A 70 year old farmer ,presented to you with complaints of yellowish discolouration of his finger nails for the past 6 months, he also gives history of recurrent episodes of itiching in the groin for which he used to take local home made herbal remedy. On examination 3 of his toe nails also show similar change with tunneling. Which among the following is the best test for rapid confirmation of your diagnosis?

Patient is showing features of Tinea unguium i.e trichophyton infection of fingernails or toenails. It is most commonly caused by T rubrum. In this case KOH mount of nail clippings is helpful for rapid diagnosis as KOH will lyse the keratinous tissue and the fungal hyphae is easily visualised. In case of fungal infection of finger nails oral griseofulvin is given for 4 to 6months and 8 to 12 months in case of an infection of toe nails.