This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Papulosquamous disorders, Subject name: Dental
A male is presenting with a violaceous papule which is pruritic. There is pterygium of nail with cicatracial alopecia. Diagnosis is- 
Select and explain. 
A. Psoriasis, B. Pityriasis rosea, C. lichen planus, D. Seborrheic dermatitis
C: lichen planus
Answer: C: lichen planus 
Explanation: <p>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. violaceous pruritic papules, pterygium and cictricial alopecia are charecteristics of lichen planus IADVL textbook of dermatology, page 1070