Pityriasis rosea

Harmless and common skin condition with characteristic ‘medallions’, yellow on the inside with a red edge, usually scaly. A few days after the first patch appears smaller patches occur all over the rump, usually less distinct, but probably also with the ‘medallion’ effect. The cause is unknown; viral origin is suspected but unproven. The condition heals spontaneously after 6 to 8 weeks, and causes no difficulty other than skin abnormalities, thus no treatment is necessary.