Pityriasis rosea is an acute exanthem of unknown etiology that is self-limiting and resolves within one to three months. It is a common skin disorder with distinctive erythematous oval scaly eruption of the trunk and limbs, characterized by a herald patch followed by the appearance of secondary lesions of Langer’s lines pattern. The rash typically lasts five weeks; it resolves within eight weeks in 80 percent of patients but can last for five months. After remission, hyperpigmentation or hypopigmentation could occur but no scarring is left.
The condition mostly affects adolescents and young adults around 10-29 years, peaking between 20-29. Although the cause of pityriasis rosea is uncertain, several factors include epidemiological and infective agents. Microscopy findings suggest the implication of human herpesvirus 6 and 7. One study showed elevated levels of human herpesvirus 7 in patients with pityriasis rosea, however further studies were not consistent with results of the aforementioned study because the level of human herpesvirus in affected patients was not significantly different from the controls.
Pharmaceutical drugs like certain antibiotics, antidepressants, antiepileptics and a myriad of other medications have been attributed to the onset of pityriasis rosea. The drugs induced pityriasis rosea violet-red in color in lieu of the typical herald patch.
Diagnosis of the condition is elusive, especially during the onset. It can be misconstrued with other viral exanthems and copious differential diagnoses. So far there are no non-invasive tests for diagnosis but clinical features are imperative in diagnosing the condition. Discrete, large oval lesions, i.e herald patch, with peripheral collarette scaling appear typically on the truncal region. African Americans have more severe symptoms and complications.
Treatment of pityriasis rosea is highly contentious. On the basis of a few controlled trial studies, erythromycin and macrolides have shown promising results but are still inconclusive, therefore they should not be adopted in clinical routine studies until further studies are conducted. The important objective is to relieve symptoms such as pruritus with zinc oxide, oral antihistamine, and topical corticosteroids. For the most part, pityriasis rosea is a self-limiting condition that does not require intervention and will resolve within eight weeks.
Written by: Naif Alalsheikh, medical student