White spots on the skin: the most common causes

First: is a white patch truly 'without pigment'?

Not necessarily.

In dermatology, we distinguish between two concepts that may seem similar.

Hypopigmentation: the skin retains pigment, but contains less melanin than the surrounding skin. The area appears lighter.

Depigmentation: there is a much more complete loss of pigment. The lesion may appear clearly white.

This difference can provide important information for diagnosis. There are numerous conditions capable of producing hypopigmentation or depigmentation, and their appearance alone does not always allow us to tell them apart.

What are the most common causes?

Let's look at some of those we encounter most frequently.

1. Pityriasis versicolor

Pityriasis versicolor is a common cause of lighter patches, especially in young people and in warm, humid climates.

It is related to the proliferation of yeasts of the genus Malassezia, microorganisms that normally form part of our skin microbiome.

Lesions frequently appear on: the chest, back, shoulders, neck, and upper arms.

They may be lighter, darker, or even slightly pinkish. And they usually present with very fine scaling.

Why are they more noticeable after summer?

Because the healthy skin surrounding the lesions tans.

The affected areas may not pigment in the same way.

Then a much greater contrast appears.

That is why some patients discover pityriasis versicolor after sun exposure. Not necessarily because it appeared at that moment. It is simply much more visible now.

Is it contagious?

Although a yeast is involved, pityriasis versicolor is not considered a contagious infection in the usual sense.

Malassezia is normally part of our skin's microbiota.

The problem arises when it proliferates in a way that favors the development of lesions.

Does the color return immediately after treatment?

Not always. This point is very important.

We can eliminate the proliferation of Malassezia and yet the skin may remain lighter for weeks or even months.

That does not necessarily mean that the treatment has failed.

Eliminating the cause and recovering the pigment are two different processes.

2. Pityriasis alba

Another very common cause, especially in children and adolescents, is pityriasis alba.

It usually appears as slightly lighter patches, frequently on: the cheeks, chin, neck, shoulders, or arms.

The borders are usually poorly defined and fine scaling may be present.

It is considered a mild form of dermatitis and appears more frequently in people with dry skin or an atopic tendency.

Why is it more noticeable in summer?

The contrast effect appears again.

Normal skin tans. The hypopigmented area does so less.

That is why the lesions appear much whiter after sun exposure.

This is especially relevant when parents come in concerned about white spots on a child's face.

It does not automatically mean vitiligo. Pityriasis alba is a common possibility in this context.

3. Post-inflammatory hypopigmentation

Our skin can change color after inflammation.

We are used to thinking about the dark marks left by acne. But the opposite can also happen.

After dermatitis, a skin lesion, a burn, or certain procedures, the area may temporarily become lighter.

This is called post-inflammatory hypopigmentation.

The clue often lies in the clinical history.

When we ask: 'What was here before the white spot appeared?' the patient recalls: 'I had dermatitis.' 'I got a burn.' 'I had a lesion.' 'I had a procedure done.'

Then we begin to understand what has happened.

In many cases the pigment can gradually return once the inflammation resolves, although it may take weeks or months.

4. Vitiligo

And yes: white spots on the skin can also correspond to vitiligo.

Vitiligo is a disease in which functional melanocytes are lost, and as a result, depigmented areas appear.

The lesions are usually clearly white and can appear on different parts of the body.

But there is something we must remember: seeing a white spot does not automatically allow a diagnosis of vitiligo.

The American Academy of Dermatology itself insists that light or white areas can be due to vitiligo, pityriasis versicolor, skin lesions, and other causes, which is why a correct diagnosis is important.

We will have a complete article dedicated to vitiligo, because it deserves a specific explanation.

5. Idiopathic guttate hypomelanosis

There is another type of white spot that is extremely common and that many people begin to notice over the years.

They are small white spots, generally just a few millimeters in size.

They appear especially in sun-exposed areas, such as: forearms, arms, and legs.

It is called idiopathic guttate hypomelanosis.

It is a benign pigmentation disorder that is particularly associated with age and cumulative sun exposure.

It is not vitiligo. It is not an infection. And it is not cancer.

It is one of the causes we must consider when multiple small white spots appear in sun-exposed areas.

So, how do we know what type of white spot we have?

By looking at several characteristics.

Is it completely white or simply lighter? Does it have scaling? Does it itch? Where is it located? Is it a single spot or are there multiple ones? Is it growing? Was there a prior dermatitis? Did it appear after an injury or procedure? Is there a personal or family history of vitiligo?

Each answer modifies our diagnostic possibilities.

Location also helps us

A pityriasis versicolor affecting mainly the trunk does not behave the same way as vitiligo around the eyes or mouth.

Pityriasis alba on the cheeks of a child has a different context.

And multiple small white spots on the forearms and legs of a sun-exposed adult point us toward other possibilities.

In dermatology, the distribution of lesions is part of the diagnosis.

What is a Wood's lamp?

In certain situations we can use a tool called a Wood's lamp.

It emits long-wave ultraviolet radiation and helps us observe certain pigmentary alterations in a way that cannot be appreciated equally under normal light.

It can be particularly useful for evaluating a suspected case of vitiligo and for differentiating certain pigmentation disorders.

In other cases we may need dermatoscopy, skin scraping to study fungi, or other examinations depending on the diagnostic suspicion.

Are white spots caused by fungi?

Some may be related to a yeast, as occurs in pityriasis versicolor.

But many others are not.

That is why we must also avoid making the opposite mistake: 'I have white spots, I'm going to use an antifungal.'

If we have vitiligo, pityriasis alba, or post-inflammatory hypopigmentation, an antifungal will not solve the problem.

Once again: treatment depends on the diagnosis.

Does sun exposure help restore color?

We should not use unprotected sun exposure as a home remedy.

In many conditions, tanning of the surrounding normal skin simply increases the contrast and makes the white patch look even more noticeable.

In addition, unnecessarily increasing ultraviolet exposure means increasing accumulated sun damage.

When we use ultraviolet light as a medical treatment for certain conditions, such as some forms of vitiligo, we are talking about controlled medical phototherapy, with specific wavelengths, doses, and protocols.

That is completely different from sunbathing.

Is there a cream to restore pigment?

There is no universal cream for all white patches.

And now we can understand why.

If we have pityriasis versicolor, we treat the proliferation of Malassezia.

If we have pityriasis alba, we may primarily need moisturization and control of the dermatitis.

If there is post-inflammatory hypopigmentation, we must address the underlying cause and allow for gradual recovery.

And if we have vitiligo, we have entirely different treatments available.

Same color. Different conditions. Different treatments.

When should we seek medical advice?

It is worth having a white patch evaluated when: it appears without a clear cause, it grows progressively, new lesions appear, it is completely white, it affects several areas of the body, it appears around the eyes, mouth, hands or genitals, there is loss of pigmentation in the hair within the affected area, there is persistent scaling, or we simply do not know what is happening.

Especially when lesions are progressing, establishing the correct diagnosis allows us to decide whether treatment is needed.

What I want you to remember

If you search the Internet for a disease causing white patches on the skin, you will probably come across the word vitiligo very quickly.

But I want you to remember one thing: white is not a diagnosis.

A white patch may be pityriasis versicolor. Pityriasis alba. Post-inflammatory hypopigmentation. Idiopathic guttate hypomelanosis. Vitiligo. Or one of several other, far less common causes.

That is why we do not simply treat the colour we see.

We look at the distribution. The texture. The scaling. The progression. The history of the skin.

And when necessary, we use tools such as the Wood's lamp, dermatoscopy or mycological testing.

Because before attempting to restore pigment, we need to answer one question: why was it lost?

And only then can we choose the right treatment.