a) polymorphic light eruption _ _ _ _ _ _ _ _ _ _ Wrong answer ¯ ¯ ¯ ¯ ¯ ¯ ¯ ¯ ¯ ¯ b) photoallergic contact dermatitis _ _ _ _ _ _ _ _ _ _ Wrong answer ¯ ¯ ¯ ¯ ¯ ¯ ¯ ¯ ¯ ¯ c) the Auspitz sign _ _ _ _ _ _ _ _ _ _ Wrong answer ¯ ¯ ¯ ¯ ¯ ¯ ¯ ¯ ¯ ¯ d) the Koebner phenomenon _ _ _ _ _ _ _ _ _ _ Correct ¯ ¯ ¯ ¯ ¯ ¯ ¯ ¯ ¯ ¯ e) vitiligo 2° to monobenzone in rubber _ _ _ _ _ _ _ _ _ _ Wrong answer ¯ ¯ ¯ ¯ ¯ ¯ ¯ ¯ ¯ ¯ Answer and Commentary _ _ _ _ _ _ _ _ _ _ The 19th century German dermatologist H. Koebner first described the induction of a lesion of an underlying disease following physical or non-specific trauma. This phenomenon is also known as the isomorphic effect and may be seen in a number of diseases including psoriasis, lichen planus and sarcoidosis. The Auspitz sign is elicited by lightly scratching off the psoriatic scales and producing bleeding. In psoriasis there is an irregular thickening of the epidermis but a thinning over the capillary containing dermal papillae. ¯ ¯ ¯ ¯ ¯ ¯ ¯ ¯ ¯ ¯
