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Pityriasis Rosea, a Common Papulosquamous Disorder

Written by
Dr. Suvash Sahu
and medically reviewed by iCliniq medical review team.

Published on Jan 23, 2017 and last reviewed on Oct 11, 2021   -  5 min read

Abstract

Pityriasis rosea is a rash that begins as an oval or large circular spot on the chest, back, or abdomen. It is called a herald patch, and it can be up to 10 centimeters. Please read the article to know more.

Contents
Pityriasis Rosea, a Common Papulosquamous Disorder

Introduction:

Pityriasis rosea is named from a Greek word, pityriasis (fine-scale), and Latin word Rosea (rose red) with common Christmas tree or fir tree pattern.

Pityriasis rosea (PR) will develop suddenly. It is a self-limiting eruption, which means it will subside on its own after a specified duration if not treated. It runs a unique and constant course lasting about six weeks.

What Are the Causes of Pityriasis Rosea?

The exact cause is unknown, though the following factors may be relevant:

What Are the Clinical Manifestations of Pityriasis Rosea?

In classic pityriasis rosea, the primary eruptions, also called herald patch or mother patch, are seen in 50% to 90% of cases on their covered truncal area. It reaches a diameter of a few centimeters within a few days. It is oval or round with a central, wrinkled, salmon-colored area and a darker red peripheral zone separated by a collarette of fine scales. Secondary eruption follows the herald plaque by two days to two months. It appears in crops and reaches its maximum size in about 10 days. The symmetric eruption covers the trunk, adjacent neck, and proximal parts of the extremities lasting for about 2 to 10 weeks. However, the eczematous or drug-induced eruptions may take longer to clear.

In the typical secondary rash, eruptions smaller than the primary plaque co-exist. Small plaques resemble the herald patch in miniature, along with the lines of cleavage. On the trunk, it is present with a Christmas tree pattern, and on the back in a chevron pattern. There will be small, red, and usually non-scaling papules. Itching is severe in 25% of the cases, slight or moderate in 50%, and absent in 25%.

Atypical pityriasis rosea (20%) variants may either be primary or secondary rash. Herald patch fails or does not appear at all. Sometimes, two or more herald patches appear. The secondary eruption may not appear at all or is restricted to the extremities. It is not present on the trunk (pityriasis rosea inverse),; however, involves the face, which is not a usual site, especially in children. It may be vesicular, pustular, urticaria-like, or purpuric, mainly in children. It is rarely localized or unilateral. Sometimes, there will be large lesions, confluent in a circinate pattern (rolled up leaves as in fern). The various atypical types include:

What Is the Prognosis and Prevalence of the Disease?

Course and Prognosis:

Usually self-limiting, lesions fade after 3 to 6 weeks, sometimes leaving residual hypo and hyperpigmentation, which is entirely reversible. Recurrences are unusual and may occur in 2% of the cases. Black races are more prone to recurrent pityriasis rosea.

Prevalence of Disease:

The prevalence of pityriasis rosea in the total population has been calculated as 0.12% in men and 0.15% in women, mostly in the age group of 10 to 44 years; even infant cases have been recorded. According to temperature and climate, the incidence is more in winter, though, in a few countries, it is seen more often in the hot and dry season.

How Is Pityriasis Rosea Diagnosed?

Pityriasis rosea is diagnosed by taking the blood test, and the blood picture is usually standard, but leukocyte count can be raised. The neutrophil and eosinophil counts may also rise occasionally.

In most cases, the doctor identifies pityriasis rosea by looking at the rash. The doctor takes a small scraping of the rash for testing because this condition can sometimes be confused with tinea corporis (ringworm).

What Is the Differential Diagnosis of Pityriasis Rosea?

How Is Pityriasis Rosea Treated?

What Are the Home Remedies for Pityriasis Rosea?

In order to help relieve the discomfort of pityriasis rosea, the following tips should be followed,

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Last reviewed at:
11 Oct 2021  -  5 min read

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