"Pityriasis Rosea" (My Synopsis)

Pityriasis Rosea, by DANIEL L. STULBERG, M.D., Utah Valley Regional Medical Center, Provo, Utah JEFF WOLFREY, M.D., Good Samaritan Regional Medical Center, Phoenix, Arizona
Am Fam Physician. 2004 Jan 1;69(1):87-91.

     Pityriasis rosea is an acute rash of uncertain origin. Community outbreaks occur in clusters. Recurrence is rare, which suggests immunity. It appears to be viral, but no connection or proof has been found. It occurs mostly in children and young adults in either gender.  The first symptom is that of a generalized viral URI. Then comes the herald patch on the trunk. It is a large, round, red, raised, scaly, collarette lesion. It can easily be mistaken for eczema. Over the next few days to weeks, similar smaller (0.5-1cm) lesions start to appear over the trunk.  These lesions typically follow a "christmas tree" pattern on the back because they follow the langer lines of the skin. It looks like a V shaped pattern if present on the chest or a horizontal pattern on the abdomen. The extremities are spared. Pruritis is variable, but it is intense in a quarter of the patients. Topical treatment for the itching is effective, but oral antihistamines or steroids are an option. One study had shown that treatment with two weeks of erythromycin will resolve the rash. UV light has also helped with the rash and itching. The disease will usually resolve on its' own within 5-8 weeks. A rash lasting greater than three months may be a misdiagnosis. The differential includes tinea corporis, pityriasis lichenoides, viral exanthem, lichen planus, medication reaction, or syphilis (rash on palms and soles).