<prompt> Herald patch is seen in:Pityriasis roseaLichen planusPityriasis albaTaenia versicolour  <response>: Ans: a Pityriasis rosea Ref: Harrison, 16th ed p. 292; 17th ed, p. 317, Roxburghs Common skin ds, 17th ed, p. 17Herald patch is seen in pityriasis roseaPITYRIASIS ROSEAIt is an acute exanthematous papulosquamous eruption often with a characteristic self limiting course.Etiology is unknown, but 2 agents are suggested which include HHV-7 and legionella micadedi. Most commonly affects young adults FM Predominant involvement is limited to the trunkThe first feature is a single annular plaque usually on the trunk herald patch Principal lesions are oval or circular with long axis of oval lesion following lines of cleavage in a Christmas tree patternfir tree patternLesion may have fine scaling cigar paper scales 