eMedicine Specialties > Emergency Medicine > Dermatology

Pityriasis Alba: Differential Diagnoses & Workup

Author: Rashid M Rashid, MD, PhD, Post-Graduate Year 2 and House Staff Resident, Department of Dermatology, MD Anderson Cancer Center, University of Texas and The Morzak Center
Coauthor(s): Andrew C Miller, MD, Chief Resident and Clinical Assistant Instructor, Departments of Emergency Medicine and Internal Medicine, State University of New York Downstate Medical Center, Kings County Hospital Center; Mark A Silverberg, MD, FACEP, MMB, Assistant Professor, Assistant Residency Director, Department of Emergency Medicine, State University of New York Downstate College of Medicine; Consulting Staff, Department of Emergency Medicine, Staten Island University Hospital, Kings County Hospital, University Hospital, State University of New York Downstate at Brooklyn
Contributor Information and Disclosures

Updated: Jun 11, 2009

Differential Diagnoses

Dermatitis, Atopic
Dermatitis, Contact
Psoriasis
Tinea
Vitiligo

Other Problems to Be Considered

Mycosis fungoides: This is of particular concern for lesions that are atypical in any way. This includes lesions that are persistent, symptomatic, or changing in color or shape.

Leprosy: This condition also is critical to diagnose. This must be considered in arid regions, including areas with armadillo exposure in the United States. In particular, association with the 7 banded armadillo in the southern United States has been described.

Delusional tinea: Delusional disorders may result in chronic postinflammatory hypopigmentation changes. It may be possible for such a lesion to appear like pityriasis alba. 

Nevus depigmentosa: This tends to occur on the trunk, is segmental in distribution, and does not change in size or number over time.

Workup

Laboratory Studies

  • A workup may be undertaken to exclude other causes of hypopigmentation; however, most of this would be accomplished through a dermatology referral.
    • As an emergency physician, a Wood's light examination may help in evaluating the patient whose rash is due to vitiligo. Vitiligo will glow more brightly and will have edges with sharper demarcation.
    • Potassium hydroxide stain of a skin scraping will be positive if the patient has tinea versicolor, which has an alternate name of pityriasis versicolor. This would likely be performed by a dermatologist.
    • A biopsy would be required for atypical lesions as noted in the differential. This would likely be performed by a dermatologist.

Other Tests

  • Hypopigmentation may occur in other disorders, such as those caused by fungi (eg, tinea versicolor), previous inflammatory conditions (eg, postinflammatory hypopigmentation), idiopathic disorders (eg, vitiligo), or malignancy (mycosis fungoides), or it may occur secondary to medications such as retinoic acid, benzoyl peroxide, and topical steroids. Clinicians should rule out these other disorders when evaluating a patient who may have pityriasis alba.

Procedures

  • A biopsy of the lesions usually is not necessary and is not indicated in the emergency department. Pathologic findings are nonspecific; however, findings may include a basal layer with irregular pigmentation, follicular plugging, edema between epithelial cells (ie, spongiosis), or atopy of the sebaceous glands. However, this is required in atypical cases and should be performed in the office of a specialist in skin disease. It is of particular concern, considering the common location of the cheek and the potential approximation of this area to the facial artery.
  • Details of biopsy results are noted in Pathophysiology.

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. Vinod S, Singh G, Dash K, Grover S. Clinico epidemiological study of pityriasis alba. Indian J Dermatol Venereol Leprol. Nov-Dec 2002;68(6):338-40. [Medline].

  2. 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].

  3. 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].

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

  5. Ortonne JP, Passeron T. Melanin pigmentary disorders: treatment update. Dermatol Clin. Apr 2005;23(2):209-26. [Medline].

  6. Rakel RE, Bope ET. Conn's Current Therapy 2005. 57th ed. St Louis: WB Saunders; 2005:999.

  7. Sams WM. Principles and Practice of Dermatology. New York: Churchill; 1990:369.

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

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Further Reading

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Keywords

pityriasis alba, extensive pityriasis alba, hypopigmentation, hypopigmented dermatitis, scaly skin, white skin, atopic dermatitis, atopy, atopic disease, tinea versicolor 

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Contributor Information and Disclosures

Author

Rashid M Rashid, MD, PhD, Post-Graduate Year 2 and House Staff Resident, Department of Dermatology, MD Anderson Cancer Center, University of Texas and The Morzak Center
Rashid M Rashid, MD, PhD is a member of the following medical societies: American Academy of Dermatology, Council for Nail Disorders, Houston Dermatological Society, and Texas Medical Association
Disclosure: Nothing to disclose.

Coauthor(s)

Andrew C Miller, MD, Chief Resident and Clinical Assistant Instructor, Departments of Emergency Medicine and Internal Medicine, State University of New York Downstate Medical Center, Kings County Hospital Center
Andrew C Miller, MD is a member of the following medical societies: American College of Emergency Physicians, American College of Physicians, American Medical Association, Emergency Medicine Residents Association, Islamic Medical Association of North America, Medical Society of the State of New York, and Society for Academic Emergency Medicine
Disclosure: Nothing to disclose.

Mark A Silverberg, MD, FACEP, MMB, Assistant Professor, Assistant Residency Director, Department of Emergency Medicine, State University of New York Downstate College of Medicine; Consulting Staff, Department of Emergency Medicine, Staten Island University Hospital, Kings County Hospital, University Hospital, State University of New York Downstate at Brooklyn
Mark A Silverberg, MD, FACEP, MMB is a member of the following medical societies: American College of Emergency Physicians, American Medical Association, Council of Emergency Medicine Residency Directors, and Society for Academic Emergency Medicine
Disclosure: Nothing to disclose.

Medical Editor

David A Peak, MD, Assistant Residency Director of Harvard Affiliated Emergency Medicine Residency, Attending Physician, Massachusetts General Hospital; Consulting Staff, Department of Hyperbaric Medicine, Massachusetts Eye and Ear Infirmary
David A Peak, MD is a member of the following medical societies: American College of Emergency Physicians, American Medical Association, Society for Academic Emergency Medicine, and Undersea and Hyperbaric Medical Society
Disclosure: Nothing to disclose.

Pharmacy Editor

Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine
Disclosure: Nothing to disclose.

Managing Editor

Mark W Fourre, MD, Program Director, Department of Emergency Medicine, Maine Medical Center; Associate Clinical Professor, Department of Surgery, University of Vermont School of Medicine
Disclosure: Nothing to disclose.

CME Editor

John D Halamka, MD, MS, Associate Professor of Medicine, Harvard Medical School, Beth Israel Deaconess Medical Center; Chief Information Officer, CareGroup Healthcare System and Harvard Medical School; Attending Physician, Division of Emergency Medicine, Beth Israel Deaconess Medical Center
John D Halamka, MD, MS is a member of the following medical societies: American College of Emergency Physicians, American Medical Informatics Association, Phi Beta Kappa, and Society for Academic Emergency Medicine
Disclosure: Nothing to disclose.

Chief Editor

Pamela L Dyne, MD, Professor of Clinical Medicine/Emergency Medicine, David Geffen School of Medicine at UCLA; Attending Physician, Department of Emergency Medicine, Olive View-UCLA Medical Center
Pamela L Dyne, MD is a member of the following medical societies: American Academy of Emergency Medicine, American College of Emergency Physicians, and Society for Academic Emergency Medicine
Disclosure: Nothing to disclose.

 
 
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