Melanocytic nevus, pigmented nevus
What is it?
It is a benign tumor composed of melanocytes, the cells that produces melanin (pigment that gives color to the skin). They are popularly known as moles and may be present at birth or arise over the years.
Characteristics and symptoms
They usually appear as small spots, brown or black, that may remain flat or, in time, increase in thickness, forming elevated lesions (photo below).
The higher they become, the color tends to become clearer over the years until the color is similar to the surrounding skin (photo below).
There is a form of melanocytic nevus called congenital melanocytic nevus, which, in some cases, may be very large, forming an elevated, rough, brown or black lesion, usually covered with hair. When they reach very extensive areas of the body they are called giant congenital nevus.
Another presentation is the dysplastic nevus, in which the color is not uniform and can vary from pink to black, have larger size than usual moles and irregular edges. Some acquire the aspect of "fried egg" with its center darker and elevated. They can exist in large numbers in the same person and occur in more than one family member.
Halo nevus is a melanocytic nevus surrounded by a depigmented area. This depigmentation arises due to an inflammatory reaction against the nevus cells, which also affects the melanocyte cells that surround the nevus. This process can lead to total disappearance of the nevus and subsequent skin repigmentation.
Another form of presentation is nevus spilus when multiple tiny lesions are superimposed over a light brown stain.
In most cases, there is no need for treatment, but some pigmented nevi may undergo malignant transformation process, giving rise to malignant melanoma, especially dysplastic nevi. If there is suspicion of transformation, surgical excision is indicated.
Melanocytic nevi that are increasing in size, changing color, bleeding or with any other symptons may be in process of malignancy and should be evaluated by a dermatologist as soon as possible.
When treatment is for aesthetic reasons, it may be used the surgical techniques of shaving or excision and suturing to remove the nevus. In cases of suspected transformation, the nevus should be removed by excision and suturing.
- Malignant melanoma
- Solar lentigo