Pityriasis alba and vitiligo are two skin diseases that present with skin depigmentation, sometimes making their distinction challenging. What are the specificities of each, and how can they be differentiated? Discover this by continuing your reading.
Pityriasis Alba or Vitiligo: How not to confuse these two conditions?
Summary
Published on November 26, 2024, by Pauline, Chemical Engineer — 6 min of reading
Themes:
Vitiligo and Pityriasis Alba: What are these conditions?
Vitiligo is an autoimmune skin disease, characterised by a selective loss of melanocytes, the cells responsible for skin pigmentation. This progressive destruction leads to the appearance of well-defined white patches, often symmetrical, on various parts of the body. Vitiligo is linked to genetic predisposition and triggering factors, such as oxidative stress, skin trauma, or immune imbalances. Furthermore, vitiligo is often associated with other autoimmune diseases, such as dysthyroidism or type 1 diabetes.
Pityriasis alba is a common and benign dermatological condition that primarily affects children and adolescents. Its etiology is currently unknown. This skin disease is often considered a minor manifestation of the atopic dermatitis and is generally associated with a history of atopy. Pityriasis alba presents as initially erythematous lesions that gradually become hypopigmented over time, hence the possible confusion with vitiligo.
The differences between pityriasis alba and vitiligo.
Even though vitiligo and pityriasis alba may appear similar, there are several factors that allow us to differentiate between them.
Vitiligo lesions and pityriasis alba do not quite have the same appearance.
As previously stated, the patches of pityriasis alba initially present as erythematous, unlike the white macules of vitiligo. Furthermore, it is not uncommon for pityriasis alba lesions to exhibit slight scaling, giving the skin a somewhat rough appearance. On the other hand, vitiligo spots are distinctly depigmented and the skin remains smooth and without scaling, increasing the contrast with the surrounding skin, especially in individuals with a dark phototype.
The areas of occurrence for vitiligo and pityriasis alba differ slightly.
Pityriasis alba frequently appears on areas exposed to the sun, such as the face, particularly the cheeks, and the arms. Vitiligo, on the other hand, can affect any part of the body. The white patches often appear symmetrically around the eyes or mouth, on the hands, feet or areas subject to repeated friction, such as the knees and elbows. The area of vitiligo occurrence, however, can vary considerably depending on its type.
The onset age of vitiligo and pityriasis alba varies.
Pityriasis alba most commonly appears in children and adolescents, typically before the age of 16. It can persist into adulthood but tends to fade over time, particularly due to the improvement of the skin barrier function, which is more fragile in children. Vitiligo, on the other hand, can occur at any age but often begins between 20 and 30 years old. Following certain trigger factors, it can manifest earlier, but is less common in children than pityriasis alba.
Vitiligo and pityriasis alba progress differently.
The progression of vitiligo is difficult to predict, as the condition can remain localised or gradually extend to other parts of the body, or even become generalised. Continuous management of the vitiligo is necessary to stabilise the lesions. Pityriasis alba, on the other hand, can disappear spontaneously, although the use of moisturising creams, sometimes accompanied by dermocorticoids, can accelerate its healing.
Pityriasis alba and vitiligo can be differentiated by a dermatologist.
Only a healthcare professional is capable of making an accurate diagnosis and distinguishing between vitiligo and pityriasis alba. The assessment is most often conducted using a Wood's lamp, a radiation device that emits long UVA and violet-blue light. When exposed to this light, the lesions of pityriasis alba may become more pronounced, but remain non-fluorescent. This differs from those of vitiligo, whose fluorescence is brighter and whose edges present a sharper demarcation.
| Criteria | Pityriasis Alba | Vitiligo |
|---|---|---|
| Appearance of Lesions | Initially slightly erythematous, occasionally accompanied by mild desquamation, rough skin. | Well-defined white spots, smooth skin without any peeling. |
| Location of Lesions | Areas exposed to the sun (face, cheeks, arms). | Various areas (hands, feet, face, knees, elbows, sometimes symmetrical). |
| Age of Onset | Common among children and adolescents under the age of 16. | Can occur at any age, but often begins between 20 and 30 years old. |
| Progression of Lesions | Often disappears spontaneously over time. | Can progress, becoming generalised or localised and requires ongoing management. |
| Differential Diagnosis | Wood's Lamp: Non-fluorescent lesions. | Wood's Lamp: bright fluorescence, clear and white spots. |
Tableau récapitulatif des critères d'identification du vitiligo et du pityriasis alba.
Sources
GIVLER D. & al. Pityriasis Alba. StatPearls (2024).
RUDNICKA L. & al. Pityriasis Alba—Common Disease, Enigmatic Entity: Up-to-Date Review of the Literature. Pediatric Dermatology (2015).
BORRADORI L. & al. Dermatologie et infections sexuellement transmissibles. Elsevier Masson (2017).
EZZEDINE K. & al. Vitiligo: A Review. Dermatology (2020).
HARRIS J. & al. Vitiligo: Mechanisms of Pathogenesis and Treatment. Annual Review of Immunology (2020).
