Pityriasis Rosea

Synonyms

Pityriasis circinata; Gibert pityriasis; Pityriasis rosea Gibert.

Epidemiology

Common disease (incidence 0.68/100 dermatology patients, prevalence 0.5-2%). Affects adolescents and young adults (aged 10 to 35 years).

Definition

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.

Localisation

Typically, on trunk (occasionally neck and proximal extremities).

Classification

Atypical variants can occur.

Laboratory & other workups

Not necessary.

Dermatopathology

Not required. Corresponds to eczematous dermatitis; patchy lymphocytic infiltrate in the dermis and a few intraepidermal erythrocytes.

Course

Self-limiting with spontaneous resolution after 4-8 weeks (possibly with hyperpigmentation but no scarring), can last longer.

Complications

Relapse rate up to 26% in 4 years.

Diagnosis

Clinical.

Criteria:

herald patch
peripheral collarette scales
predominant truncal and proximal limb distribution of the lesions, and
orientation of lesions along the lines of cleavage

Differential diagnosis

Secondary syphilis, drug reactions, tinea, psoriasis parapsoriasis, nummular eczema.

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.

Special

Relapses can especially occur in pregnancy. If in the first 15 weeks, close follow-up is required due to reported miscarriages.

1.5.5 Pityriasis Rosea