Vania Lukoviek, Nuria Ferrera, Sebastian Podlipnik, Sümeyre Seda Ertekin, Cristina Carrera, Alicia Barreiro, Marion Chavez-Bourgeois, Francesca Perino, Mauricio Ortiz-Ruiz, Susana Puig, Josep Malvehy
DOI: 10.2340/00015555-3436

Numerous dermoscopic structures for the early detection of melanoma have been described. The aim of this study was to illustrate the characteristics of dermoscopic structures that are similar to blotches, but smaller (termed microblotches), and to evaluate their association with other well-known dermoscopic structures. A cross-sectional study design, including 165 dermoscopic images of melanoma was used to define microblotches, and 241 consecutive images of naevi from the HAM10000 database, were studied to evaluate the prevalence of this criterion in both groups. Microblotches were defined as sharply demarcated structures ≤1 mm, with geographical borders visible only with dermoscopy. Microblotches were present in 38.7% of the melanomas and 6.7% of the naevi. Moreover, microblotches were associated with an odds ratio (OR) of malignancy of 5.79, and were more frequent in invasive melanoma than in the in-situ subtype (OR 2.92). Histologically, they correspond to hyperpigmented parakeratosis or epidermal consumption. In conclusion, microblotches are related to melanomas. This finding could help dermatologists to differentiate between naevi and melanomas.

This study evaluated 165 consecutive well-documented dermoscopic images, with the aim of illustrating the characteristics of a dermoscopic structure similar to blotches, but smaller (termed microblotches), and to evaluate their association with other dermoscopic structures. After evaluation by expert dermatoscopists, microblotches were defined as superficial millimetric structures with geographical borders, only visible under dermoscopy. The study also evaluated 241 consecutive naevi from the HAM10000 database and found that microblotches were present in only 6.7% of naevi cases, compared with 38.7% of cases of melanoma in our cohort (odds ratio; OR 5.79). Moreover, microblotches were more frequently observed in invasive melanoma (OR 2.92), and their presence was associated with other dermoscopic criteria of poor prognosis. Histologically, they are correlated with hyperpigmented parakeratosis or consumption of the epidermis. In conclusion, microblotches are correlated with invasive pigmented melanomas.