[Tinea unguium].

Although onychomycoses are caused by dermatophytes, yeasts or non-dermatophyte molds, tinea unguium describes chronic fungal infections by dermatophytes only. Tinea unguium is a common fungal infection of the nail plate or nail bed with increasing prevalence worldwide. It is not self-limited and shows a higher frequency among the elderly population. In Japan, approximately 10% of the entire population is estimated to have tinea unguium. During the period when only griseofulvin was available for treatment, it was a very difficult disease to treat. Since in the 1990's, however, the introduction of new oral antifungals, itraconazole and terbinafine, initiated a new era in the treatment of tinea unguium. Many excellent textbooks, review articles, and original articles have already been published. This paper considers the circumstances in Japan, epidemiology, causative agents including non-dermatophyte molds, differential diagnosis, diagnostic techniques, the quality of life of the patients with tinea unguium, and then the treatment options are reviewed again.