Pigmented nevus

Pigmented nevus

Pigmented nevus (Nevus), also known as nevus cell nevus and melanocytic nevus, is a benign disease characterized by changes in the color of the skin and mucous membranes due to the proliferation of nevus cells and the production of pigments. Pigmented nevus maintains a stable state for a long time and will not recur after surgical resection; but beware of a very small number of pigmented nevus that undergo malignant transformation.

Western medical name: Pigmented nevus

English said: Nevus

Department: Otology-Dermatology

Incidence site: skin, mucous membrane

Main symptoms: Localized color change of skin or mucous membrane

Main cause: Unknown cause

Infectious: non-infectious

Whether to enter the medical insurance: Yes

Introduction to the disease

Pigmented nevus and pigmented spots are collectively called pigmented nevus, which is a localized pigmented abnormal lesion. Pigmented spots, also known as non-cellular pigmented nevus, are pigmentation of the skin without tumor cells, such as freckles, age spots, etc.; unlike pigmented spots, pigmented nevus is a proliferation of nevus cells, so it is also called cellular nevus. Clinically, pigment spots are difficult to distinguish from pigmented nevus. The nevus cells in pigmented nevi are developed from neural crest precursor cells, which can produce pigment. Pigmented nevus is a benign disease, it maintains a stable state for a long time, and it is very rare to have malignant changes. Pigmented moles are mostly found on the skin of the face and neck, and occasionally on the oral mucosa.

Disease classification

(1) Intradermal nevus: the most common. It usually occurs on the facial skin and hairline, and varies in size, up to a few centimeters in the larger ones, and even affects the hemi-face of the neck. The skin is raised, hairy, light brown or light black, with clear borders. Composed of small mole cells. The nevus cells nest in the connective tissue under the epithelium (that is, in the dermis). The epithelial layer on the surface of the nevus cell nest is normal. Generally, cancer does not occur.

(2) Junctional nevus: It can evolve from intradermal nevus, or it can occur alone. It can occur at any age, but it is more common in infants and young children. The lesion is flat, brown-black or blue-black, with clear or unclear borders. Generally, the volume is small, mostly within a few millimeters. The surface is smooth and hairless. It can remain unchanged for a long time, and a few can subside on its own, and it is more prone to malignant changes. It is composed of large nevus cells. Half of the nevus cell nest is in the bottom layer of the epidermis, and the other half is in the superficial connective tissue under the epidermis, that is, in the superficial dermis. There may be cancer.

(3) Compound mole: It is more common in children. Most of the lesions protrude slightly from the skin surface, and a few are papilloma-like changes. They are generally hairless. They can increase in size and darken with age. The junctional nevus part of the compound nevus can be malignant. The pathological feature is that during the process of nevus cells entering the dermis, intradermal nevi and residual junctional nevi are often present at the same time, which is a mixed form of intradermal and junctional nevi.

Clinical manifestations

Prone group

Pigmented nevi can occur at any age, and most of them appear the day after tomorrow.

Disease symptoms

Pigmented moles are asymptomatic. If there are symptoms, be alert for malignant changes. It appears as black, yellow-brown or blue, flat or slightly raised spots or plaques; there are a few colorless pigmented moles.

Disease hazards

Very few pigmented moles will undergo malignant changes and become malignant melanomas. It has been reported that about 50% of malignant melanomas originate from pigmented nevi. Pigmented nevus appears with concomitant symptoms and changes in color and texture in a relatively short period of time. It must be vigilant and surgically removed as soon as possible. The following clinical changes appear, suggesting that pigmented moles may become malignant: ①pain, itching; ②increased size or small "satellite moles" around them; ③color changes with varying shades; ④inflammatory blushes around; ⑤pigmented nevi appear Induration or festering.

Disease identification

Malignant melanoma: The early stage of skin malignant melanoma is skin pigmented nevus. When malignant transformation occurs, the original pigmented nevus rapidly enlarges, itching, ulcers and even ulcers and hemorrhages, the pigment becomes darker or dark brown, and the edges become irregular. , Satellite summary of hemochrome around the lesion. Mucosal malignant melanoma is blue-black or colorless (non-pigmented malignant melanoma). The lesions grow faster, are prone to ulcers, and are often accompanied by bleeding.

Disease treatment

The vast majority of pigmented moles do not require treatment. Facial moles can be removed surgically when they affect their appearance. When the area is large, the resection can be performed in stages, or free skin grafting or transfer of adjacent skin flaps can be performed after one resection. If malignant moles are suspected, surgical procedures should be used to remove all at once for biopsy; surgical incisions should be made on the normal skin outside the borders of the moles. For example, after a small mole is removed, the skin can be peeled off the edge of the wound and the wound can be directly drawn and sutured.

Disease prognosis

No recurrence after surgical resection

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