1.5.5 Pityriasis Rosea
Grading & Level of Importance: B
Pityriasis circinata; Gibert pityriasis; Pityriasis rosea Gibert.
Common disease (incidence 0.68/100 dermatology patients, prevalence 0.5-2%). Affects adolescents and young adults (aged 10 to 35 years).
Acute, disseminated, symmetrical exanthem with collarette scale.
Aetiology & Pathogenesis
Probably viral induction (human herpes virus 6 or 7).
Signs & Symptoms
The initial lesion is a large, flat erythematous (salmon coloured) plaque (herald patch (medallion), up to 5 cm in diameter), followed by multiple smaller lesions frequently following skin lines (e.g. Christmas tree distribution around ribs) with a typical collarette scale. Similar long axis orientation for individual plaque. Pruritus can occur (50%) and is variable in intensity, especially when skin is irritated by intense washing, sweating, or with simultaneous concurrent dermatitis. Prodromal symptoms (fever, headache, arthralgia, cough, vomiting, or lymphadenopathy) have been reported up to 60% of the patients.
Typically, on trunk (occasionally neck and proximal extremities).
Atypical variants can occur.
Laboratory & other workups
Not required. Corresponds to eczematous dermatitis; patchy lymphocytic infiltrate in the dermis and a few intraepidermal erythrocytes.
Self-limiting with spontaneous resolution after 4-8 weeks (possibly with hyperpigmentation but no scarring), can last longer.
Relapse rate up to 26% in 4 years.
- herald patch
- peripheral collarette scales
- predominant truncal and proximal limb distribution of the lesions, and
- orientation of lesions along the lines of cleavage
Prevention & Therapy
No evidence of any preventive measurements or effective treatment. Mild skin care and avoidance of irritating factors. If pruritic, topical antipruritic agents: weak corticosteroids or emollients. In selected cases narrow band UVB.
Relapses can especially occur in pregnancy. If in the first 15 weeks, close follow-up is required due to reported miscarriages.
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