities have been employed in the treatment of hemangiomas, including systemic therapy – antiangiogenic drugs, i.e. systemic corticosteroids and α-interferon – and local therapy – surgical procedures, arterial embolization and cryotherapy. Overall, a very conservative approach to therapy has been recommended because of treatment risks, treatment inadequacy and lack of evidence showing superiority over natural involution. Recently laser treatment has been used in the therapeutic approach of hemangiomas. This review discusses the pros and contras of early laser treatment of hemangiomas. For superficial hemangiomas, the flashlamp pumped pulsed dye laser in particular has proven itself in numerous studies. In the treatment of hemangiomas with subcutaneous components, the Nd:YAG laser is the treatment of choice.

When a biopsy is taken of a suspicious pigmented skin lesion, histological examination is expected to establish the definitive diagnosis. This study evaluated the inter-observer variation of 20 pathologists in the histological diagnosis of a randomly selected set of suspicious pigmented skin lesions (PSLs), by comparing their diagnoses to a reference diagnosis. Overall sensitivity for melanoma was 87%, ranging from 55% to 100% between the observers. Sensitivity was significantly lower for thin (Breslow thickness

Head lice infestations are very common in children aged between 3 and 12 yr old. The eggs of the head louse are difficult to remove and remain firmly attached to the hair even after any head louse treatment. Solid in vitro and in vivo evidence to support the use of any of the proposed products to facilitate nit removal is scarce. The objective of the current study was to determine the efficacy of several products to remove eggshells from human hair using an objective measurement procedure. Water and ordinary hair conditioner significantly facilitated the removal of nits in vitro. We found no difference between ordinary conditioner and products specifically marketed for the purpose of nit removal. Other products such as formic acid solution and almond oil did not have a beneficial effect.

Background: Early recognition of melanoma is the key in preventing metastatic disease. Objective: The aim of this study was to evaluate diagnostic ability of general practitioners (GPs) and dermatologists concerning pigmented skin lesions in general and melanoma in particular. We also investigated whether the diagnostic ability of GPs changed after a lecture on melanoma. Methods: A test set of 13 pigmented skin lesions on 35-mm color slides was presented to 160 GPs and 60 dermatologists during educational courses. Results: GPs correctly evaluated biologic behavior of the pigmented skin lesions in 72% of the evaluations. In 71% of these evaluations they correctly identified the lesions. The proportion of lesions correctly identified was positively correlated with the frequency of pigmented skin lesions in everyday practice. Dermatologists made a correct identification of the lesions in 88% of all evaluations, and they correctly evaluated biologic behavior in 94% of these. Recognition of melanoma was proportional to melanoma exposure in everyday practice. Thick melanomas were better recognized than thin melanomas in both physician groups. After a lecture on melanoma, sensitivity of GPs to recognize malignant disease increased from 72% to 84%, without a significant decrease in specificity. The proportion of lesions correctly identified also rose significantly (66% vs 52%). (J Am Acad Dermatol 2001;44:979-86.)

Delay in melanoma diagnosis was investigated in a population-based sample of 130 patients. The median time elapsing from the first notice of the lesion to excision was 110.5 days. There was no linear correlation between total delay time and Breslow-thickness of the diagnosed melanomas (P=0.19). Patient delay, defined as the time from first notice of a (change in a) lesion to the first observation by a physician, exceeded 2 months in half of all patients. Only 41% of the patients consulted a doctor because they were worried about the lesion. Colour change and itch were associated with a longer patient delay. There was no correlation with age, gender, socio-economic factors, localisation of the lesion and the person who first noticed the lesion. In one quarter of all patients, the time from first observation by a physician to excision of the lesion exceeded 2.5 months. This physician delay seemed to be attributed to misdiagnosis and to a delay occurring during referral.

Our knowledge concerning the effects of testosterone (T) therapy on the skin of trans men (female-to-male transsexuals) is scarce.The aim of this study was to evaluate the short- and long-term clinical effects of T treatment on the skin of trans men.We conducted a prospective intervention study in 20 hormone naive trans men and a cross-sectional study in 50 trans men with an average of 10 years on T therapy.Acne lesions were assessed using the Gradual Acne Grading Scale, hair patterns using the Ferriman and Gallwey classification (FG), and androgenetic alopecia using the Norwood Hamilton Scale.T treatment increased facial and body hair growth. The FG score increased progressively from a median value of 0.5 at baseline to a value of 12 after 12 months of T administration. After long-term T treatment, all but one trans man achieved an FG score indicative of hirsutism in women, with a median value of 24. Only one trans man acquired mild frontotemporal hair loss during the first year of T treatment, whereas 32.7% of trans men had mild frontotemporal hair loss and 31% had moderate to severe androgenetic alopecia after long-term T therapy. The presence and severity of acne increased during the first year of T therapy, and peaked at 6 months. After long-term T treatment, most participants had no or mild acne lesions (93.9%). Dermatological outcome was not demonstrably related to individual serum T or dihydrotestosterone levels.T treatment increased facial and body hair in a time-dependent manner. The prevalence and severity of acne in the majority of trans men peaked 6 months after beginning T therapy. Severe skin problems were absent after short- and long-term T treatment.

This article focuses on the actual management of cutaneous melanoma, dealing both with established, internationally well-accepted standard procedures and interventions which are still being investigated. It wants to offer a global picture to the dermatologist of what is currently available in the therapeutic arsenal against melanoma.

The overall underestimation of incident cancer cases in the Belgian National Cancer Registry is estimated at about 20-25%, with a probable larger under-registration among males. Melanoma incidence is suspected to be underestimated even further because of the hospital-based reporting system of the National Cancer Registry. To investigate the suspected underestimation of melanoma in Belgium, the official data were compared with international data on melanoma incidence and the results of a melanoma registration programme launched in the province of East Flanders. The Eindhoven Cancer Registry, which covers a registration area near the Belgian border, was used as a reference to calculate the expected number of melanomas in East Flanders for 1995. The results indicate an ongoing under-registration of melanoma cases by the National Cancer Registry. Based on the Eindhoven Cancer Registry data, the under-registration in East Flanders is estimated at 43% for males and 36% for females. The East Flanders registration programme apparently obtains a better registration in females. This is mainly due to a higher registration in the younger age groups. In these groups a higher proportion of in situ melanomas and a thinner median Breslow thickness of the invasive melanomas is observed.

Background : Nonablative fractional laser (NAFL) therapy is a noninvasive procedure that has been suggested as a treatment option for hypertrophic scars. Objectives To evaluate the efficacy and safety of 1540-nm NAFL therapy in the treatment of hypertrophic scars. Materials and Methods : An intraindividual randomized controlled trial (RCT) with split lesion design and single-blinded outcome evaluations. Patients received four NAFL treatments at monthly intervals. Primary endpoint was a blinded on-site visual and palpable Physician Global Assessment (PhGA). Adverse event registration and pain evaluation were used to evaluate safety. Patient global assessment (PGA) was a secondary endpoint to additionally evaluate efficacy. Results : The PhGA did not find a statistically significant difference between the treated and untreated control side of 18 patients, although there was significant difference on the PGA 1 (p=.006) and 3 (p=.02) months after last treatment (Wilcoxon signed rank test). Patients experienced moderate pain during treatment and mild adverse events. Conclusion : In this trial, blinded PhGA could not confirm the clinical efficacy of 1540-nm nonablative fractional laser in the treatment of hypertrophic scars, but the treatment is safe, and patients judged that the treated part had a better global appearance.

Bullous pyoderma gangrenosum is an atypical, more superficial variety of the classical pyoderma and is often associated with myeloproliferative disorders. We present the case of a patient who presented initially with subcutaneous nodules and who developed bullous lesions afterwards. Histological evaluation showed the presence of neutrophilic infiltrates in both lesions. A few months after the diagnosis of bullous pyoderma gangrenosum, an underlying leukemia was revealed. Our case illustrates the importance of regular blood and bone marrow examinations in patients with atypical bullous pyoderma gangrenosum, resulting in a rapid diagnosis of the underlying disease.

Basal cell carcinoma (BCC) is the most common form of skin cancer worldwide. Different treatment options exist. The efficacy of photodynamic therapy with methyl aminolevulinate (MAL-PDT) has been established in several randomized controlled trials (RCTs). Real life data can differ greatly from data derived from randomized controlled trials (RCTs).To describe the results of a Belgian observational study concerning superficial BCC (sBCC) vis-a-vis clinical and health economic outcomes in order to evaluate the real-life practice of MAL-PDT.This study was a prospective, single-arm, open study conducted at eight dermatological institutions during six months after the first MAL-PDT treatment. Eligible patients had to present with lesions, suitable for MAL-PDT according to Belgian reimbursement criteria. Resource use was collected during the study period. Clinical Response (CR) and Cosmetic Outcome (CO), as well as cost of care were evaluated. A subset analysis of patients with sBCC only was conducted.Ninety patients were identified for the analysis (mean age 65 years; 61% female). The mean number of lesions per patient was 1.6, mostly located on the face, the back and the chest. For the entire period, the mean number of visits to a dermatologist was 4 per patient including two MAL-PDT sessions. The average, cumulative amount of MAL used per treatment was 1,256 mg. Two patients experienced adverse events at the application site, none of them serious; all resolved completely. The CR rate was 89% at the end of the study. The CO was "excellent" or "good" in 96% of the patients. Total cost of care was Euro 289 ($414 U.S.) per patient. Cost per lesion was Euro 195 ($280 U.S.).The results from the real-life practice study confirm the efficacy found in prior, prospective randomized trials. About four visits and less than one tube of MAL are needed for the full treatment of sBCC in one patient.

› The treatment of choice for tattoo removal nowadays is a specific treatment with Q-switched lasers; however, multiple treatments are normally required and may vary between 5 and 20 or more. › Excellent results can be obtained with Q-switched lasers but complete clearance of tattoos is rare and there is no guarantee that any treatment will restore the skin to its original condition. Side effects and complications can occur. › In some indications, adjunctive topical therapy and nonspecific treatment with surgery or ablative lasers can be necessary, more particularly, tattoo granulomas or tattoos with an allergic response. Other indications are resistant tattoos after multiple Q-switched laser treatment sessions and some cosmetic tattoos.

Clinical trials have shown that photodynamic therapy using methyl aminolevulinate (MAL-PDT) is an effective treatment for actinic keratosis (AK), and nodular and superficial basal cell carcinoma (nBCC and sBCC) unsuitable for other available therapies. Economic evaluation models have shown that it is a cost effective intervention as well. The objectives of this prospective, observational, one arm study were (i) to verify in a real-life practice study the results obtained in previous clinical trials with MAL-PDT in the treatment of AK, nBCC and sBCC; (ii) to calculate the real-life cost of treatment and validate predictions from an economic evaluation model. Patients with AK and/or BCC were selected according to Belgian reimbursement criteria for treatment with MAL-PDT. Clinical response, cosmetic outcome and tolerability were assessed. MAL-PDT cost was calculated and compared to published model cost data. Data were collected from 247 patients (117 AK, 130 BCC). A complete clinical response was obtained for 83% of AK (85/102) and BCC (97/116) patients. A good or excellent cosmetic outcome was obtained for 95% of AK patients and 93% of BCC patients. Tolerability was good: only 2 patients withdrew for adverse events. Clinical results were similar to previous studies. Total cost of care per patient was euro 381 for AK, euro 318 for nBCC, and euro 298 for sBCC. Total cost per lesion was euro 58 for AK (identical to model prediction), euro 316 for nBCC and euro 178 for sBCC (both within 20% of model prediction). The clinical results of MAL-PDT in this real-life practice study confirm those demonstrated in previous clinical trials. Costs calculated from this study confirm predicted cost-effectiveness in the original model for MAL-PDT in the management of AK and BCC.

When a biopsy is taken of a suspicious pigmented skin lesion, histological examination is expected to establish the definitive diagnosis. This study evaluated the inter-observer variation of 20 pathologists in the histological diagnosis of a randomly selected set of suspicious pigmented skin lesions (PSLs), by comparing their diagnoses to a reference diagnosis. Overall sensitivity for melanoma was 87%, ranging from 55% to 100% between the observers. Sensitivity was significantly lower for thin (Breslow thickness1 mm) than for thick melanomas (83% versus 97%, p=0.005). Overall melanoma specificity was 94%, ranging from 83% to 100% between observers. Dysplastic naevus was the most important source of false-positive diagnoses, mainly in situ melanomas. Positive and negative predictive values in the given test set were 75% and 97%, respectively. In the case of melanoma, there was quite some variation in measured Breslow thickness. This would have led to a different therapeutic approach in 12% of the readings. Some of the variation seemed to be due to a different interpretation of the presence of a co-existent naevus. In 9% (3/35) of the readings, participants did not agree on the presence of ulceration. These results reflect a tendency to overdiagnose mainly thin melanomas in general histopathological practice. They also demonstrate variation in the assessment of major prognostic factors of melanoma.