Itchy polygonal violaceous papules seen in -
Psoriasis
Pemphigus
Lichen planus
Pityriasis rosea
LICHEN PLANUS:- Inflammatory T cell mediated auto immune disorder affecting skin, hair,nails and mucous membranes.Four Ps- purple , polygonal and pruritic papule.Classic lesion- small polygonal shaped, and red/ violet, flat topped papule. Surface is slightly shiny/ transparent,and a network of fine,white lines called 'Wickhams striae' or small grey white puncta is also seen. Intense itching seen. Koebner phenomenon seen. IADVL textbook of dermatology, page 1070
Papulosquamous disorders