Summary about Disease
Pityriasis rosea is a common skin rash that usually begins as a large, slightly raised, scaly patch called a "herald patch" on the chest, abdomen, or back. This is followed by a widespread eruption of smaller oval spots, often appearing in a "Christmas tree" pattern on the back. It is generally harmless and self-limiting, resolving on its own without treatment.
Symptoms
Herald Patch: A single, larger, slightly raised, oval or round, scaly patch. It is typically 2-10 cm in diameter and pink or salmon-colored.
Secondary Eruption: Numerous smaller (0.5-1.5 cm) oval or round spots that appear within a few days to weeks after the herald patch.
Distribution: The smaller spots often follow skin lines on the trunk, creating a "Christmas tree" pattern on the back.
Itch: The rash can be itchy, but the intensity varies from mild to severe.
Other Symptoms: Some people may experience fatigue, headache, sore throat, or fever before the rash appears, but these are uncommon.
Causes
The exact cause of pityriasis rosea is unknown. It is suspected to be triggered by a viral infection, possibly a type of herpesvirus (HHV-6 or HHV-7), but this is not definitively proven. It is not related to herpes simplex virus (the cause of cold sores and genital herpes).
Medicine Used
Treatment focuses on relieving symptoms, as the rash usually resolves on its own. Medications may include:
Antihistamines: To relieve itching (e.g., diphenhydramine, cetirizine, loratadine).
Topical Corticosteroids: To reduce inflammation and itching (e.g., hydrocortisone cream, triamcinolone cream).
Calamine Lotion: To soothe the skin and relieve itching.
Antiviral Medications: In severe cases or when symptoms are particularly bothersome, some doctors may prescribe antiviral medications (e.g., acyclovir), although their effectiveness is not consistently demonstrated.
Phototherapy (UVB light): May be used in some cases to speed up resolution of the rash.
Is Communicable
Pityriasis rosea is generally considered not contagious. While the exact cause is unknown, and a viral trigger is suspected, it does not typically spread from person to person. Recurrences are uncommon.
Precautions
Avoid harsh soaps and detergents: Use gentle, fragrance-free cleansers.
Moisturize regularly: Keep the skin hydrated with a fragrance-free moisturizer.
Avoid scratching: Scratching can worsen the rash and increase the risk of infection.
Avoid overheating: Excessive sweating can irritate the rash.
Sun exposure (in moderation): Brief, controlled exposure to sunlight may help reduce inflammation, but avoid sunburn.
How long does an outbreak last?
Pityriasis rosea typically lasts for 6 to 12 weeks, although it can sometimes persist for up to 5 months. In most cases, the rash clears up on its own without treatment.
How is it diagnosed?
Pityriasis rosea is usually diagnosed based on its characteristic appearance, particularly the herald patch and the "Christmas tree" pattern of the secondary eruption. A doctor may perform a physical examination and ask about symptoms. In some cases, a skin scraping or biopsy may be performed to rule out other conditions, such as ringworm or eczema.
Timeline of Symptoms
Phase 1 (Prodrome - Uncommon): Some individuals experience mild symptoms like fatigue, headache, sore throat, or fever, though this is not typical.
Phase 2 (Herald Patch): A single, larger patch appears, often mistaken for ringworm or eczema at first. This patch may be present for a few days to several weeks before the secondary eruption.
Phase 3 (Secondary Eruption): Smaller, oval or round spots erupt, typically starting on the trunk and spreading outwards. This phase can last for several weeks.
Phase 4 (Resolution): The rash gradually fades, and the skin returns to normal. Mild temporary skin discoloration (postinflammatory hypopigmentation or hyperpigmentation) may occur in some cases, especially in people with darker skin.
Important Considerations
Pregnancy: If you are pregnant and develop a rash suspected to be pityriasis rosea, consult your doctor promptly. Some studies have linked pityriasis rosea in pregnancy to an increased risk of miscarriage, particularly if it occurs early in pregnancy.
Differential Diagnosis: Several other skin conditions can mimic pityriasis rosea, including eczema, psoriasis, ringworm, and syphilis (secondary syphilis can present with a similar rash). Accurate diagnosis by a healthcare professional is essential.
Treatment is Symptomatic: Treatment primarily focuses on alleviating symptoms like itching. The rash will usually resolve on its own, regardless of treatment.
Recurrence: While rare, pityriasis rosea can recur in some individuals.