Skin mole. Light micrograph (LM) of a section through a naevus, a type of skin mole. This pigmented naevus is produced by abnormal clustering of pigment cells (melanocytes brown) in the skin. At top are loose cornified layers on the surface of the skin. The epidermis is immediately below this, followed by the dermis. Throughout this region there are clusters of brown melanocyte pigment cells. Naevi are harmless, but on rare occasions can become cancerous. Magnification: x150 when printed at 10 centimetres wide. Human tissue.