An Original Study on Blaschkoid Pityriasis Rosea – One of the Rarest Atypical Variants of this Paraviral Exanthema

Abstract

Background: Blaschko’s lines are believed to be originated from the migration of mosaic populations of epidermal cells and tissues. Pityriasis rosea (PR) is an exanthem which might be associated with human herpesvirus-7 and -6 infections. Objective: To evaluate the risk factors, clinical manifestations, co-morbid associations, and complications in patients with Blaschkoid PR, and to determine its relative incidence among all patients with PR. Methods: Our setting was a skin clinic served by a consultant dermatologist. We searched for and retrieved records of all patients with Blaschkoid PR presented to us during an eight-year period. Results: Out of 507 patients with PR seen by us, three (0.59%) patients had Blaschkoid PR. All three patients exhibited strictly unilateral distribution of one single group of lesions along Blaschko’s lines, as linear or slightly curved stripes. All three patients had prodromal symptoms, herald patches, secondary eruptions, peripheral collarette scaling for some lesions, and spontaneous clinical remission in two to six weeks.  We found no risk factor, co-morbidity, and no complications for patients with Blaschkoid PR. Conclusions: Blaschkoid PR is indeed rare. Apart from the rash distribution, clinical manifestations of this variant are in line with classical PR.