Benign Lesions (Lesions That Are Not Cancerous)
These appear during childhood or adulthood. There are 3 types of acquired nevi:
Junctional Melanocytic Nevi
- They tend to first appear in childhood as flat, freckle-like lesions of brown, dark brown, or black, and are uniform in color.
These moles are called "junctional nevi" because the melanocytes that make them are located at the junction of the epidermis and dermis.
They are most commonly found on the face, arms, legs, trunk, genitals, or soles of the feet.
During adulthood, these nevi may become more raised, lose pigmentation, or even disappear.
- These are flesh-colored or light brown, dome-shaped lesions that are only on the dermis.
The other name for these moles are "dermal nevi".
The melanocytes that make up an intradermal nevus are located in the dermis (below the dermo-epidermal junction). This mass of melanocytes pushes the cells above it upward, resulting in the flesh-colored bump that is noted on the surface of the skin.
They are most commonly found in adults.
Nonpigmented dermal nevi are also called cellular nevi.
- These have features of both junctional and intradermal nevi.
- The melanocytes are located both in the dermo-epidermal junction and the dermis. They are usually raised and have uniform pigmentation.
Other Benign Lesions
- Small, tan, flat spots that appear in response to the sun's ultraviolet radiation.
- The medical name for a freckle is an "ephelide".
- Freckles darken with sun exposure and lighten or fade when no longer exposed.
- They tend to cluster together in large numbers.
Lentigines (singular, lentigo)
- Also known as sunspots, age spots, or liver spots, although they have nothing to do with the liver or liver function. Lentigines are flat, brown, sometimes large spots that are associated with sun-damaged skin.
Unlike freckles, they are usually discrete spots that do not fade when no longer exposed to the sun.
Lentigines are very common in people over 40.
You'll find them in areas of greatest sun exposure: on the face, arms, chest, shoulders, back, and backs of the hands.
IMPORTANT! Because lentigines are a marker for sun damage, people with lentigines are at increased risk for developing melanoma.
Raised, benign growths of keratinocytes in the upper layers of the skin (the epidermis). These keratinocytes are often pigmented, which gives the seborrheic keratosis its dark, mole-like appearance.
They are sometimes mistaken for warts or melanoma and range in color from tan to dark brown or black. They have a waxy, pasted-on appearance which is why they are sometimes described as "brown candle wax on the skin."
Seborrheic keratoses can appear on sun-exposed or covered areas. They never grow on the palms or soles or in the mouth or eyes.
Unlike moles, seborrheic keratoses are usually rough to the touch.
Seborrheic keratoses are the most common benign lesions that mimic the appearance of melanoma. Although a seborrheic keratosis cannot turn into a melanoma because it is not made of melanocytes, it cannot be completely ignored because a melanoma can occur next to them and may be mistaken for an extension of the seborrheic keratosis.
People with fair skin who freckle or burn easily are at increased risk of developing melanoma.
- Clusters of melanocytes often form pigmented spots on the skin.
- These groups of melanocytes are called melanocytic nevi, or moles.
- Freckles are caused by a normal number of melanocytes that make an abnormal amount of pigment.
- Unlike moles, freckles tend to grow darker when there is a lot of sun exposure and lighter when kept out of the sun.