Pityriasis Rosea

By : Fatimah Bassem AlshiekhGroup: B2

What is pityriasis rosea?Pityriasis rosea is a viral rash which lasts about 6–12 weeks. It is characterised by a herald patch followed by similar, smaller oval red patches that are located mainly on the chest and back.

Pityriasis Rosea (PR)the name means “fine

pink scale”.

Etilogy

Infectious agent

(HHV-)7 and HHV-6

influenza virusH1N1

Drugs(Drug-induced PR) 

clozapine D-penicillamine

 the search for an infectious cause of PR has been unsuccessful.

Epidemiology

-Worldwide, pityriasis rosea has been estimated to account for 2% of dermatologic outpatient visits. The disease is more common in the spring and the fall in temperate climate zones. However, it may be more frequent in the summer in some other regions. It

favors the hot, dry season in Australia ,India, and Malaysia.

  -most common in persons aged 10-35 years.  -The female-to-male ratio is reported as 2:1

Presentation History ASK about:

1 -Close contacts with similar eruptions.2-Medication intake.

3 -Previous sexually transmitted disease.4 -Possible pregnancy.

5  -previous PR.6 -Recent upper respiratory tract infection.

Presentation

Initially single pink macule or patch which gradually expands over a few days to become an oval or round plaque that is 2-10 cm in diameter, generally with a central wrinkled salmon-colored area and a dark red peripheral zone. This lesion, referred to as the herald patch.

THEN Subsequent lesions A generalized eruption then occurs, in which numerous lesions develop in crops over a period of 1-2 weeks (typically about 10 days) after the onset of the herald

patch .

characteristic feature is the collarette appearance of the scale, with edges peripherally attached and lifted up near the center of the lesion.

Differential DiagnosesDrug EruptionsErythema Annulare CentrifugumErythema Dyschromicum PerstansErythema MultiformeKaposi SarcomaLichen PlanusNummular DermatitisParapsoriasisPityriasis Alba in Emergency MedicinePityriasis LichenoidesPityriasis Rubra PilarisPsoriasis, GuttateSeborrheic DermatitisSyphilisTinea CorporisTinea Versicolor

In a patient who has a pityriasis-type rash and risk factors for sexually transmitted diseases (eg, intravenous [IV] drug use, HIV infection, or promiscuity), syphilis should be considered to be present until

proved otherwise .

Investigation

-The diagnosis of pityriasis rosea (PR) is made clinically in most cases. In general, laboratory tests are not necessary. 

 

Investigation

-The diagnosis of pityriasis rosea (PR) is made clinically in most cases. In general, laboratory tests are not necessary. 

-Because PR can be confused with secondary syphilis, a rapid plasma reagin (RPR) test should be performed to rule out this condition.

-potassium hydrochloride (KOH) test may be especially useful for helping to diagnose tinea corporis .

-Skin biopsy 

Treatment of pityriasis roseaGeneral adviceBathe or shower with plain water and bath oil, aqueous cream, or other soap substitute.Apply moisturizing creams to dry skin.Expose skin to sunlight cautiously (without burning).

Prescription treatmentsA 7-day course of high-dose aciclovirA 2-week course of oral erythromycin has also been reported to help, probably because of a nonspecific anti-inflammatory effect. Other studies have found that erythromycin and azithromycin are not effective in pityriasis rosea.

Topical steroid cream or ointment may reduce the itch while waiting for the rash to resolve.

PhototherapyExtensive or persistent cases can be treated by phototherapy (ultraviolet light, UVB)

Clinical case 27 years old woman complains of pink multy patches in

her chest for two weeks . It start with one patch 3-5cm harled plaque . And it is very itchy.

1-describe the lesion. 2-what is the diagnosis?

3-what is the deferential diagnosis? 4-what is the investigation?

5 -what is the treatment ?

References: . .www dermnetz org. .www medscape com. .www add org

Thank you