Dermoscopy comparative approach for early diagnosis in familial melanoma: influence of MC1R genotype.

BACKGROUND: MC1R polymorphisms interact with CDKN2A mutations modulating melanoma risk and contribute to a less suspicious clinical and dermoscopic appearance of melanomas. Different strategies, including dermoscopic comparative approach and digital monitoring, are used for the melanoma diagnosis in this context. OBJECTIVE: To analyse the diagnostic accuracy of the morphologic approach and comparative approach in dermoscopy, and to detect melanoma in familial melanoma (FamMM) patients according to different genetic backgrounds. METHODS: Two independent readers evaluated 415 lesions belonging to 25 FamMM: 26 melanomas (62% in situ, 36% early invasive) and 389 naevi, blinded for dermoscopic and histopathologic diagnosis, following two different steps. First step-Randomized: all lesions were randomly located in one single folder. Second step-Comparative approach: the lesions were clustered by patient. Sensitivity, specificity and number needed to excise (NNE) for melanoma diagnosis were calculated for both diagnostic strategies. Sensitivity and specificity were also assessed regarding the genetic background. RESULTS: The comparative approach showed lower sensitivity compared to the morphologic approach (69.2 and 73.1 vs. 76.9 both readers) but better specificity (95.9 and 95.1 vs. 84.3 and 90.2, respectively). NNE was better in the comparative approach. The readers had more difficulties diagnosing lesions from CDKN2A mutation carriers with red hair colour (RHC) MC1R variants. CONCLUSION: The comparative approach can be useful in high-risk patients to decrease the NNE. Early melanomas in CDKN2A carriers with RHC polymorphisms are more difficult to diagnose even with the comparative approach and benefit from the detection of changes during digital dermoscopy monitoring for early diagnosis.

Dermoscopic patterns of 158 acral melanocytic nevi in a Latin American population.

BACKGROUND: Melanocytic nevi are frequently found on acral volar skin. Differentiation between nevi and melanoma is essential and sometimes difficult, although dermoscopy has enabled a more specific diagnosis of pigmented lesions. Dermoscopic patterns of lesions on acral volar skin have mostly been described in European and Asian populations. The Latin American population is heterogeneous, and particularly so in the case of Uruguayans, who largely descend from 3 distinct populations. OBJECTIVE: To describe dermoscopic patterns of acral melanocytic nevi and evaluate their applicability in a Latin American population in Uruguay. PATIENTS AND METHODS: This was an observational, descriptive, cross-sectional study conducted by 2 dermatologists from 4 dermatology clinics in Uruguay. Uruguayan patients older than 18 years with acral melanocytic nevi were included. Digital dermoscopic images were captured and jointly analyzed by 2 investigators. RESULTS: A total of 158 acral volar nevi in 80 patients were analyzed. The most-prevalent pattern was the parallel furrow pattern (51.3% of nevi), followed by the latticelike pattern (13.3%), the homogeneous pattern (12.7%), the globular pattern (9.5%), the fibrillar pattern (7%), the globulostreaklike pattern (3.8%), and the nontypical pattern (2.5%). The reticular and transition patterns were not observed in our population. CONCLUSIONS: The parallel furrow pattern, followed by the latticelike and homogeneous patterns, was the most-prevalent pattern in acral melanocytic nevi in the Uruguayan population. The fibrillar pattern was found exclusively on the soles. No new dermoscopic patterns were observed. The patterns described in Asian and European literature apply to our population.

CDKN2A mutations in melanoma families from Uruguay.

BACKGROUND: Familial melanoma, a cluster of several cases within a single family, accounts for approximately 10% of cases of melanoma. Hereditary melanoma is defined as two or more first-degree relatives having melanoma. A member of a melanoma-prone family has a 35-70-fold increased relative risk of developing a melanoma. Genetic susceptibility is linked to the major susceptibility genes CDKN2A and CDK4, and the minor susceptibility gene MC1R. OBJECTIVES: To determine the clinical and genetic characteristics of cutaneous melanoma in melanoma-prone families from Uruguay. METHODS: We studied 13 individuals from six melanoma-prone families living in Uruguay. Phenotype, familial and personal history were recorded. Molecular screening of CDKN2A and CDK4 was done by polymerase chain reaction-single strand conformational polymorphism analysis. The MC1R gene was sequenced. RESULTS: Mutations in CDKN2A were detected in five of six families: c.-34G>T, p.G101W and p.E88X. A novel germline mutation p.E88X, associated with hereditary melanoma in two unrelated families, is described. We hypothesize that a founder effect occurred probably in the Mediterranean region. No mutations in CDK4 were detected. Six different MC1R variants, all previously reported, were present in Uruguayan families. CONCLUSIONS: The overall rate of deleterious CDKN2A mutations in our familial melanoma pedigrees, even though the sample size is small, was considerably higher (83%) than the often quoted range.