What are moles, freckles, skin tags, lentigines and seborrheic keratoses?

There are several skin lesions that are very common and almost always benign (non-cancerous). These conditions include moles, freckles, skin tags, benign lentigines, and seborrheic keratoses.

What is a mole?

Moles are growths on the skin that are usually brown or black. Moles can appear anywhere on the skin, alone or in groups.

Most moles appear in early childhood and during the first 20 years of a person's life. Some moles might not appear until later in life. It is normal to have between 10 to 40 moles by adulthood.

As the years pass, moles usually change slowly, becoming raised and lighter in color. Often, hairs develop on the mole. Some moles will not change at all, while others will slowly disappear over time.

What causes a mole?

Moles occur when cells in the skin grow in a cluster instead of being spread throughout the skin. These cells are called melanocytes, and they make the pigment that gives skin its natural color. Moles might darken after exposure to the sun, during the teen years, and during pregnancy.

What are the different types of moles?

Congenital nevi are moles that appear at birth. Congenital nevi occur in about one in 100 people. These moles might be more likely to develop into melanoma than are moles that appear after birth. If the mole is more than 8 inches in diameter, it poses more risk of becoming cancerous.

Dysplastic nevi are moles that are larger than average (larger than a pencil eraser) and irregular in shape. They tend to have uneven color with dark brown centers and lighter, uneven edges. These moles tend to be hereditary. People with dysplastic nevi might have more than 100 moles and have a greater chance of developing malignant (cancerous) melanoma. Any changes in the mole should be checked by a dermatologist to detect skin cancer.

What is a skin tag?

A skin tag is a small flap of tissue that hangs off the skin by a connecting stalk. Skin tags are benign and are not dangerous. They are usually found on the neck, chest, back, armpits, under the breasts, or in the groin area. Skin tags appear most often in women, especially with weight gain, and in middle-aged and elderly people.

Skin tags usually don’t cause any pain. However, they can become irritated if anything such as clothing or jewelry rubs on them.

What is a lentigo?

A lentigo (plural: lentigines) is a spot on the skin that is darker (usually brown) than the surrounding skin. Lentigines are more common among Caucasian patients, especially those with fair skin, but can occur in anyone.

What are freckles?

Freckles are small brown spots usually found on the face and arms. Freckles are extremely common and are not a health threat. They are more often seen in the summer, especially among lighter-skinned people and people with light or red hair. However, freckles can occur in anyone, and appear as darker brown spots in people with darker skin. Both men and women get freckles at an equal rate.

What are seborrheic keratoses?

Seborrheic keratoses are brown or black growths usually found on the chest and back, as well as on the head. They originate from cells called keratinocytes. As they develop, seborrheic keratoses take on a warty appearance.

What are the causes and what do I watch for in moles, freckles, skin tags, lentigines and seborrheic keratoses?

Most moles are benign. The only moles that are of medical concern are those that look different than other existing moles or those that first appear after age 20. If you notice changes in a mole's color, height, size, or shape, you should have a dermatologist (skin doctor) evaluate it. You also should have moles checked if they bleed, ooze, itch, appear scaly, or become tender or painful.

Examine your skin with a mirror or ask someone to help you. Pay special attention to areas of your skin that are often exposed to the sun, such as the hands, arms, chest, neck, face, and ears.

If your moles do not change over time, there is little reason for concern. If you see any signs of change in an existing mole, if you have a new mole, or if you want a mole to be removed for cosmetic reasons, talk to your dermatologist.

The following ABCDEs are important signs of moles that could be cancerous. If a mole displays any of the signs listed below, have it checked immediately by a dermatologist:

  • Asymmetry: One half of the mole does not match the other half.
  • Border: The border or edges of the mole are ragged, blurred, or irregular.
  • Color: The color of the mole is not the same throughout or has shades of tan, brown, black, blue, white, or red.
  • Diameter: The diameter of a mole is larger than the eraser of a pencil.
  • Elevation/Evolution: A mole appears elevated, or raised from the skin. Are the moles changing over time?

Melanoma is a form of skin cancer. The most common location for melanoma in men is the back; in women, it is the lower leg. Melanoma is the most common cancer in women ages 25 to 29.

What are the causes of lentigines?

Exposure to the sun seems to be the major cause of lentigines. Lentigines most often appear on parts of the body that get the most sun, including the face and hands. Some lentigines might be caused by genetics (family history) or by medical procedures such as radiation therapy.

What causes freckles?

Causes of freckles include genetics, diseases (such as xeroderma pigmentosum, a rare disease that causes an increased sensitivity to ultraviolet light, such as the sun), and exposure to the sun.

What causes seborrheic keratoses?

The cause of seborrheic keratoses is unknown. They are seen more often as people get older. They do not lead to skin cancer.

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