eMedicine Specialties > Emergency Medicine > Dermatology

Pityriasis Rosea: Differential Diagnoses & Workup

Author: Richard Lichenstein, MD, Director, Pediatric Emergency Medicine Research, Associate Professor, University of Maryland Medical Center
Contributor Information and Disclosures

Updated: Mar 27, 2008

Differential Diagnoses

Erythema Multiforme
Pityriasis Alba
Psoriasis
Syphilis
Tinea

Other Problems to Be Considered

Nummular eczema
Seborrheic dermatitis
Drug eruptions
Erythema dyschromicum perstans
Lichen planus
Lichenoid reactions
Pityriasis lichenoides
Kaposi sarcoma

Workup

Laboratory Studies

  • No diagnostic blood test is available.
  • Laboratory testing is usually unnecessary; however, a rapid plasma reagin (RPR) test should be drawn, as PR can be confused with secondary syphilis.
  • Blood profiles are normal; however, leucocytosis, neutrophilia, basophilia, and lymphocytosis have been seen.
  • Minimal increases in the erythrocyte sedimentation rate (ESR), total protein, albumin, alpha1-globulin, and alpha2-globulin have been noted.
  • Test findings for rheumatoid factor (RF), cold agglutinins, and cryoglobulins have been normal.

Procedures

  • A skin biopsy may be needed to diagnose pityriasis rosea (PR). Findings are nonspecific and are supportive of the diagnosis and can help rule out other conditions. A positive KOH preparation of a skin scraping of a herald patch can rule out tinea corpora. PR presents as superficial perivascular dermatitis with epidermal and dermal changes. More than half of specimens have epidermal cells that contain dyskeratotic degeneration.
    • The granular cell layer is reduced or absent.
    • Slight acanthosis and spongiosis may be present.
    • Microscopic vesicles may be present in a clinically dry lesion.
    • Superficial perivascular infiltration by lymphocytes, histiocytes and, rarely, eosinophils is present.
    • Extravasated red blood cells (RBCs) may be seen in the papillae and epidermis

More on Pityriasis Rosea

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

  1. Amer A, Fischer H, Li X. The natural history of pityriasis rosea in black American children: how correct is the "classic" description?. Arch Pediatr Adolesc Med. May 2007;161(5):503-6. [Medline].

  2. Drago F, Ranieri E, Malaguti F. Human herpesvirus 7 in patients with pityriasis rosea. Electron microscopy investigations and polymerase chain reaction in mononuclear cells, plasma and skin. Dermatology. 1997;195(4):374-8. [Medline].

  3. Sharma PK, Yadav TP, Gautam RK. Erythromycin in pityriasis rosea: A double-blind, placebo-controlled clinical trial. J Am Acad Dermatol. Feb 2000;42(2 Pt 1):241-4. [Medline].

  4. [Best Evidence] Amer A, Fischer H. Azithromycin does not cure pityriasis rosea. Pediatrics. May 2006;117(5):1702-5. [Medline].

  5. Stulberg DL, Wolfrey J. Pityriasis rosea. Am Fam Physician. Jan 1 2004;69(1):87-91. [Medline].

  6. Drago F, Vecchio F, Rebora A. Use of high-dose acyclovir in pityriasis rosea. J Am Acad Dermatol. Jan 2006;54(1):82-5. [Medline].

  7. Chuh A, Chan H, Zawar V. Pityriasis rosea--evidence for and against an infectious aetiology. Epidemiol Infect. Jun 2004;132(3):381-90. [Medline].

  8. Chuh A, Lee A, Zawar V. Pityriasis rosea--an update. Indian J Dermatol Venereol Leprol. Sep-Oct 2005;71(5):311-5. [Medline].

  9. Coustou D, Leaute-Labreze C, Bioulac-Sage P, et al. Asymmetric periflexural exanthem of childhood: a clinical, pathologic, and epidemiologic prospective study. Arch Dermatol. Jul 1999;135(7):799-803. [Medline].

  10. Hartley AH. Pityriasis rosea. Pediatr Rev. Aug 1999;20(8):266-9, quiz 270. [Medline].

  11. Horio T. Skin disorders that improve by exposure to sunlight. Clin Dermatol. Jan-Feb 1998;16(1):59-65. [Medline].

  12. Kay MH, Rapini RP, Fritz KA. Oral lesions in pityriasis rosea. Arch Dermatol. Nov 1985;121(11):1449-51. [Medline].

  13. Kempf W, Burg G. Pityriasis rosea--a virus-induced skin disease? An update. Arch Virol. 2000;145(8):1509-20. [Medline].

  14. Nanda A, Al-Hasawi F, Alsaleh QA. A prospective survey of pediatric dermatology clinic patients in Kuwait: an analysis of 10,000 cases. Pediatr Dermatol. Jan-Feb 1999;16(1):6-11. [Medline].

  15. Pomeranz AJ, Fairley JA. The systematic evaluation of the skin in children. Pediatr Clin North Am. Feb 1998;45(1):49-63. [Medline].

  16. Scott LA, Stone MS. Viral exanthems. Dermatol Online J. Aug 9 2003;9(3):4. [Full Text].

  17. Wyndham M. Pityriasis. Practitioner. Jun 1997;241(1575):358. [Medline].

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Further Reading

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Contributor Information and Disclosures

Author

Richard Lichenstein, MD, Director, Pediatric Emergency Medicine Research, Associate Professor, University of Maryland Medical Center
Richard Lichenstein, MD is a member of the following medical societies: Ambulatory Pediatric Association and American Academy of Pediatrics
Disclosure: Nothing to disclose.

Medical Editor

Jerry Balentine, DO, Professor of Emergency Medicine, New York College of Osteopathic Medicine; Senior Vice President, Chief Medical Officer, Medical Director, Attending Physician in Department of Emergency Medicine, Saint Barnabas Hospital
Jerry Balentine, DO is a member of the following medical societies: American College of Emergency Physicians, American College of Osteopathic Emergency Physicians, American College of Physician Executives, American Osteopathic Association, and New York Academy of Medicine
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, Associate Professor, Program Director, Department of Medicine, Division of Emergency Medicine, University of California at Los Angeles School of Medicine
Pamela L Dyne, MD is a member of the following medical societies: American College of Emergency Physicians and Society for Academic Emergency Medicine
Disclosure: Nothing to disclose.

 
 
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