Why do we develop more moles as we age?

Also known as nevi, moles are dark-colored spots that appear on the skin in rounded or oval shapes. They can be flat or raised and are completely painless and benign. However, they need to be monitored to ensure they do not transform into melanoma, a dangerous form of skin cancer. The moles form due to an accumulation of melanocytes in the epidermis. As a reminder, melanocytes are the cells that produce melanin, the pigment that colors the skin. Nevi typically appear on areas frequently exposed to the sun, such as the face, arms, and legs. The size, color, and number of moles vary among individuals.

The number of moles on the skin can be considered an indicator of bodily aging.

It is uncommon to be born with moles. In this unique circumstance, we refer to it as a congenital nevus. Most moles develop during childhood and adolescence, primarily in response to exposure to the sun's UV rays. This is due to the fact that the skin of young children is naturally more sensitive and reactive to environmental stimuli, such as UV rays. These rays encourage the proliferation of melanocytes and their clustering in the epidermis, leading to the formation of moles.

Besides sun exposure, hormonal fluctuations also contribute to the emergence of nevi. Adolescence is a period marked by hormonal upheavals, particularly an increase in certain hormone levels, such as androgens, which influence the proliferation of skin cells. These hormonal changes can stimulate the appearance of new moles or cause changes in existing ones. Similarly, pregnancy is a period conducive to the appearance of moles. Under the effect of hormonal fluctuations, particularly the increase in estrogen and progesterone, melanocytes become more active, which increases the likelihood of moles appearing. This phenomenon is similar to the hyperpigmentation sometimes observed on the bodies of pregnant women, referred to as pregnancy mask.

It is uncommon for new moles to appear in adulthood. Most nevi tend to stabilize after the age of 30. If you notice the emergence of new moles after this age, it is advisable to consult a dermatologist to ensure that it is not a melanoma.

As we age, it's common to notice the emergence of new spots on the skin, often perceived as moles. However, what many people consider as new moles are actually seborrheic keratoses, benign growths that frequently appear from the age of forty. They are often raised and seem to be placed on the skin, somewhat like a crust. Their average size is 0.5 to 1 cm, but they can sometimes be larger. Seborrheic keratoses are painless, even though they can sometimes cause discomfort if they are located in areas of friction or likely to be snagged by clothing or jewelry.

Despite their sometimes unsightly appearance, seborrheic keratoses are benign lesions that do not progress into skin cancer, unlike certain moles. The mechanism of their development is still under study, but it appears that extrinsic skin aging, particularly due to prolonged sun exposure, is a major factor. As skin ages, mutations occur in certain signaling molecules, notably those of the fibroblast growth factor receptor 3, which is involved in the regulation of cell growth. These mutations are frequently found in seborrheic keratoses. However, these changes are not associated with a malignant potential.

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