19. Nаevus pigmentosus.

19. Nаevus pigmentosus.
Pigment nevus is congenital or acquired benign neoplasm originating from dendritic melanocytes localized in the basal layer of epidermis. In this case it is seen as an example of impaired metabolism of aboriginal pigment melanin produced by dendritic melanocytes. Nevus can occur in various forms but the most common are: border, dermal, complex, spitz nevus, and nevus dizplastichen. In this case demonstrates dermal nevus. In melanocytes proliferate as it shaped nests in the epidermis. Usually they contain brown granules of melanin, the pigment but may not be evident. The nests are composed of uniform round or polygonal cells drained, with homogeneous or slightly granular cytoplasm and large round or oval nucleus. Nevus can give early malignant pigmented tumors - malignant melanoma.