Page:Skin Diseases of Children.djvu/85



The term naevus signifies a spot or blemish upon the skin. It is usually a congenital affection, although certain forms of skin disease to which the term nsevus is commonly applied may occur in youth or later in life. Many nsevi, especially of the pigmented and hairy variety, exist at birth, but are almost imperceptible, and only become noticeable when they develop, as they are apt to do, after the age of puberty.

The term nsevus includes affections of widely different pathological character in which hypertrophy is the only common element. They may be classed as iibrous, pigmented,. hairy, and vascular nsevi. The fibrous or hypertrophic nsevus frequently occurring upon the face in the form of a small, rounded, and non-pigmented tumor or mole is peculiar to adult life, but the pigmented and hairy forms of nsevus are common in childhood and often require treatment at an early age.

Naevus pigmentosus is the result of an excessive deposit of pigment granules in the mucous layer of the skin. It differs from a freckle or chloasmic discoloration (which are acquired affections and liable to disappear spontaneously) in appearing at or soon after birth and being permanent. The pigmentary nsBAois varies greatly in color and size. It may be yellowish or of a deep-brownish hue. It may be no larger than a pin's head, in which case it is apt to be multiple, or it may cover a portion of the body larger than the hand. The face, neck, and back of the hand are favorite sites, but it may appear on the trunk and extremities. It is sometimes flat and smooth, like a freckle, but may become elevated and warty in certain cases, when the term nsevus verrucosus is applicable.

In many cases of extensive pigmentary nsevus, whether smooth or elevated, "we find a growth of fine or coarse hair upon the surface. When this is more marked than the pigmentation the affection is called nsevus pilosus. The hairy nsevus is often