(1997; 132 pages) [French] [Spanish]
Pityriasis rosea is a common self-limiting dermatosis that is probably of viral origin. It is characterized by the appearance of an annular, erythematous scaly lesion (herald patch) on the trunk, neck or upper limb. On rare occasions, this lesion may be preceded by a prodromal episode of malaise, headache and sore throat. Within a few days, a symmetrical rash often indistinguishable from that of secondary syphilis (but mildly pruritic) becomes apparent, usually on the back. The rash usually persists for 6 weeks, although it may last for as long as 12 weeks. In dark-skinned persons post-inflammatory hyperpigmentary changes may be permanent.
Specific treatment is neither available nor necessary. If the diagnosis is in doubt, a serological test to exclude the possibility of syphilis should be undertaken. Topical application of calamine lotion or 1% hydrocortisone acetate may help to relieve pruritus. Exposure to the sun or ultraviolet light may also be beneficial.