<prompt> A 25 year old male presents with multiple erythematous annular plaques with peripheral collarette of scales arranged predominantly over trunk. What is the most probable diagnosis?Pityriasis versicolorPityriasis rubra pilarisPityriasis roseaPityriasis lichenoides chonica  <response>: Pityriasis Rosea is a self limiting papulosquamous dermatoses of unknown aetiology characterised by Herald patch, annular plaque with peripheral collarette of scales on the trunk and secondary lesions arranged in Christmas treefir tree appearance. Treatment is usually symptomatic. It resolves in about 8-10 weeks. Ref: Illustrated Synopsis of Dermatology and STDs By Neena Khanna, Pages 50-51 