From the Research
Pityriasis rosea is a common, self-limiting skin rash that typically begins with a single "herald patch" followed by smaller scaly patches in a Christmas tree pattern on the trunk and proximal extremities, and most cases resolve spontaneously within 6-8 weeks without treatment. Diagnosis is primarily clinical, based on the characteristic appearance and distribution of the rash, with no specific laboratory tests required 1. The condition is characterized by a "herald patch" after which oval erythematous squamous lesions appear along Langer's lines of cleavage on the trunk and proximal extremities, giving it a "Christmas tree" appearance.
Diagnosis
- The diagnosis of pityriasis rosea is based on clinical and physical examination findings, with the presence of a herald patch and a generalized rash along the Langer lines being characteristic features 2.
- The differential diagnosis includes secondary syphilis, seborrheic dermatitis, nummular eczema, pityriasis lichenoides chronica, tinea corporis, viral exanthems, lichen planus, and pityriasis rosea-like eruption associated with certain medications.
Treatment
- For symptomatic relief of itching, topical treatments like calamine lotion, zinc oxide, or over-the-counter hydrocortisone 1% cream can be applied 2-3 times daily to affected areas.
- Oral antihistamines such as diphenhydramine (25-50mg every 6 hours) or cetirizine (10mg daily) may also help control itching.
- For severe cases with significant discomfort, oral acyclovir is recommended to shorten the duration of illness, as evidenced by recent studies 1.
- Patients should avoid hot showers and harsh soaps which can worsen symptoms, and use mild moisturizers.
- While the exact cause remains unclear, pityriasis rosea may be linked to human herpesvirus 6 or 7 reactivation, explaining its typically non-recurrent nature and self-limiting course.
Management
- Reassurance and symptomatic treatment should suffice in the vast majority of cases.
- Active intervention may be considered for individuals with severe or recurrent pityriasis rosea and pregnant women with the disease.
- Treatment options include acyclovir, macrolides (in particular, erythromycin), and ultraviolet phototherapy, with the choice of treatment depending on the severity of symptoms and the individual patient's needs 1.