Some Important Facts About Junctional Nevus
A junctional nevus sounds like a rather obscure medical term, but it is actually quite simple to decode. A nevus is simply the medical term for what is more commonly known as either a mole or a birthmark. Junctional refers to the location of the nevus (mole), which is found at the junction of two layers of skin: the outer epidermis, and the inner dermis.
There are three types of common moles: junctional, compound, and dermal. A mole is a group of melanocytes, and the classification of a mole depends on the location of its melanocytes in relation to the layers of the skin. Junctional nevi are commonly associated with children, but it has been found that they are equally as common in elderly patients. A mole becomes a compound nevus when some of the mole's cells move into the dermis layer of skin. It becomes a dermal nevus when all the mole's cells are in the dermis layer. The classification of mole is related to the mole's stage of development, which is why junctional nevi are common in children, while compound and dermal nevi are almost exclusively found in adults.
A junctional nevus is generally fairly easy to recognize. While a dermal nevus is usually elevated, a junctional nevus tends to be flat or only slightly raised. It is usually a uniform brown or tan color, rather than consisting of varied pigmentation. Although it can be any of a range of browns, junctional nevi tend to be some of the darkest brown moles. You can see the lines and other markings of your skin on the junctional nevus, so it essentially looks like just a pigmented area of skin. Its borders are symmetrical, and it is a round or oval shape ranging in size from .1 to .6 centimeters. Junctional nevi are rarely present at birth. They are most common on palms, soles of the feet, and genitalia, and usually develop on the skin sometime after age 2.
In many instances, a junctional nevus will develop into a compound nevus during adulthood, when some cells migrate into the dermis layer of skin. Consequently, a junctional nevus changes appearance with age, as it proceeds through a mole's stages of development and the melanocytes migrate further from the epidermis, or surface layer of skin, down into the dermis. It can sometimes be difficult to tell if this change in appearance is due to a natural progression in the life of a mole, or if it is instead a melanoma in its early stages of development. Because junctional nevi have a higher risk than other moles of developing into skin cancer, it is important to watch them for signs of melanoma. These signs include irregular pigmentation, asymmetry, irregular borders, or a size larger than .6 centimeters. To rule out melanoma, it is imperative to have a dermatologist check any mole that appears at all suspicious. If there is a doubt as to whether the mole is a melanoma or simply a junctional nevus undergoing a natural progression and becoming a compound nevus, it is generally a simple matter for the dermatologist to excise the mole for biopsy. Melanoma is an extremely dangerous type of skin cancer that often metastasizes to other areas of the body and can be fatal.
A junctional nevus itself is simply a young mole, and is not a reason for concern or sign of danger. However, if you are worried about the size, shape, or other appearance of your mole, be sure to see a dermatologist to set your mind at ease and rule out the possibility of skin cancer.