This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Erythmato-Squamous and Lichenoid Eruption, Subject name: Skin
[{'content': "Koebner's phenomenon is not seen in: \nSelect and explain. \nA. Vitiligo, B. Psoriasis, C. Dermatitis herpertiformis, D. Lichen planus", 'role': 'user'}, {'content': 'Answer: C \nExplanation: Ref: Thappa DM. The isomorphic phenomenon of Koebner. Indian J Dermatol Venereal Leprol 2004;70:187-9.Explanation:The Koebner phenomenon is the development of isomorphic pathologic lesions in the traumatized uninvolved skin of patients who have cutaneous diseases.Koebner phenomenon signifies activity of the disease.Types of Koebner phenomenon:1. True isomorphic phenomenon:There appear to be three disease processes that display the true isomorphic response of Koebner:PsoriasisLichen planusVitiligo.2. Pseudoisomorphic phenomenon:The Koebner phenomenon also seen in infectious diseasesWartsMolluscum contagiosumBehcet\'s diseasePyoderma gangrenosum.3. Occasionally occurring isomorphic phenomenon:In this category, diseases occasionally localize to sites of trauma, e.g.Cancer (gastric, testicular or mammary )Darier\'s diseaseErythema multiformeHailey-Hailey diseaseKaposi\'s sarcomaKyrle\'s diseaseLichen sclerosus et atrophieusPellagraPerforating folliculitisReactive perforating collagenosis.Koebner response in psoriasis:The reported incidence of Koebner response in psoriasis varies from 11-75%.The latent period between injury to uninvolved skin and appearance of disease is usually 10-14 days, but it may range from 3 days to several years.The "reverse" Koebner response:The reverse Koebner reaction is seen when an area of psoriasis clears following injury.', 'role': 'assistant'}]