eMedicine Specialties > Pediatrics: General Medicine > Dermatology

Pityriasis Rosea

Author: Maria R Nasca, MD, PhD, Assistant Professor, Department of Dermatology, University of Catania School of Medicine, Italy
Coauthor(s): Giuseppe Micali, MD, Head, Professor, Department of Dermatology, University of Catania School of Medicine, Italy
Contributor Information and Disclosures

Updated: Sep 24, 2009

Introduction

Background

Pityriasis rosea (PR) was first described by Camille Melchior Gilbert in 1860. The term pityriasis rosea means fine pink scale. It is a common skin disorder observed in otherwise healthy people, most frequently children and young adults. Pityriasis rosea manifests as an acute, self-limiting, papulosquamous eruption with a 6-week to 8-week duration. It may sometimes occur in atypical variants or may mimic other skin disorders, such as secondary syphilis.^1,2 Guidelines for diagnosing syphilis (and distinguishing the roseola from pityriasis rosea) have been established.³

Pathophysiology

The disease has been associated with recent upper respiratory infections. Increased incidence among groups with close physical contact (eg, families, students, military personnel) has been reported. A higher incidence among patients with decreased immunity (eg, pregnant women, bone marrow transplant patients) has also been noted. Additionally, ampicillin has been found to increase the distribution of the eruption; this phenomenon bears a striking resemblance to the effect of ampicillin on the rash of infectious mononucleosis. Finally, some immunological findings, including the presence of immunoglobulin (Ig)M directed against keratinocytes or the increase of Langerhans cells and CT4 T lymphocytes in the dermal infiltrate of patients with pityriasis rosea also support the pathogenetic role of a transmissible agent.

Many common infectious microorganisms have been considered (eg, influenza A and B; parainfluenza I, II, and III; Epstein-Barr virus; parvovirus B19; cytomegalovirus; herpesviruses 1, 2, and 8; Mycoplasma) and have been shown not to be causative. Recent reports using polymerase chain reaction (PCR) analysis have suggested a role for human herpesvirus (HHV)-7 and HHV-6 but this has not been confirmed in later studies.^{4,5,6,7,8,9,10,11}

Despite the prevailing opinion that pityriasis rosea is caused by an infectious agent, it does not appear to be very contagious; household contacts and schoolmates usually do not develop the disease.

Pityriasis rosea–like eruptions can also occur in association with many drugs. These include acetylsalicylic acid, barbiturates, bismuth, captopril, clonidine, gold, imatinib, isotretinoin, ketotifen, levamisole, metronidazole, omeprazole, D-penicillamine, terbinafine, and Bacillus Calmette-Guérin or diphtheria vaccine. Adalimumab has also been implicated.¹² Drug-induced pityriasis rosea often lasts longer than non–drug-induced pityriasis rosea.

Frequency

United States

An estimated frequency of 0.13-0.14% has been reported, with a 0.3-3% prevalence at dermatologic centers.

International

Pityriasis rosea accounts for approximately 2% of outpatient visits in dermatology. It is present worldwide and occurs year round, although it may be more common in the fall and spring. In some geographic areas, such as India, Malaysia, and Australia, it may be more frequent in the dry hot season.

Mortality/Morbidity

Pityriasis rosea is a self-limiting, benign disorder with a recurrence rate of less than 3%. It usually lasts for 6-8 weeks but can last as long as 3-6 months. Postinflammatory pigment changes are common, especially in black people. Bacterial superinfections are rarely observed. In pregnant women, it has sometimes been associated with miscarriage (if occurring within the first 15 wk of pregnancy), or premature delivery, neonatal hypotonia and hyporeactivity.¹³

Race

Pityriasis rosea shows no racial specificity, although black people may have more extensive or atypical disease. The lesions may show a dark hue and lack the erythematous component.

Sex

Pityriasis rosea occurs slightly more often in females than in males. The female-to-male ratio is reported as 2:1 or 3:2 in the United States.

Age

Pityriasis rosea is observed in people of all age groups, although it is most common in persons aged 10-35 years. The youngest patient reported in the literature was aged 3 months, and the oldest was aged 85 years.

Clinical

History

• A small number of patients (5%) with pityriasis rosea (PR) have mild prodromal symptoms, such as malaise, fatigue, headache, nausea, anorexia, chills, fever, and arthralgias. Lymphadenopathy may occur prior to onset of the rash.
• Some patients (8-20%) may have a history of recent upper respiratory infection. Patients should also be asked about recent medication intake or close contacts with similar eruptions.
• Rash may be pruritic (25-75% of cases), especially in the first few weeks of the illness.
• Approximately 50-80% of patients present with a herald patch.

Physical

• Primary herald patch
  • A herald patch is a pink macule or papule that gradually expands over a few days to become a 2-cm to 10-cm, salmon-pink–to–brown, oval plaque. The lesion usually shows a collarette of fine scales just inside its well-demarcated edges and may exhibit central clearing, which mimics tinea corporis.
  • Primary herald patch is most commonly observed on the trunk, neck, and proximal extremities.
• Subsequent lesions
  • Numerous subsequent lesions occur in crops 1-2 weeks (range 1-30 d) after onset of the herald patch and symmetrically involve the thorax, back, abdomen, and proximal extremities. They are not usually observed on the face, hands, and feet.
  • These lesions occur as macules and papules that are elliptical or ovular in shape and 0.5-1.5 cm across. Fine scaling and central wrinkling, with a cigarette paper aspect, is usually present. A characteristic feature is the collarette appearance of the scale, with edges peripherally attached and lifted up near the center of the lesion. However, unlike classic tinea corporis, the scale does not extend to the border of the lesion.
  • The distribution is usually bilateral and diffuse, with the long axis of the lesions running parallel to skin tension lines. This produces a "Christmas tree" pattern on the back.
• Pigment changes: With resolution of the eruption, postinflammatory pigment changes can be observed.
• Oral findings: Oral lesions are infrequently observed (10-16% of cases) but may include plaques, petechiae, papules, blisters, and ulcers (with or without raised borders).
• Variants and atypical forms
  • Approximately 20% of patients present with atypical forms of pityriasis rosea.
  • The herald patch may be absent in 10-50% of the cases, a finding that is more frequently observed in drug-induced pityriasis rosea. Alternatively, it may occur as multiple lesions or in atypical locations, such as the soles.¹⁴ Sometimes, it is the only manifestation of the disease and is not followed by the typical rash.
  • The generalized rash may occasionally spread to the face, hands, and feet. The face may be more commonly affected in young children, pregnant women, and black people. In such cases, the physician should consider secondary syphilis in the differential diagnosis, especially when involvement of the palms and soles is present.
  • An inverse pattern may also occur, with most of the lesions limited to the face and extremities. This happens more frequently in children than in adults.
  • Sometimes, lesions may be limited to single body areas, such as the abdomen, or show a unilateral distribution.
  • A morphologic variant characterized by atypical large patches, that tend to be fewer in number and coalescent, has been described as pityriasis circinata et marginata of Vidal.
  • A predominantly papular form is believed to occur more commonly in young children, pregnant women, and black people.
  • Lesions can also be vesicular, pustular, urticarial, purpuric, or even erythema multiform–like, making the diagnosis difficult.^15,16
  • Secondary eczematous changes can occur if pruritus is severe.
  • Black people tend to show more often widespread forms and concurrent lymphadenopathy, with hyperpigmentation upon resolution. Black children have also been found to more frequently develop papular lesions (33%), scalp (8%) and facial (30%) involvement, and a shorter course, with resolution within 2 weeks.¹⁷

Causes

• See Pathophysiology.

• Search for CME/CE on This Topic »

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• Pityriasis Rosea (Dermatology)
• Pityriasis (Infectious Diseases)

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