Figure 1.

Man, 54 years; a severely atypical melanocytic tumor of the abdomen characterized by a flat pigmented area with an eccentric nodule (A). On dermoscopy, the flat area is typified by a prominent and focally irregular pigment network, whereas the nodular area is characterized by an atypical vascular pattern (B). Histopathologically, the tumor is strikingly asymmetric (C; hematoxylin–eosin, ×25), with a broad highly cellular “shoulder” composed by junctional melanocytes arranged in irregular nests and in single unit (D; hematoxylin–eosin, ×400); the severely atypical junctional component spans above the dermal nodule, the latter being characterized by a lymphoid cell infiltrate (E; hematoxylin–eosin, ×250) and nests of nevocytes intermingled with moderately pleomorphic epithelioid melanocytes with “inclusion-like” cytoplasms (F; hematoxylin–eosin, ×400); all the melanocytic components of this tumor were BRAFv600e mutated protein positive (not shown) and only the dermal epithelioid cell component disclosed loss of the nuclear expression of BAP1 (G; ×250). The tumor was interpreted as an early melanoma developing as a neoplastic progression of a common nevus and not as a progression of a BIN.