Pityriasis Alba: Causes, Symptoms, Diagnosis and Treatment

What is Pityriasis Alba?

The name pityriasis alba contains two important descriptive clues:

• “Pityriasis”, derived from the Greek pityron (meaning bran), refers to a skin condition characterized by fine, bran-like scaling (desquamation).
• “Alba” (from Latin for “white”) highlights the characteristic pale color of the skin lesions.

Together, pityriasis alba describes a benign form of cutaneous hypomelanosis, a condition in which patches of skin show reduced or absent pigmentation with subtle, fine-scale desquamation. These patches arise as the post-inflammatory aftermath of prior skin inflammation, most commonly atopic dermatitis (eczema).

Who Is Most Affected?

• Children are predominantly affected, particularly those with a background of atopic dermatitis (eczema). In these cases, maintaining good skin hydration with emollients is essential for both managing atopic dermatitis and preventing the development of pityriasis alba.
• The condition affects both sexes equally
• It is worldwide in distribution, but is more visible and therefore more commonly reported in individuals with darker skin tones because the contrast between the hypopigmented patches and the surrounding skin is greater.

Is It Serious?

Pityriasis alba is a benign and self-limiting condition. The prognosis is excellent:

• Lesions tend to regress spontaneously over time, typically as the child grows older
• There are no complications
• It is not contagious, meaning it cannot be transmitted from person to person

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Cause

Pityriasis alba is a post-inflammatory hypopigmentation. The pale patches represent the skin’s healing response after inflammation, not a primary pigment disorder.

Mechanism

During an inflammatory skin process, even a mild one, the activity of local melanocytes is temporarily disrupted. These cells are responsible for producing melanin, the pigment that darkens the skin. As the inflammation resolves, the affected skin heals with reduced melanin content, resulting in the characteristically pale appearance of the patches.

Primary Underlying Cause

The most common preceding inflammatory condition is atopic dermatitis (eczema), a chronic and relapsing inflammatory skin disease that predominantly affects children. This explains why pityriasis alba is most common in the pediatric age group.

Contributing Factors

In addition to atopic dermatitis, the following can trigger or worsen the condition:

• Frequent washing with hot water or harsh soaps disrupts the skin barrier and promotes inflammation.
• Aggressive or irritating detergents strip the skin’s natural protective lipid layer.
• Sun exposure: While sunlight darkens surrounding normal skin, the hypopigmented patches do not tan. This makes them appear more noticeable in summer.
• Dry environmental conditions can worsen skin dryness and disrupt the skin barrier.

Key reassurance: Pityriasis alba is not an infection, not an allergy, and not contagious. It cannot spread to other people.

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Symptoms

Pityriasis alba presents with a characteristic and recognizable clinical appearance:

Appearance of the Patches

• Color: White to pale pink. This shade is only slightly lighter than the surrounding skin. In darker skin tones, the contrast is more pronounced.
• Borders: Poorly defined, indistinct, and gradually blending into the surrounding normal skin (unlike vitiligo, where the borders are typically sharp and well-defined)
• Surface: Fine, barely perceptible, superficial scaling (pityriasiform desquamation)
• Texture: The skin surface may feel slightly rough or dry compared to adjacent normal skin

Size and Number

• Individual lesion diameter: 5 to 30 mm
• Number of lesions: Ranges from very few (2–3 patches) to numerous (up to 20 patches)

Anatomical Distribution

The face is the most commonly affected area, particularly:

• Cheeks (the most frequent site)
• Forehead
• Periocular region (around the eyes)
• Perioral region (around the mouth)

Less commonly, lesions may also appear on:

• Neck
• Trunk
• Back
• Scrotum (in males)
• Limbs (arms and legs)

Associated Symptoms

In the vast majority of cases, there are no significant symptoms. The condition is primarily a cosmetic concern. A minority of patients may experience:

• Mild pruritus (itching), particularly during inflammatory phases.

Natural Course

Pityriasis alba is a self-limiting condition. The patches tend to spontaneously and progressively fade as the child ages, typically resolving completely by adulthood. Complete resolution may take months to years, but permanent residual hypopigmentation is not expected.

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Diagnosis

Clinical Diagnosis

The diagnosis of pityriasis alba is primarily clinical, as it relies on the characteristic appearance and distribution of the lesions observed during physical examination. In most cases, no additional testing is required.

The physician will assess:

• The morphology, color, borders, and distribution of the patches
• The presence of associated atopic features (personal or family history of eczema, asthma, allergic rhinitis)
• Skin dryness and overall skin barrier function

Differential Diagnosis: Distinguishing Pityriasis Alba from Similar Conditions

Two conditions in particular must be distinguished from pityriasis alba:

1. Tinea Versicolor (Pityriasis Versicolor)

Tinea versicolor is a fungal infection (Malassezia species) that also causes hypopigmented patches with fine scaling. These patches can closely resemble pityriasis alba.

Distinguishing test: Mycological examination (fungal scraping)

• Scale material is collected from a lesion by gently scraping with a surgical instrument called a curette.
• The sample is examined under a microscope (direct microscopic examination) to identify fungal elements, such as hyphae and spores. In tinea versicolor, these often display the classic “spaghetti and meatballs” appearance.
• The sample is also cultured on fungal growth media to confirm or exclude fungal colonization.

Clinical distinguishing features:

• Tinea versicolor is more common in adolescents and adults (not typically young children)
• Lesions are typically on the trunk, shoulders, and upper arms (rather than predominantly the face)
• Lesions may appear hyperpigmented (darker than surrounding skin) in lighter-skinned individuals

2. Vitiligo (Vitiligine)

Vitiligo is an autoimmune depigmentation disorder in which melanocytes are destroyed. This process produces completely white patches, indicating a total loss of pigmentation rather than just reduced pigmentation.

Distinguishing test: Wood’s lamp examination

• Under Wood’s lamp (a UV light source emitting long-wave ultraviolet radiation at approximately 365 nm):
  • In vitiligo: Lesions appear brilliantly white (bright fluorescence) due to complete loss of melanin; borders are sharp and well-defined
  • In pityriasis alba: Lesions appear only slightly lighter under Wood’s lamp; no fluorescence; borders remain indistinct

Clinical distinguishing features:

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Treatment

Is Treatment Always Necessary?

Because pityriasis alba is self-limiting and benign, treatment is not always strictly necessary. The patches will eventually fade on their own.

However, treatment is appropriate when:

• The cosmetic appearance may cause distress or concern, particularly in adolescents who have visible facial lesions.
• The underlying atopic skin is dry or symptomatic (itching, roughness).
• The lesions are extensive.

First-Line Treatment: Skin Hydration

Regular and consistent application of emollient creams or lotions is the cornerstone of management:

• Fragrance-free, hypoallergenic emollients should be applied generously to the affected areas, and ideally to all dry skin, at least once or twice daily.
• Emollients restore the skin barrier, reduce dryness and scaling, and help prevent further episodes of inflammation that lead to post-inflammatory hypopigmentation
• This is particularly important in children with underlying atopic dermatitis, where daily emollient use is a fundamental part of long-term skin management

Topical Corticosteroids

Low-potency topical corticosteroid creams (e.g., hydrocortisone 1%) can be helpful in active or itchy phases:

• They reduce any residual inflammation within the lesions
• They should be used for short-term courses only, and only under medical guidance. They should not be taken indefinitely.
• Higher-potency corticosteroids are generally not indicated for this condition, particularly on the face

Sun Protection

• Broad-spectrum sunscreen should be applied daily to sun-exposed areas
• While sun exposure can darken surrounding skin and make patches appear more noticeable, physical sun protection helps prevent exacerbation of the contrast
• A note: the patches themselves will not tan normally. It is important to counsel patients to avoid deliberate sun-seeking to even out the color, as this strategy is counterproductive.

Phototherapy

For extensive or persistent cases unresponsive to topical measures, published evidence supports the use of:

• Narrowband UVB phototherapy: Exposure to specific ultraviolet wavelengths within controlled medical cabins can stimulate melanocyte activity and help repigment the affected areas
• This is delivered in a specialized clinical or hospital setting and requires multiple sessions
• It is generally reserved for more severe or extensive cases, given the availability, cost, and radiation exposure involved

Avoiding Triggering Factors

Practical measures to reduce recurrence:

• Use gentle, soap-free cleansers. Avoid harsh soaps, scrubbing, and frequent bathing with hot water.
• Maintain room humidity, especially in dry climates or during winter months, since central heating dries the air.
• Treat underlying atopic dermatitis appropriately. Controlling the eczema reduces the risk of further post-inflammatory hypopigmentation episodes.

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Sources and Bibliography

• Braun-Falco O., Plewing G., Wolff H.H., Burgdorf W.H.C. Dermatologia. Italian edition edited by Carlo Gelmetti. Springer–Verlag Italia, 2002.
• Saurat J, Grosshans E., Laugier P, Lachapelle J. Dermatologia e malattie sessualmente trasmesse. Italian edition edited by Girolomoni G. and Giannetti A. Third edition, 2006. Masson.
• Ortonne J., Bahadoran P., Fitzpatrick T., Mosher D., Hori Y. Hypomelanosis and Hypermelanosis. Chapter 90. In: Fitzpatrick’s Dermatology in General Medicine, edited by Eisen A, Wolff K, Austen K, Goldsmith L, Katz S, Freedberg I. McGraw Hill, 2003.
• PMC: Pityriasis Alba: A Comprehensive Review
• Jadotte YT, Schwartz RA. “Pityriasis alba revisited: perspectives on an enigmatic disorder of childhood”. Cutis. 2010;85(3):137–144.
• DermNet NZ: Pityriasis Alba
• American Academy of Dermatology: Pityriasis Alba