Benign mole. Light micrograph of a section through a compound benign melanocytic naevus (benign mole). The surface of the skin is across top. The melanocytic tissue is the rounded areas across top, located in the basal layers of the epidermis, with the same tissue in the dermis (across bottom). The stained areas (dark spots) are cell nuclei. Moles are caused by an abnormality or proliferation of melanocytes, the skin cells that produce the pigment melanin. Most moles are harmless but they can turn cancerous. A compound naevus is a transition between the junctional form (C006/6060) and the intradermal form (C006/5975).