Onychomycosis (Tinea Unguium) By Chris G Adigun, MD, Dermatology & Laser Center of Chapel Hill Reviewed / Revised Dec 2021 | Modified Sep 2022 View Patient Education Symptoms and Signs Diagnosis Treatment Key Points More Information Topic Resources Onychomycosis Onychomycosis of the Great... Onychomycosis is fungal infection of the nail plate, nail bed, or both.