A melanocytic nevus is a type of lesion that contains nevus cells.[
Some sources equate the term mole with "melanocytic nevus".] Other sources reserve the term "mole" for other purposes.
According to the American Academy of Dermatology, the majority of moles appear during the first two decades of a person’s life, while about one in every 100 babies is born with moles. Acquired moles are a form of benign neoplasm, while congenital moles, or congenital nevi, are considered a minor malformation or hamartoma and may be at a higher risk for melanoma.] A mole can be either subdermal (under the skin) or a pigmented growth on the skin, formed mostly of a type of cell known as a melanocyte. The high concentration of the body’s pigmenting agent, melanin, is responsible for their dark color. Moles are a member of the family of skin lesions known as nevi.
Similarly as in humans the canine lesions are also found in the elderly. As the cohesiveness of the epidermis begins to deteriorate the cells can mutate to form any number of skin disorders.