Moles come in all variety of shapes and sizes. It can be difficult at times to be certain what you are looking at if you aren’t familiar with the different types of pigmented lesions a body can acquire. Here are some basics worth considering when you give your body the once, or twice, over.

A good way to define the differences in pigmented lesions is to first explain what freckles are. Best described as numerous brown spots which group together in numbers too high to count, freckles appear from sun exposure and don’t turn into melanoma.

Lentigos are another common lesion, occurring in the elderly and looking like large brown spots. Other common names for them are old age spots or liver spots. They are similar to freckles, are completely flat and have a light brown or tan color. Occurring in isolation rather than clumps like freckles, they are easier to identify.

Nevus is the medical name given to moles, with nevi being the plural form of the word. What nevi are is a cluster of melanocytes that appear as brown spots on the skin. They can be any shade of brown and are called melanocytes for the existence of melanin which gives them their color. The cells which make up a nevus are called nevus cells, as you might expect.

Many people have moles all over their body and often they are different kinds of moles. The two categories of moles are common acquired nevi and congenital nevi. The first are the most common type of pigmented lesions and are those which occur sometime throughout a person’s life. The numbers of these nevi increase as a person ages. Rarely do you find young children with numerous moles, but the person over 30 may have many.

Common acquired nevi are classified as junctional, intradermal or compound nevi. These names originated with the location of the clusters of melanocytes present. What this means is that junctional nevi are found at the skin’s dermal-epidermal junction, which is the top and second layer of the skin. In the compound nevi, the cells are found in both layers of the skin. For the intradermal nevi, the cells are found in the dermis only.

To recognize these moles, here are some guidelines. Junctional nevi, or moles, are flat since they have few cells in their structure. They are darkest shades of brown and some of the most likely moles to become malignant melanoma. Compound nevi are lighter shades of brown and tend to be a bit raised up off the skin. These nevi might also have both a raised and flat component to them. Intradermal nevi are elevated and look like a dome shape and may even be the same color as the skin and difficult to distinguish from surrounding areas.

Common acquired moles can develop for different reasons. The most widely held belief relates to sun exposure and there is some scientific data to support this belief. People who live in sunny or tropical climates have a higher incidence of melanoma than colder, cloudier places in the world.

Congenital nevi are also known as birthmarks and occur in one out of every 100 people in all races of human beings. Sometimes more than one might be present at birth, though this isn’t the norm. These moles will last a lifetime unlike common acquired moles which usually fade away with age. These moles can be very large or smaller in size. Their color ranges from tan to a brown color or even black. Most often, there is also a hair raised out of the middle of the mole. These moles can also become melanoma just like common acquired moles and need to be monitored for any changes.

Giant congenital nevi also occur and tend to cover a large amount of area on a person’s body. These are rather rare though and occur in approximately one out of every 100,00 births. They can be small or large; dark brown or bluish-black and have a raised rough pebble-like surface. The risk of these moles becoming melanoma is 5 to 10 percent in a lifetime. Removing them can be very difficult since they often penetrate more than one layer of skin and make disfigurement more of a risk.

One comforting aspect of all of this, is that the majority of moles will never become melanoma. The average person has 30 to 35 nevi and that lifetime risk of developing melanoma calculates into one in 100 chance. The key in all of this explanation is to watch the moles and notice any changes. Whether it is a common acquired mole or a congenital mole, anything that looks different about it compared to the past, should be checked out with your physician to be certain it has not developed into the life-threatening skin cancer, melanoma.