What causes congenital melanocytic nevus?

We all have moles on various parts of our body to varying degrees, they may be congenital or acquired. Congenital giant pigmented nevus is a relatively special type of nevus. It is not hereditary, but it is usually distributed on the scalp, back, arms and other parts of the body, and the area is very large, which greatly affects the appearance. This congenital giant pigmented nevus is often present at birth. The color of the nevus is relatively dark and it is accompanied by hair growth. However, the range of the nevus may decrease or become lighter as the age increases. It may be caused by the environment, diet, nutrition and mood of the mother during pregnancy. So what exactly causes congenital melanocytic nevus?

1. Introduction

Giant congenital pigmented nevus is a special type of congenital naevus cell nevus that is not inherited and can exceed 20 cm in diameter. Lesions may cover the entire head, shoulders, limbs, or most of the trunk; 10% to 13% of patients may develop malignant melanoma.

2. Symptoms and signs

1. Present at birth. The lesions cover the entire head, shoulders, limbs, or most of the trunk. They are darker in color, often brown or black, with a sense of infiltration, raised above the skin surface, with small papillary nodules or wart-like hyperplasia on the surface (Figures 1-4). There are often hairs, which are thicker, darker, and more numerous than normal. They may increase with age, and satellite-like lesions can be seen scattered around the periphery.

2. In lesions occurring on the back, the hair is often arranged in a whorl shape with the midline as the center. In the spine, it may be accompanied by spina bifida or meningeal herniation. In lesions occurring on the scalp, there are gyral lines on the surface, which are called giant gyral nevus. It may be accompanied by leptomeningeal melanocytoma, and manifest as epilepsy, mental retardation, and other localized neurological dysfunctions. Other complications may include café au lait spots, fibromas, lipomas or neurofibromas.

3. It becomes more obvious after childhood, but may stop growing and may become lighter in color (Figure 3). Malignant melanoma may occur in 10% to 13% of patients, and it can occur in people of all ages.

3. Treatment

The traditional treatment method is to remove the diseased tissue in stages and cover the wound with skin grafting. However, this method has poor postoperative effects and will leave large linear scars and donor site scars. In addition, contracture of the skin graft area and donor area may have an adverse effect on the growth and development of the child.

It is more effective to treat melanocytic nevus by removing it, as it can preserve the regenerative normal epithelial cells and permanently repair the wound without skin grafting. This treatment method is particularly useful for treating giant congenital nevi. It not only avoids taking skin from normal tissue to cover the surgical wound left after the removal of the giant nevus, but also because the surgical cutting layer is shallow, generally no obvious scars will be left after the operation.