Skin Skin Lesions And Disorders Of Pigmentation fb6d00cb Twelve-year-old boy with vesicle over lip. Investigation to be done is: A KOH mount B Tzank smear C Diascopy D Woods lamp High-Yield Explanation Ans. b. Tzanck smearHerpes labialis occurs due to HSV-I injection on Tzanck smear shows, multinucleated giant cells (MNGC).