The test likely to help in diagnosis of a patient who presents with an itchy annular plaque on the face is –
The clinical picture is suggestive of a fungal infection most likely Tinea fascitis, KOH preparation is performed on scaling skin lesion when fungal etiology is suspected. Microscope examination after KOH digestion will show fungal hyphae.
Gram's stain
Potassium hydroxide mount
Tissue smear
Wood's lamp examination