Tinea barbae is a superficial dermatophyte infection that is limited to the bearded areas of the face and neck and occurs almost exclusively in older adolescent and adult males. The clinical presentation of tinea barbae includes inflammatory, deep, kerionlike plaques and noninflammatory superficial patches resembling tinea corporis or bacterial folliculitis.
Tinea barbae is caused by the keratinophilic fungi (dermatophytes) that are responsible for most superficial fungal skin infections. They infect the stratum corneum of the epidermis, hair, and nails. Several enzymes, including keratinases, are released by dermatophytes, which help them invade the epidermis. The mechanism that causes tinea barbae is similar to that of tinea capitis. In both diseases, hair and hair follicles are invaded by fungi, producing an inflammatory response. Tinea barbae is caused by both zoophilic and anthropophilic dermatophytes.
Infection caused by zoophilic dermatophytes usually is of greater severity than that produced by anthropophilic organisms. Thus, zoophilic dermatophytes are the primary cause of inflammatory kerionlike plaques, which most likely result from a more intense host reaction. Kerion formation has been described as resulting from Trichophyton rubrum infection. [1, 2] T rubrum, an anthropophilic dermatophyte, can invade hair shafts and deeper tissues (although rarely), resulting in an inflammatory reaction. Usually, infection involving hair is more severe; therefore, tinea barbae caused by anthropophilic dermatophytes often has a more severe course than tinea corporis caused by the same pathogen.
Dermatomycoses may be due to pets and farm animals, sometimes from unusual dermatophytes. Trichophytonerinacei, a zoophilic dermatophyte occasionally harbored by hedgehogs, was linked with kerion-type tinea barbae in a 37-year-old man with the infection apparently transferred to his partner by direct contact from kissing.  Inflammatory tinea barbae was shown to be caused by Arthroderma benhamiae in both a patient and his guinea pig. 
The formation of kerion is postulated by 2 theories. The first theory suggests that it results from diffusion of metabolites and/or toxins from the fungus; however, kerion formation most likely results from an immunologic response to dermatophyte antigens.
Tinea barbae is uncommon in the United States.
Currently, tinea barbae is infrequent around the world. As with other dermatophytoses, tinea barbae is more common in countries in which weather is characterized by high temperatures and humidity. It represented only 5.8% of dermatophytosis in one survey from the tropical region of southern Iran. 
Tinea barbae was observed more frequently in the past before single-use razors became available, and infection frequently was transmitted by barbers who used unsanitary razors. Therefore, it is not surprising that tinea barbae once was termed barber's itch. Now that habits and equipment have changed, this source of infection has been all but eliminated. Currently, tinea barbae is more common among rural inhabitants, and zoophilic dermatophytes constitute its primary pathogens. Dermatophytosis from zoophilic species of dermatophytes has increased in southwestern Iran, with the Trichophyton species of A benhamiae being a new cause in southwestern Iran. 
Men are affected almost exclusively by tinea barbae because the disease involves the bearded areas of the face and neck. Involvement of the same areas in healthy women and children is classified as tinea faciei.
Hair appears on the face at puberty; therefore, tinea barbae may occur almost exclusively in older adolescent and adult males.
Prognosis usually is good for tinea barbae. Inflammatory lesions undergo spontaneous remission within a few months; however, if untreated, they leave scarring alopecia. Noninflammatory tinea barbae lesions are more likely to be chronic and may not tend to resolve spontaneously. In superficial chronic tinea barbae, alopecia may occur in the center of the lesions; however, this is not common.