A 24 year old man had multiple, small hypopigmented macules on the upper chest and back for the last three months. The macules were circular, arranged around follicles and many had coalesced to form large sheets. The surface of the macules showed fine scaling. e had similar lesions one year ago which subsided with treatment. The most appropriate investigation to confirm the diagnosis is –
Multiple small hypopigmented macules on chest & back, fine scales, history of perifollicular arrangment and reappearance after treatment suggert the diagnosis of P. versicolor. Examination of scales in 10% KOH shows short hyphae and round spores (sphagetti and meat ball appearance).
Potassium hydroxide preparation of scales
Slit skin smear from discrete macules
Tzanck test
Skin biopsy of coalesced macules