Pityriasis Rosea, also known as Pityriasis Rosea Gibert  is a common and self-limiting type of skin rash commonly seen in older children and young adults, but may occur at any age. Pityriasis Rosea may be seen at anytime of the year, but is most common during spring and fall.

Pityriasis Rosea Causes

The cause of pityriasis Rosea is unclear, but the data provided by many epidemiologic, experimental, and clinical  studies suggest an infectious origin. Pityriasis rosea is not a sign of any internal disease, nor is it caused by a fungus, a bacteria, or an allergy. All available evidence suggest that it may be more likely due to reactivation of human herpesviruses (HHV-6 and -7 ). We could say that, it is probably a multifactorial disease that can be induced by various infectious agents.

Pityriasis Rosea Symptoms:

Prodromal Symptoms
Though not reported in every patients, most of the patients may complain of nausea, malaise, loss of appetite, headache, fever, irritability, upper respiratory symptoms ( sore throat), gastrointestinal symptoms, joint pain and swelling of lymph nodes before the cutaneous sign appear.

Cutaneous Eruption

Primary Eruption:
Usually, Pityriasis rosea rash begins with a single, large, round or oval, scaly, pink patch on the chest, neck, abdomen, back or extermities which is called a “herald” or “mother” patch. But sometimes it may also occur as multiple lesions or in atypical locations, which may be often confused with other infection like tinea, psoriasis or secondary syphilis. The Herald patch is paler and slightly depressed or wrinkled in the centre and slightly elevated, dark red and scaly in the periphery. The patch enlarge progressively reaching 3 cm or more in diameter and remains isolated for about 2 weeks or more after which secondary generalized eruption appears.

Secondary Eruption:
This secondary eruptive phase starts 1-2 weeks after the herald patch is seen. (Although in few cases it may occur from hours to months after herald patch is seen). This phase is characterized by eruption of patches that looks similar to the initial one and are smaller and symmetrically oriented seen predominantly on the trunk, the abdomen, back, and the proximal upper extremities. These are salmon-colored, oval macules or patches ranging from 0.5 to 1.5 cm in diameter, with collarette scale, often described as cigarette paper like appearance. They may usually form a christmas tree like pattern at the back. Pruritus may occurs in 75% of patients and may be severe in 25%. Warm environment, bathing in hot water or physical activities like running may worsen the itching and the rashes.

Atypical Pityriasis Rosea:

Atypical pityriasis rosea occurs in 20% of patients. They may be atypical for their size, number, distribution, morphology, location, severity and course. These atypical pityriasis rosea may be associated with missing herald patch or multiple herald patch, peripheral distribution, and may be localized in a area like abdomen, axilla, face, groin, distal extremities, the palm and the soles. Atypical presentations are usually seen in younger children then in adults.

Oral Involvement
Oral lesions are not commonly seen in PR. If there is oral involvement, hemorrhagic spots, ulcers, papules, vesicles, bullae, or erythematous plaques may be seen. Study suggests that they may be more common to occur in dark skinned people. They usually disappear along with the cutaneous lesion or few days later.

Pityriasis Rosea in Pregnancy
Pityriasis Rosea has been reported to occur more frequently in pregnancy than in the general population (18% vs 6%). PR may result in spontaneous abortion, premature delivery with neonatal hypotonia, especially if it develops before 15 weeks of gestation.

Laboratory Findings in Pityriasis Rosea:

Laboratory findings in PR may usually be in normal range, so it will not help in diagnosis. If its an atypical case or hard to differentiate one can perform lab test to rule out other possible disease.
Syphilis: Screening rapid Plasma Reagin ( RPR) test or VDRL , if required HIV test can be performed.
Tinea: KOH test
Nummular dermatitis, Guttate psoriasis : perform a biopsy.

Other possible diagnosis one may consider:

  • Guttate Psoriasis
  • Lichen Planus
  • Nummular Dermatitis
  • Seborrheic Dermatitis
  • Secondary Syphilis
  • Pityriasis lichenoides
  • Tinea Corporis
  • Erythema Dyschromicum Perstans
  • Other Viral exanthems
  • Primary human immunodeficiency viral infection
Excluding Common disease

Secondary syphilis: In secondary syphilis there may be history of primary chancre, no herald patch are seen, lesion usually involves palms and soles, condyloma lata may be present and they are usually associated with other systemic complaints and lymphadenopathy. It can be confirmed by serology test like RPR or VDRL
Tinea corporis: In Tinea corporis scale is usually at periphery of plaques, plaques are usually not oval and distributed along the lines of cleavage. It can be confirmed by KOH examination.
Nummular dermatitis: In Nummular dermatitis, plaques are usually circular and not oval, no collarettes of scale occurs, tiny vesicles are common. It can be excluded by biopsy
Guttate psoriasis: In Guttate psoriasis, plaques usually are smaller than PR plaques and do not follow lines of cleavage, scale is thick and not fine. It can be excluded by Biopsy
Pityriasis lichenoides chronica: It has longer disease course, smaller lesions, thicker scale, with no herald patch and more common on extremities. It can be excluded by biopsy.
PR-like drug eruption: It can be excluded by obtaining drug history.

Association of Pityriasis Rosea:

PR has been associated with prior history of upper respiratory infection, asthma and eczema. Several research papers have associated PR like eruption in neoplasms ( those of gastric, bronchogenic), T-cell lymphomas, hodgkin disease, bone marrow transplantation. PR is a common disease, so these association may just be a coincidence by chance or it may also be due to the reactivation of latent virus triggered by the immunologic changes.

Pityriasis Rosea Treatment

In most cases, Pityriasis rosea will usually go away on its own within four to six weeks. No specific treatment are recommended on the basis of evidence based medicine. In some atypical and severe cases treatment can be prescribed accordingly. So treatment modalities are mainly focused on controlling itching and symptomatic relief.

Controlling the itch:

  • Oral Antihistamines: Cetrizine, fexofenadine, chlorpheniramine, loratadine.
  • Soothing lotions like calamine lotions.
  • Low or mild potent steroids Creams or ointments. ( in some cases topical steroids may cause the eruption to generalize to erythroderma).
  • Steroids and antihistamines doesn’t speedup the disease recovery but will control discomfort.
  • Avoiding soaps, avoiding hot water bath and use of moisturizing creams is needed.

Treatment of Pityriasis Rosea Rash

  • Low to mild potency steroids may be used.
  • Systemic steroids are not recommended, until and unless required for some very severe cases.
  • Systemic steroids will not shorten the disease progression, in fact they might even prolong or exacerbate the disease.
  • Patients with associated flu-like symptoms or with extensive skin rash may be given early course of oral Acyclovir or its derivatives . This may reduce the duration of PR by one or two weeks.
  • Light therapy either Ultraviolet B or brief introduction to sunlight may be beneficial to some patients. But are are few possibility of post-inflammatory pigmentation with light therapy.
  • Antibiotics like erythromycin and azithromycin and other macrolides have been tried without much success. They were thought to shorten the disease course.