eMedicine Specialties > Pediatrics: General Medicine > Dermatology

Pityriasis Alba: Differential Diagnoses & Workup

Author: Mark A Crowe, MD, Assistant Clinical Instructor, Department of Medicine, Division of Dermatology, University of Washington School of Medicine
Contributor Information and Disclosures

Updated: Oct 8, 2009

Differential Diagnoses

Atopic Dermatitis
Contact Dermatitis
Cutaneous T-Cell Lymphoma
Pityriasis Rosea
Tinea Versicolor

Other Problems to Be Considered

Hypopigmented mycosis fungoides
Nevus depigmentosus
Nummular eczema
Pigmenting pityriasis alba (PA)
Progressive and extensive hypomelanosis
Progressive macular hypomelanosis
Psoriasis
Seborrhea
Tinea corporis
Vitiligo

Hypopigmentation

Any inflammatory process that involves the skin, such as contact dermatitis, can leave areas of hypopigmentation upon healing. This may occur in other disorders, including those caused by fungi (eg, tinea versicolor), previous inflammatory conditions (ie, postinflammatory hypopigmentation), or idiopathic disorders (eg, vitiligo). Hypopigmentation may also result as a side effect of medications such as retinoic acid, benzoyl peroxide, and topical steroids. The most common disorders of hypopigmentation in children are pityriasis alba, vitiligo, nevus depigmentosus, and tinea versicolor.

Nevus depigmentosus

The localized form of nevus depigmentosus must be distinguished from an ash leaf spot, the earliest cutaneous manifestation of tuberous sclerosis, whereas the systematized form may be confused with hypomelanosis of Ito, another neurocutaneous disorder.

Nummular eczema

Nummular eczema is intensely pruritic.

Pigmenting pityriasis alba

This condition seems to be a variant of classic pityriasis alba, showing a strong association with dermatophyte infection, especially tinea capitis. It may be related to lichenoid melanodermatitis. The characteristic morphology of pigmenting pityriasis alba includes a central zone of bluish hyperpigmentation surrounded by a hypopigmented slightly scaly halo of variable width. Patients display lesions primarily on the face.

Psoriasis

In older children and adults, the early erythematous lesions of pityriasis alba may be mistaken for psoriasis; however, the distribution, the lack of psoriatic scales, and the sparing of scalp, elbows, and knees exclude this diagnosis.

Tinea versicolor

The lesions of tinea versicolor favor the upper trunk of adolescents. Potassium hydroxide examination of the associated scale reveals hyphal and yeast forms of Malassezia furfur.

Vitiligo

Vitiligo is an acquired progressive disorder, in contrast to nevus depigmentosus, which is a stable congenital leukoderma. The face is a common site for vitiligo, but the distribution is most commonly around the eyes or mouth, and, in contrast to pityriasis alba, the pigment loss is complete.

Workup

Laboratory Studies

  • The correct diagnosis of pityriasis alba (PA) is usually suggested by the age of the patient, fine scaling, hypopigmentation, and the distribution of lesions.
  • A potassium hydroxide (KOH) examination may be performed to rule out tinea versicolor, tinea faciei, or tinea corporis.

Histologic Findings

  • Skin biopsy is not usually necessary or particularly helpful in establishing the diagnosis. It may be indicated if the diagnosis of mycosis fungoides (cutaneous T-cell lymphoma) is a significant possibility.
  • Only a few histologic studies have been reported, and most maintain that the microscopic features of pityriasis alba are those of a mild chronic nonspecific dermatitis with decreased melanin production.3,1,4,5 A histopathologic diagnosis of pityriasis alba may be proposed when the following features are observed in a biopsy specimen taken from a characteristic skin lesion:
    • Irregular or markedly reduced pigment by melanin of the basal layer
    • No significant difference in melanocyte count between lesional and normal skin
    • Reduced number of active melanocytes and decreased number and size of melanosomes in affected skin

More on Pityriasis Alba

Overview: Pityriasis Alba
Differential Diagnoses & Workup: Pityriasis Alba
Treatment & Medication: Pityriasis Alba
Follow-up: Pityriasis Alba
Multimedia: Pityriasis Alba
References
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References

  1. 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].

  2. 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].

  3. 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].

  4. Vargas-Ocampo F. Pityriasis alba: a histologic study. Int J Dermatol. Dec 1993;32(12):870-3. [Medline].

  5. Martin RF, Lugo-Somolinos A, Sanchez JL. Clinicopathologic study on pityriasis alba. Bol Asoc Med P R. Oct 1990;82(10):463-5. [Medline].

  6. 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].

  7. 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].

  8. 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].

  9. 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].

  10. 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].

  11. 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].

  12. du Toit MJ, Jordaan HF. Pigmenting pityriasis alba. Pediatr Dermatol. Mar 1993;10(1):1-5. [Medline].

  13. 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].

  14. Lin RL, Janniger CK. Pityriasis alba. Cutis. Jul 2005;76(1):21-4. [Medline].

  15. 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].

  16. Thoma W, Kramer HJ, Mayser P. Pityriasis versicolor alba. J Eur Acad Dermatol Venereol. Mar 2005;19(2):147-52. [Medline].

  17. Whitmore SE, Simmons-O'Brien E, Rotter FS. Hypopigmented mycosis fungoides. Arch Dermatol. Apr 1994;130(4):476-80. [Medline].

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Further Reading

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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

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Contributor Information and Disclosures

Author

Mark A Crowe, MD, Assistant Clinical Instructor, Department of Medicine, Division of Dermatology, University of Washington School of Medicine
Mark A Crowe, MD is a member of the following medical societies: American Academy of Dermatology and North American Clinical Dermatologic Society
Disclosure: Nothing to disclose.

Medical Editor

Kevin P Connelly, DO, Clinical Assistant Professor, Department of Pediatrics, Division of General Pediatrics and Emergency Care, Virginia Commonwealth University; Medical Director, Paws for Health Pet Visitation Program of the Richmond SPCA; Pediatric Emergency Physician, Emergency Consultants Inc, Chippenham Medical Center
Kevin P Connelly, DO is a member of the following medical societies: American Academy of Pediatrics, American College of Osteopathic Pediatricians, and American Osteopathic Association
Disclosure: Nothing to disclose.

Pharmacy Editor

Mary L Windle, PharmD, Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy, Pharmacy Editor, eMedicine
Disclosure: Pfizer Inc Stock Investment from financial planner; Avanir Pharma Stock Investment from financial planner ; WebMD Salary and stock Employment and investment from financial planner

Managing Editor

Robert A Schwartz, MD, MPH, Professor and Head, Dermatology, Professor of Pathology, Pediatrics, Medicine, and Preventive Medicine and Community Health, UMDNJ-New Jersey Medical School
Robert A Schwartz, MD, MPH is a member of the following medical societies: Alpha Omega Alpha, American Academy of Dermatology, American College of Physicians, and Sigma Xi
Disclosure: Nothing to disclose.

CME Editor

Merrily P M Poth, MD, Professor, Department of Pediatrics and Neuroscience, Uniformed Services University of the Health Sciences
Merrily P M Poth, MD is a member of the following medical societies: American Academy of Pediatrics, Endocrine Society, and Lawson-Wilkins Pediatric Endocrine Society
Disclosure: Nothing to disclose.

Chief Editor

Dirk M Elston, MD, Director, Department of Dermatology, Geisinger Medical Center
Dirk M Elston, MD is a member of the following medical societies: American Academy of Dermatology
Disclosure: Nothing to disclose.

 
 
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