A mole or melanocytic naevus is a small spot of darkened pigment on the skin, which forms where there is a high concentration of melanin. They are a member of the family of skin lesions known as naevi. In biology, pigment is any material resulting in color in plant or animal cells which is the result of selective absorption. ... Model of the layers of human skin In zootomy and dermatology, skin is an organ of the integumentary system; which is composed of a layer of tissues that protect underlying muscles and organs. ... Melanin is a pigment ranging from brown to black in hue found in animals and plants. ... Skin Lesions can include moles, cysts, warts or skin tags. ... A nevus is a general term that refers to a number of different, usually benign, pigmented lesions of the skin. ...

Moles are usually circular or oval and not very large. Most children are born with moles, and almost everyone has at least one or two moles on their bodies, some more than others.

Sudden and unexpected changes in skin moles (e.g. bleeding, irritation, darkening, sudden growth) can be a sign of skin cancer so they need to be watched carefully. If a mole appears suspicious, it can be biopsied and checked for signs of malignancy. In medicine (dermatology), there are several different types of cancer referred to under the general label of skin cancer. ... A biopsy (in Greek: bios = life and opsy = look/appearance) is a medical test involving the removal of cells or tissues for examination. ... When normal cells are damaged or old they undergo apoptosis; cancer cells, however, avoid apoptosis. ...