Nævus Pigmentosus (Synonym: Mole.)
Describe nævus pigmentosus.
Nævus pigmentosus, commonly known as mole, may be defined as a circumscribed increase in the pigment of the skin, usually associated with hypertrophy of one or all of the cutaneous structures, especially of the connective tissue and hair. It occurs singly or in numbers; is usually pea-, bean-sized or larger, rounded or irregular, smooth or rough, flat or elevated, and of a color varying from a light brown to black; the hair found thereon may be either colorless or deeply pigmented, coarse and of considerable length. It is, as a rule, a permanent formation.
Name the several varieties of nævus pigmentosus met with.
Nævus spilus, nævus pilosus, nævus verrucosus, and nævus lipomatodes. So-called linear nævus might also be considered as belonging in this group.
What is nævus spilus?
A smooth and flat nævus, consisting essentially of augmented pigmentation alone.
What is nævus pilosus?
A nævus upon which there is an abnormal growth of hair, slight or excessive.
What is nævus verrucosus?
A nævus to which is added hypertrophy of the papillæ, giving rise to a furrowed and uneven surface.
What is linear nævus?
Linear nævus is a formation usually of a verrucous character, more or less pigmented, sometimes slightly scaly, occurring in band-like or zoster-like areas, and, as a rule, unilaterally.
What is nævus lipomatodes?
A nævus with excessive fat and connective-tissue hypertrophy.
State the etiology of nævus pigmentosus.
The causes are obscure. The growths are usually congenital; but the smooth, non-hairy moles may be acquired.
Give the pathology of nævus pigmentosus.
Microscopical examination shows a marked increase in the pigment in the lowest layers of the rete mucosum, as well as more or less pigmentation in the corium usually following the course of the bloodvessels; in the verrucous variety the papillæ are greatly hypertrophied, in addition to the increased pigmentation. There is, as a rule, more or less connective-tissue hypertrophy.
What is the treatment of nævus pigmentosus?
In many instances interference is scarcely called for, but when demanded consists in the removal of the formation either by the knife, by caustics, or by electrolysis. This last is, in the milder varieties at least, perhaps the best method, as it is less likely to be followed by disfiguring cicatrices. In nævus pilosus the removal of the hairs alone by electrolysis is not infrequently followed by a decided diminution of the pigmentation. In recent years both liquid air and carbon dioxide have also been used successfully in the removal of these growths. Pigmented nævi, which show the least tendency to growth or degenerative change, should be radically removed, as they not infrequently lead to carcinomatous and sarcomatous growths.