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.
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.
The exact cause is unknown, though the following factors may be relevant:
Infection - A relationship with recent upper respiratory tract infections has been recorded, and some studies have demonstrated the presence of HHV 7 (human herpesvirus).
Cell-Mediated Immunity (CMI) - CMI has been implicated.
Drugs - Metronidazole, Gold, Isotretinoin, Captopril, Bismuth, Arsenic, Barbiturates, Clonidine, and Omeprazole have been reported to cause pityriasis rosea or pityriasis rosea-like rashes, often with atypical features and a protracted course. Pityriasis rosea like eruptions can also occur following hepatitis B and BCG vaccination (Bacillus Calmette-Guerin).
Other Factors - Atopy, seborrheic dermatitis, and acne vulgaris are more common in patients with 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:
Vesicular pityriasis rosea presents as a generalized eruption of 2 mm to 6 mm vesicles or as a rosette of vesicles mainly over the head, soles, and palms. It is commonly seen in children.
Purpuric pityriasis rosea is also called hemorrhagic pityriasis rosea presents as macular purpura on skin or oral mucosa.
Urticarial pityriasis rosea.
Generalized papular pityriasis rosea is seen in pregnant women, young children, and African Caribbeans. It occurs rarely and presents as multiple papules.
Lichenoid pityriasis rosea is observed in the course of atypical pityriasis rosea, but it is more commonly caused by drugs such as Gold, Captopril, Barbiturates, D-penicillamine, and Clonidine.
Erythema multiforme-like pityriasis rosea presents with targetoid lesions along with the classical lesions of pityriasis rosea.
Follicular pityriasis rosea are the secondary lesions, which are typically follicular and are present as discrete or in groups associated with classical lesions.
Giant pityriasis rosea consists of plaques and circles of very large sizes ranging from 5 cm to 7 cm, with individual lesions reaching the size of the palm of the patient.
Inverse pityriasis rosea lesions are predominantly present in acral and flexural areas involving the axilla, groin, and face.
Acral pityriasis rosea lesions are more concentrated over acral parts of the body, that is, palms, and soles, where EM, syphilis, necrolytic acral erythema, and drug eruptions should be kept as differentials.
Unilateral pityriasis rosea can be seen in both children and adults and is a rare variant.
Blaschkoid pityriasis rosea: Lesions of pityriasis rosea follow the lines of Blaschko.
Limb-Girdle pityriasis rosea is also known as pityriasis rosea of Vidal, where eruptions are limited to shoulders or pelvic girdle, thus involving axilla and groin. Lesions are usually larger and more annular.
Mucosal involvement in pityriasis rosea is seen in 16% of patients affecting the oral mucosa, with punctuate, erosive, bullous, hemorrhages, ulcers (with or without raised borders), petechiae, papulovesicular, bullae, and erythematous plaques.
Localized pityriasis rosea: Eruptions are localized to one part of the body.
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.
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).
Because pityriasis rosea is a self-limiting disease, a patient should be reassured regarding the innocuous and self-limiting nature of the disease.
Exposure to natural or artificial sunlight helps to fade the rash. Light therapy causes lasting darkening in some spots, even after the rash clears.
There is no need for active treatment in mild or uncomplicated cases.
In the event of itching, zinc oxide or calamine lotion with antihistamines will suffice.
In the widespread, severe, and vesicular pityriasis rosea, topical corticosteroids like Clobetasol, Halobetasol, Mometasone, and Fluticasone, depending on the location and severity of lesions, are indicated. Dapsone and ultraviolet radiation have also been used in such cases.
In order to help relieve the discomfort of pityriasis rosea, the following tips should be followed,
Take over-the-counter (OTC) allergy medicine (antihistamines) such as Diphenhydramine (like Benadryl).
Take a bath or shower with lukewarm water.
Bathe with the oatmeal bath and the oatmeal bath products are available at the pharmacy.
Apply a calamine lotion, moisturizer, or over-the-counter corticosteroid cream following a bath or face wash.
Last reviewed at:
11 Oct 2021 - 5 min read
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