A 24 year old man presents with multiple small hypopigmented patches around hair follicles on upper chest and back. These macules were with fine scaling which coalesced later. He had received treatment 1 year back for the same type of lesion. Which of the following investigation should be done to diagnose this condition?
KOH preparation of scales Tzanck test Slit Skin Smear Skin biopsy of coalesced lesion