Diagnosis of pigmented skin lesions: how to recognize a malignant melanoma

An accurate answer to the clinical question of whether a pigmented skin lesion has become a malignant melanoma or not is difficult because of the clinical variability of this lesion. Because of the low incidence of 2400 new melanoma cases each year in The Netherlands, a general practitioner only sees one new case every 3-4 years. The best way to distinguish between a benign lesion and a malignant melanoma is the combined use of several criteria, such as in the ABCD-formula: asymmetry, border irregularity, colour variation and a diameter > 6 mm. Dermatoscopical examination, provided that the technique is used by well-trained and experienced physicians, is a valuable adjunct to clinical examination. A pigmented lesion should always be excised if there is not enough convincing evidence to exclude its malignant nature. Histological classification of pigmented lesions may prove difficult because of morphological overlap between benign and malignant melanocytic tumours.     

Dermatoscopy: an asset in the clinical assessment of pigmented skin lesions

Dermatoscopy is a non-invasive technique for the clinical diagnosis of pigmented skin lesions: a simple contact skin-surface microscope with a 10-fold magnification is used; the application of oil makes the horny layer translucent, as a result of which several additional criteria become available for the diagnosis of pigmented lesions. The evaluation is based on an algorithm involving asymmetry, border, colour and differential structure; another type of evaluation involves pattern analysis (global assessment, detailed assessment, assessment of the pigment network). The evaluation of these criteria requires formal training, after which the diagnostic skills of dermatologists have been found to increase; in non-dermatologists these skills decreased. Dermatoscopy has become an indispensible aid in clinical dermatology.     

The diagnostic accuracy of Danish GPs in the diagnosis of pigmented skin lesions

BACKGROUND: The GP often has a primary function in assessing pigmented skin lesions in Denmark. No data are available on the diagnostic accuracy of this process. OBJECTIVE: We aimed to study the sensitivity, specificity and positive prognostic value of the diagnosis made by 27 trained or trainee GPs. METHOD: We tested the diagnostic accuracy of the viewing of colour slides of pigmented skin lesions under standardized conditions at a seminar on skin cancer. Diagnostic accuracy was determined only for the clinically relevant diagnosis of benign or malignant. RESULTS: The median diagnostic accuracy (sensitivity) for the group as a whole was 0.75 (95% CI 0.65-0.80), the specificity was 0.70 (95% CI 0.68-0.79) and the positive predictive value 0.70 (95% CI 0.62-0.77). CONCLUSION: These values are comparable with previously published figures for trainee dermatologists, and it is therefore concluded that ongoing interest rather than basic training is the major determinant for clinical acumen.     

Diagnosis of pigmented skin lesions by epiluminescence microscopy: determinants of accuracy improvement in a nationwide training programme for practical dermatologists

BACKGROUND: The poor accuracy of the clinical examination of pigmented skin lesions (PSLs) is a major limitation of secondary prevention strategies for cutaneous melanoma (CMM). In the last few years, the epiluminescence microscopy (ELM) technique has been used increasingly as an adjunct to clinical examination in the dermatology practice. Although the question of training has emerged as a priority, the diffusion, the effects, and the correlates of educational programmes in ELM have seldom been studied. METHODS: Thirty ELM images of PSLs (11 CMMs, 14 melanocytic nevi (MN), and 5 nonmelanocytic lesions (NMLs) each matched with the corresponding clinical or plain photographic image were independently diagnosed before and after a one-day workshop by 83 Italian dermatologists participating in a nationwide educational programme on ELM. The original histology diagnosis was assumed as a gold standard. The overall effect of training on a set of accuracy measures by PSL type was evaluated. The association of the professional sector (public/private), number of years of general experience in dermatology (1-10/>10), average weekly number of PSLs seen (< or =10/11-20/>20), routine use of ELM (no/yes), and area of residence (northern/southern Italy) with the mean number of PSLs correctly diagnosed before and after training was evaluated with the general factorial analysis of variance. The factors associated with improvement between the two tests were evaluated with the analysis of variance for repeated measures. RESULTS: Compared with pretraining data, the average percentage of exact diagnosis increased significantly for all PSLs (CMMs, 72% vs 55%; MN, 68% vs 64%; NMLs, 67% vs 58%; total lesions combined, 69% vs 60%). Baseline as well as final accuracy were independent from the professional sector and the years of experience but were greater among those subjects who reported >20 PSLs per week compared with the reference group (< or =10 PSLs). The routine use of ELM was associated with a slight advantage in pretraining accuracy. The area of residence was the strongest determinant of baseline as well as final accuracy. The effect of training was independent from all factors studied with the exception of the area of residence with a 13% increase in the frequency of exact diagnosis in northern Italy (from 66-79%) and 6% in southern Italy (from 55-61%). CONCLUSIONS: Though insufficient in absolute terms, a measurable increase in ELM accuracy can be achieved even with intense training sessions of short duration. Medical education to ELM in southern Italy should be a priority.     

Are malignant melanoma time trends explained by changes in histopathological criteria for classifying pigmented skin lesions?

The incidence of malignant melanoma in developed countries has been rising rapidly in recent years. Its causes and the reasons for this trend are uncertain. Changes in histopathological criteria for classifying pigmented skin lesions could explain the rising incidence rates. With support from the International Agency for Research on Cancer, this hypothesis is explored but not substantiated for time trends in the South Western Region, United Kingdom.     

A woman with skin lesions in a tattoo

A healthy 32-year-old woman presented with red papules in tattoos on the right upper arm and right ankle as well as on non-tattooed skin of the right knee, existing since 3 months. Histopathological examination of skin biopsies showed granulomatous inflammation, suggestive for sarcoidosis. An X-ray and CT-scan of the thorax showed hilar lymphadenopathy suggestive of sarcoidosis. Skin lesions in tattoos can be the first symptom of systemic sarcoidosis. Further investigation in these cases is recommended.     

Arsenic exposure and age and sex-specific risk for skin lesions: a population-based case-referent study in Bangladesh

BACKGROUND: The objective of this population-based case-referent study in Matlab, Bangladesh, was to assess the susceptibility to arsenic-induced skin lesions by age and sex, in a population drinking water from As-contaminated tube wells. METHODS: Identification of As-related skin lesions was carried out in three steps: a) screening of the entire population > 4 years of age (n = 166,934) by trained field teams; b) diagnosis of suspected As-related cases by physicians; and c) confirmation by experts based on physicians' records and photographs. A total of 504 cases with skin lesions were confirmed. We randomly selected 2,201 referents from the Matlab health and demographic surveillance system; 1,955 were eligible, and 1,830 (94%) were available for participation in the study. Individual history of As exposure was based on information obtained during interviews and included all drinking-water sources used since 1970 and concentrations of As (assessed by atomic absorption spectrophotometry) in all the tube wells used. RESULTS: Cases had been exposed to As more than referents (average exposure since 1970: male cases, 200 microg/L; female cases, 211 microg/L; male referents, 143 microg/L; female referents, 155 microg/L). We found a dose-response relationship for both sexes (p < 0.001) and increased risk with increasing socioeconomic status. Males had a higher risk of obtaining skin lesions than females (odds ratio 10.9 vs. 5.78) in the highest average exposure quintile (p = 0.005). Start of As exposure (cumulative exposure) before 1 year of age was not associated with higher risk of obtaining skin lesions compared to start of As exposure later in life. CONCLUSIONS: The results demonstrate that males are more susceptible than females to develop skin lesions when exposed to As in water from tube wells.