eMedicine Specialties > Pediatrics: General Medicine > Dermatology
Pityriasis Alba
Updated: Oct 8, 2009
Introduction
Background
Pityriasis alba (PA) is a relatively common skin disorder in children and young adults. It is characterized by the presence of ill-defined, scaly, faintly erythematous patches that subside to leave areas of hypopigmentation. Lesions may progress through the following 3 clinical stages:
- Papular (scaling) erythematous
- Papular (scaling) hypochromic
- Smooth hypochromic
Lesions eventually subside, leaving areas of hypopigmentation that slowly repigment to normal. The duration of pityriasis alba varies from one month to 10 years, but most cases resolve over several months to one year. Diagnosis is made clinically, and treatment consists of skin care and education of the parents about the benign nature of the disorder. Hydrocortisone may decrease erythema, scale, and pruritus, if present. Pityriasis alba is a nonspecific finding that is commonly associated with atopic dermatitis. Xerosis that presents in individuals with atopic diathesis is an important element in the development of the disease. The etiology is unknown.
Note the characteristic, ill-defined, hypopigmented macules in this 6-year-old child with pityriasis alba.
Lesions of pityriasis alba are usually bilateral and located on the face, arms, and neck.
The hypopigmentation produced by pityriasis alba may take a year or longer to return to normal.
This older patient with areas of hypopigmentation on the face has a common problem that would be included in the differential diagnosis of pityriasis alba. Several months earlier, he had areas of irritant contact dermatitis on his cheeks. When those resolved, he was left with areas of postinflammatory hypopigmentation. These should eventually repigment to an even skin tone.
Pathophysiology
In a study of 9 patients with extensive pityriasis alba, the density of functional melanocytes was reduced in the affected areas without any change in cytoplasmic activity.1 The melanosomes tended to be fewer and smaller, but their distribution pattern in the keratinocytes was normal. Melanosomal transfer to keratinocytes was generally not disturbed. Histology was nonspecific. Hyperkeratosis and parakeratosis were not consistently present, and they are seemingly unlikely to play a significant role in the pathogenesis of the hypomelanosis. A variable degree of intercellular edema and intracytoplasmic lipid droplets were present. Hypopigmentation may be primarily due to the reduced numbers of active melanocytes and a decrease in number and size of melanosomes in the affected skin.
Frequency
United States
Although the exact incidence has not been described, up to one third of school-aged children may have this disorder. Pityriasis alba is not seasonal, but the dry, slightly scaling appearance tends to worsen during cold months, when the air is relatively dry inside the home. In addition, sun exposure may make the lesions more obvious during spring and summer. The condition is more common in patients with a history of atopy.
International
In a large study of 9955 schoolchildren aged 6-16 years who lived in a tropical region, the prevalence of pityriasis alba was 9.9%.2
Mortality/Morbidity
Pityriasis alba is generally self-limited and asymptomatic. Cosmetic appearance may be an issue in some patients. Daycare facilities and schools may voice concern about the disorder and request the child be evaluated to rule out an infectious disease.
Race
Pityriasis alba occurs in people of all races. One study found the incidence to be slightly higher in light-skinned people. The condition is frequently more apparent and cosmetically bothersome in patients with darker complexions.
Sex
Pityriasis alba is more prevalent in males than in females.
Age
Pityriasis alba is most common in children aged 3-16 years. Ninety percent of cases occur in children younger than 12 years. Pityriasis alba occasionally occurs in adults.
Clinical
History
- Pityriasis alba (PA) is generally asymptomatic but may be mildly pruritic.
- Patients may describe any of the following 3 clinical stages:
- Papular erythematous lesions
- Papular hypochromic lesions
- Smooth hypochromic lesions
- Initially, erythema may be conspicuous, and minimal serous crusting of some lesions may occur; however, because the erythema is usually very mild, most parents do not recall the erythematous stage.
- Recurrent crops of new lesions may develop at intervals.
- The duration of pityriasis alba varies from one month to 10 years. The average duration of the common facial form in childhood is one year or more.
- Important aspects of patient history include the following:
- Patient or family history may include asthma, hay fever, or eczema in the characteristic areas of atopic dermatitis. Pityriasis alba is a nonspecific finding that is commonly associated with atopic dermatitis.
- The patient may have prior history of rash or eczema at the sites of hypopigmentation; skin irritation produced by any of various causes may heal with postinflammatory hypopigmentation.
- Ask about prior therapy; potent topical steroids may produce hypopigmentation. Patients may develop irritant or allergic contact dermatitis to various topical creams, lotions, and medications. When these are discontinued and the area recovers from the contact dermatitis, an area of postinflammatory hypopigmentation may occur.
- Look for seasonal variations in appearance; the scaling areas of hypopigmentation frequently develop during winter but become more apparent following sun exposure during the spring and summer.
Physical
- Characteristic lesions
- Pityriasis alba is characterized by hypopigmented, round-to-oval, scaling patches on the face, upper arms, neck, or shoulders. The legs and trunk are less commonly involved.
- Lesions vary in size, usually 1-4 cm in diameter.
- Most commonly, patients have multiple lesions that range in number from 4-5 to 20 or more.
- Scales are fine and adherent.
- Affected areas
- In approximately one half of all patients, the lesions are limited to the face. In children, the lesions are often confined to the face. The areas around the mouth, chin, and cheeks are the most commonly affected.
- In 20% of affected children, the neck, arms, and shoulders are involved in addition to the face.
- Less commonly, the face is spared and scattered lesions are present on the trunk and limbs.
- Rarely, the disease may be quite extensive. Patients with extensive pityriasis alba present with numerous lesions on the trunk and extremities. This form of pityriasis alba generally occurs in older patients, and the lesions may be more persistent.
- Important aspects of examination
- Examine patients for keratotic lesions on the elbows and knees and for small pits in the nails, which may suggest a diagnosis of psoriasis.
- Examine for the following potential signs of atopic dermatitis:
- Eczema in the popliteal or antecubital fossa
- Nipple eczema
- Cheilitis
- Dennie-Morgan infraorbital fold
- Anterior neck folds
- Wool intolerance
- White dermographism
- Infra-auricular fissuring
Causes
- No definitive etiologic agent has been described.
- Excessively dry skin, which is frequently exacerbated by cold dry environments, appears to be a common factor.
- Lesions are visible primarily in contrast to dark skin. Increasing sunlight in spring and summer makes them more apparent.
- The condition is not contagious, and no infectious agent has been identified.
More on Pityriasis Alba |
 Overview: Pityriasis Alba |
| Differential Diagnoses & Workup: Pityriasis Alba |
| Treatment & Medication: Pityriasis Alba |
| Follow-up: Pityriasis Alba |
| Multimedia: Pityriasis Alba |
| References |
| Next Page » |
References
Zaynoun ST, Aftimos BG, Tenekjian KK, et al. Extensive pityriasis alba: a histological histochemical and ultrastructural study. Br J Dermatol. Jan 1983;108(1):83-90. [Medline].
Bechelli LM, Haddad N, Pimenta WP, et al. Epidemiological survey of skin diseases in schoolchildren living in the Purus Valley (Acre State, Amazonia, Brazil). Dermatologica. 1981;163(1):78-93. [Medline].
In SI, Yi SW, Kang HY, Lee ES, Sohn S, Kim YC. Clinical and histopathological characteristics of pityriasis alba. Clin Exp Dermatol. Jul 2009;34(5):591-7. [Medline].
Vargas-Ocampo F. Pityriasis alba: a histologic study. Int J Dermatol. Dec 1993;32(12):870-3. [Medline].
Martin RF, Lugo-Somolinos A, Sanchez JL. Clinicopathologic study on pityriasis alba. Bol Asoc Med P R. Oct 1990;82(10):463-5. [Medline].
Jorizzo J, Levy M, Lucky A, et al. Multicenter trial for long-term safety and efficacy comparison of 0.05% desonide and 1% hydrocortisone ointments in the treatment of atopic dermatitis in pediatric patients. J Am Acad Dermatol. Jul 1995;33(1):74-7. [Medline].
Queille C, Pommarede R, Saurat JH. Efficacy versus systemic effects of six topical steroids in the treatment of atopic dermatitis of childhood. Pediatr Dermatol. Jan 1984;1(3):246-53. [Medline].
Rigopoulos D, Gregoriou S, Charissi C, Kontochristopoulos G, Kalogeromitros D, Georgala S. Tacrolimus ointment 0.1% in pityriasis alba: an open-label, randomized, placebo-controlled study. Br J Dermatol. Jul 2006;155(1):152-5. [Medline].
Fujita WH, McCormick CL, Parneix-Spake A. An exploratory study to evaluate the efficacy of pimecrolimus cream 1% for the treatment of pityriasis alba. Int J Dermatol. Jul 2007;46(7):700-5. [Medline].
Blessmann Weber M, Sponchiado de Avila LG, Albaneze R, et al. Pityriasis alba: a study of pathogenic factors. J Eur Acad Dermatol Venereol. Sep 2002;16(5):463-8. [Medline].
Di Lernia V, Ricci C. Progressive and extensive hypomelanosis and extensive pityriasis alba: same disease, different names?. J Eur Acad Dermatol Venereol. May 2005;19(3):370-2. [Medline].
du Toit MJ, Jordaan HF. Pigmenting pityriasis alba. Pediatr Dermatol. Mar 1993;10(1):1-5. [Medline].
Fink-Puches R, Chott A, Ardigo M, et al. The spectrum of cutaneous lymphomas in patients less than 20 years of age. Pediatr Dermatol. Sep-Oct 2004;21(5):525-33. [Medline].
Lin RL, Janniger CK. Pityriasis alba. Cutis. Jul 2005;76(1):21-4. [Medline].
Relyveld G, Menke H, Westerhof W. Progressive and extensive hypomelanosis and extensive pityriasis alba: same disease, different names?. J Eur Acad Dermatol Venereol. Nov 2006;20(10):1363-4. [Medline].
Thoma W, Kramer HJ, Mayser P. Pityriasis versicolor alba. J Eur Acad Dermatol Venereol. Mar 2005;19(2):147-52. [Medline].
Whitmore SE, Simmons-O'Brien E, Rotter FS. Hypopigmented mycosis fungoides. Arch Dermatol. Apr 1994;130(4):476-80. [Medline].
Further Reading
Keywords
pityriasis alba, PA, erythema streptogenes, furfuraceous impetigo, pityriasis sicca faciei, pityriasis simplex, pityriasis streptogenes, pityriasis alba, skin disorder, xerosis, atopic diathesis, hyperkeratosis, parakeratosis, hypopigmentation, atopic dermatitis, eczema, cheilitis, Dennie-Morgan infraorbital fold, wool intolerance, infra-auricular fissuring, contact dermatitis, tinea versicolor, vitiligo, nevus depigmentosus, psoriasis, tinea faciei, tinea corporis
