Clinical and Dermatoscopic Signs of Micromelanoma - A Review of the Literature

Abstract

Introduction: Micromelanoma, also called a small-sized melanoma, in the scientific literature is commonly defined as a skin melanoma with a diameter of 3 mm or less, although definitions of 5 mm or less can also be found.

Objectives: The aim of this study was to identify the clinical and dermatoscopic features that characterize skin micromelanomas.

Materials and Methods: The study was carried out by searching relevant articles using keyword “micromelanoma” in the following electronic databases – PubMed, Wiley, Scopus, Web of science, ScienceDirect, EBSCOhost, and Google Scholar. The search was performed in the period from January 20^th, 2022, to January 31^st, 2022. The search had a limit of English language.

Results: According to the published literature, micromelanomas are most often diagnosed in women, since in reviewed studies 43 – 81.8% of patients were women. People diagnosed with micromelanoma are mostly in the age group of 40 to 59 years. Clinically micromelanomas are most frequently seen as dark or light brown macules in diameter of 3 – 4 mm located on the lower extremities and as lesions that had developed de novo. The most common diagnostic methods used for micromelanoma diagnostics are physical skin examination and dermatoscopy – polarized light and nonpolarized light. The most widely used diagnostic dermatoscopic algorithm is the 7 – point checklist. Diagnostic accuracy shown for dermatoscopic algorithms is in the range of 48.2 – 65.9%, showing that not all micromelanomas can be diagnosed with diagnostic dermatoscopic algorithms and other characteristics must be considered. The dermatoscopic pattern for micromelanomas is variable – spitzoid, globular, reticular, and structureless, of which spitzoid is the most common. The most common melanoma-specific dermatoscopic signs seen in micromelanomas are irregular dots/globules (25.0 – 88.4% of micromelanomas), atypical network (40.0 – 77.0% of micromelanomas), atypical blotches (16.6 – 38.4% of micromelanomas), and pseudopods (3.4 – 46.0% of micromelanomas). Less frequently other melanoma specific dermatoscopic features – regression, blue – white veil and asymmetric multicomponent dermatoscopic pattern can be observed. Micromelanomas often present asymmetry in structure and color and frequently have two colors dermatoscopically. Micromelanomas rarer than larger melanomas have atypical vessels – dotted, linear, or polymorphous (3.8 – 32.0% of micromelanomas).

Conclusions: Micromelanoma can develop in people of any age and gender, but most commonly it develops after the age of 40 and in women. Micromelanoma develops mainly as a de novo lesion on the lower extremities and has a diameter of 1 to 5 mm at the time of presentation. Dermatoscopically, micromelanomas often have melanoma-specific dermatoscopic features, and therefore dermatoscopy aids in diagnosing micromelanoma.