White Spots on the Skin: The Most Common Causes

Discolorations of the skin are very common. Some people develop red spots that are usually related to acne, while others develop dark spots that are often due to many years of sun exposure.

But what about the white spots we often develop on the hands (mainly on the forearms), the shins, or the face? Are they a natural consequence of age, or are they due to something else? And when should they lead us to the doctor?

“Depending on their appearance and the areas of the body where they develop, white spots can have various causes,” says Dr. Markos Michelakis, dermatologist-venereologist at EDOEAP. “In many cases they are signs of sun exposure, while in others they are indications of various skin conditions.”

It is estimated that every square centimeter of skin contains 7.6 million cells and 24,000 melanocytes. Melanocytes produce the skin’s pigment, melanin. The amount of melanin determines the skin’s tone. Overproduction darkens the skin, while lack of it makes it lighter than normal.

Sun exposure over a lifetime directly affects melanocytes, increasing or decreasing their number. When their number decreases, melanin production is reduced, and thus white spots may appear.

“The white spots caused by cumulative sun exposure are not painful or sensitive to the touch. They also do not cause itching,” explains Dr. Michelakis. “They are simply a change in skin coloration, which is often very bothersome.”

This change often appears as small drops (on average 1–3 millimeters in diameter) on the skin. Scientifically it is called idiopathic guttate hypomelanosis and it usually becomes more noticeable as a person tans from summer sun exposure. “Guttate hypomelanosis is not a cause for concern, but it requires extra protection from the sun because the areas with less melanin burn easily,” the specialist clarifies.

White spots on the skin, although larger than those of idiopathic hypomelanosis, can also be caused by pityriasis versicolor. This is a fungal skin infection that usually appears on the back or chest but can also affect the face.

In people with darker skin, its lesions appear lighter, while in those with lighter skin, they appear brownish. The condition is related to intense sweating, as fungi need moisture to grow.

The responsible fungi remove pigment from the skin, and its lack creates the characteristic spots, which do not have as clear borders as those of idiopathic hypomelanosis.

Pityriasis versicolor is treated with specific products and medications, but often it takes months — even a year or more — until skin pigmentation is restored. Sun exposure and increased sweating worsen the condition.

Another skin condition that causes white patches on the skin is vitiligo. This is a chronic autoimmune skin disorder in which the melanocytes of the skin are destroyed by the patient’s own immune system.

The skin lesions of vitiligo are not painful, but they are much larger than those of idiopathic hypomelanosis or pityriasis versicolor. Additionally, they are vulnerable to severe sunburns.

Vitiligo usually appears for the first time in young people (up to early adulthood). It may be associated with other autoimmune diseases, such as systemic lupus erythematosus. It typically begins with light-colored spots on the skin around the fingers, mouth, eyes, nose, navel, etc. It manifests as large, smooth “patches” of white or light skin that grow if left untreated.

Pityriasis alba also causes white spots on the skin. It is sometimes confused with a fungal infection, but in reality it is a form of atopic dermatitis (eczema). When the rest of the skin darkens due to sun exposure, the affected areas appear even whiter.

The white spots it causes usually appear in children and adolescents (mainly ages 3–16). They usually develop on the cheeks and generally the face, although they can also affect the neck, shoulders, and arms.

Their shape is round or oval and they are large (typically more than half a centimeter in diameter each). These spots are characterized by dryness, which sometimes causes itching. They may also peel, although this is more common in winter. At first they may be red as in eczema, but when they heal, white spots remain.

“Most white spots on the skin are not worrisome, but they often create an aesthetic problem that can be bothersome. However, they should be evaluated by a dermatologist in order to make the correct diagnosis and, if necessary, receive appropriate treatment,” emphasizes Dr. Michelakis. “This is especially important if the spots are spreading or growing. With timely intervention, skin pigmentation can be restored in many cases.”