Fig. 2

Morphological features of case 2. a An ill-defined, heterogeneous, brownish lesion is present on the surface of the foreskin (red arrowhead). b Below the mucosa, an atypical melanocytic proliferation is visible. The melanocytes form irregular nests and are present at multiple levels of the mucosa [black arrowheads] (H&E stain, 100x). c The cytological atypia is severe, with noticeable epidermal thinning (H&E stain, 200x). d SOX-10 diffusely labels the tumor cells and highlights the pagetoid spread (SOX-10 immunohistochemistry, 100x). The inset demonstrates the diffuse PRAME expression of the tumor cells (PRAME immunohistochemistry, 100x).