eMedicine Specialties > Emergency Medicine > Dermatology

Pityriasis Rosea: Differential Diagnoses & Workup

Author: Richard Lichenstein, MD, Associate Professor, Pediatric Emergency Department, University of Maryland School of Medicine
Contributor Information and Disclosures

Updated: Dec 8, 2009

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 testing is available for pityriasis rosea (PR).
  • Laboratory testing is usually unnecessary; however, a rapid plasma reagin (RPR) test should be drawn because pityriasis rosea 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. Findings are nonspecific and are supportive of the diagnosis and can help rule out other conditions. A positive potassium hydroxide (KOH) preparation of a skin scraping of a herald patch can rule out tinea corpora.
  • Pityriasis rosea 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 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
Multimedia: Pityriasis Rosea
References
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References

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  2. 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].

  3. 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].

  4. Drago F, Broccolo F, Rebora A. Pityriasis rosea: an update with a critical appraisal of its possible herpesviral etiology. J Am Acad Dermatol. Aug 2009;61(2):303-18. [Medline].

  5. Drago F, Rebora A. Treatments for pityriasis rosea. Skin Therapy Lett. Mar 2009;14(3):6-7. [Medline].

  6. 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].

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

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

  9. 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].

  10. [Guideline] Finnish Medical Society Duodecim. Syphilis. In: EBM Guidelines. Evidence-Based Medicine [Internet]. Helsinki, Finland: Wiley Interscience. John Wiley & Sons; 2008 Jun 6. [Full Text].

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

  13. 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].

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

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

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Further Reading

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Keywords

pityriasis rosea, PR, pityriasis rosea gigantica, pityriasis rosea urticata, papular PR, atypical PR, drug-induced PR, keratosis, vesicular PR, herald patch, rash, pruritus, exanthem, treatment, symptoms

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Contributor Information and Disclosures

Author

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

Medical Editor

Jerry Balentine, DO, Professor of Emergency Medicine, New York College of Osteopathic Medicine; Executive Vice President, Chief Medical Officer, Attending Physician in Department of Emergency Medicine, St. 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: eMedicine Salary Employment

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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