Pigment Nevus

Conception

It belongs to benign tumor. Melanocyte concentrates in parts during abnormal migration from neural crest to the epidermis.

Clinical feature

There are three different types according to their clinical feature and histopathology:
1. Junctional nevus : a diameter of several mm to several cm different shades of brown green, black spots of pigmentation, smooth, hairless, but can also be elevated, it can happen in any part of the body, no incidence of sex difference.
2. Hybrid nevus: clinical feature similar to the junction of nevus but higher in the skin.
3. Intradermal nevus:
3.1. Ranging from several mm to several cm in diameter;
3.2. It occur at any part of the body，most in the head and neck;
3.3. The color is brown, blue green, black or skin color;
3.4. Diameter less than 1cm and surface with hair;
3.5. Hemispherical elevate and papillary tumor with pedicled damage pigmented nevus;
3.6. No conscious symptoms, no self-healing tendency.

Histopathology

1. Junctional nevus: The basal layer of epidermis have nevus cell nest, a large amount of melanin in nevus cell.
2. Hybrid nevus is similar to the junctional nevus, the basal layer of epidermis have nevus cell nest, but it was stretched into epidermis which with little or no inflammatory infiltration (a large amount of melanin in nevus cell of epidermis, less or no melanin in dermis.)
3. Intradermal nevus: nevus cells look like nest or cable located in the dermis, buried in collagen tissue without or little melanin.

Method of treatment

Refer to Ota's nevus, but we need notice that the treatment of junctional nevus with Qswitched ND: YAG laser and treatment of hybrid nevus and intradermal nevus with CO2 laser and pre - operative anesthetic, no matter what treatment method, thoroughly eliminate nevus cell is the key to a successful treatment.