Fig. 3
Atypical Skin Lesion – Correlations between Clinical, Dermoscopy, Pathology, and Confocal Microscopy Observations. a Clinical image of a brown, dome-shaped lesion. b Dermoscopy image (20× magnification) shows irregular pigmentation within a central light brown structureless area that is surrounded by clustered brown globules. c A RCM mosaic image (4 × 4 mm2) at the level of the DEJ shows disorganized architecture with focal loss of rete ridge meshwork. Heterogeneous brightness (marked with a yellow dashed square) and a clod pattern at the periphery (marked with a red dashed square) are also observed. d A RCM mosaic image (1 × 1 mm2) of the area inside the yellow dashed square in C at the level of the DEJ shows clusters of cells with nonhomogeneous morphologic features and reflectivity (indicated with yellow asterisks). Dendritic cells enlarged in the interpapillary spaces (indicated with red arrows) and round nucleated cells (indicated with yellow arrows) are also present. e An individual RCM image (0.5 × 0.5 mm2) of the area within the red dashed square in C at the level of the DEJ shows dense and regular nests at the periphery of the lesion. f Histology shows a compound, symmetrical melanocytic proliferation (H&E, 20× magnification) with benign melanocytic nests of varied sizes at the dermal-epidermal junction at the periphery of the lesion. These findings correspond to the RCM finding of a clod pattern (indicated with a red dashed square). In the center of the lesion, nest formation is reduced, corresponding to the heterogeneous brightness observed with RCM (indicated with a yellow dashed square, Fig. 3c). g A higher magnification (200×) image of the intradermal component (H&E) shows that the lesion includes a few isolated large epithelioid cells which are intermingled with an abundance of smaller mature melanocytic cells and foci of adipocyte metaplasia and cystic spaces. The large cells correspond to the round nucleated cells observed with RCM (indicated with yellow arrows, Fig. 3d). h The junctional component is composed of irregular large nests of typical melanocytes (H&E, 200× magnification). The diagnosis is compatible with BIMT. Sequencing additionally revealed this lesion harbors a BRAF gene mutation (p.V600E)