KOH smear is helpful in diagnosis of
(C) Fungus # KOH Preparation> A Potassium Hydroxide (KOH) preparation is performed on scaling skin lesions where a fungal infection is suspected. The edge of such a lesion is scraped gently with a no. 15 scalpel blade, and the removed scale is collected on a glass microscope slide then treated with 1 to 2 drops of a solution of 10-20% KOH. KOH dissolves keratin and allows easier visualization of fungal elements. Brief heating of the slide accelerates dissolution of keratin.> When the preparation is viewed under the microscope, the refractile hyphae will be seen more easily when the light intensity is reduced and the condenser is lowered.> This technique can be used to identify hyphae in dermatophyte infections, pseudohyphae and budding yeast in Candida infections, and "spaghetti and meatballs" yeast forms in tinea versicolor. The same sampling technique can be used to obtain scale for culture of selected pathogenic organisms.
Bacteria
Virus
Fungus
Malignancy
Misc.