Background
Favus, also termed tinea favosa, is a chronic inflammatory dermatophytic infection usually caused by Trichophyton schoenleinii.[1, 2, 3] Rarely, favus is caused by Trichophyton violaceum, Trichophyton mentagrophytes var quinckeanum, or Microsporum gypseum. Favus typically affects scalp hair but also may infect glabrous skin and nails. The causative agent of mouse favus is T mentagrophytes var quinckeanum, also termed Trichophyton quinckeanum, which can cause favus in humans, although rarely.[4, 5]
Pathophysiology
Favus is a superficial dermatophyte infection usually caused by T schoenleinii. In most patients, favus is a severe form of tinea capitis; however, it may occur, although rarely, as onychomycosis, tinea barbae, or tinea corporis.
Favus is 1 of 3 primary patterns of hair infection (ectothrix, endothrix, favus). Typically, hair is not as heavily infected as in trichophytosis caused by Trichophyton tonsurans. Hair is able to grow, and frequently, long hairs are observed in the disease state. The most characteristic feature is the formation of air spaces between hyphae within the infected hair. These air spaces (air tunnels) form as a result of autolysis of the hyphae. Arthroconidia rarely are seen within the hair. Such infected hair commonly is termed favus-type hair. In the sera of patients, antibodies to causative fungi are found by charcoal agglutination and immunodiffusion assay; however, the exact role of antibodies is not clear.[6]
Epidemiology
Frequency
United States
Favus is uncommon in the United States, although foci have been described in past decades in rural areas of West Virginia, New York, Kentucky,[7] and Arkansas. Favus often is seen in geographic regions where lifestyles are associated with malnutrition, neglect, and poverty.
International
Foci of favus have been seen worldwide, including Poland,[8] Southern and Northern Africa,[9] Pakistan,[10] the United Kingdom, Australia, South America (Brazil),[11, 12] Canada (Quebec),[13, 14] and the Middle East.
Mortality/Morbidity
Permanent alopecia with scarring often follows favus, which is a chronic disfiguring infection.
Race
Favus shows no racial or ethnic preference.
Sex
Both females and males may be affected equally; however, some report a slight predominance of female patients with favus.
Age
Favus appears in both children and adults. Favus usually is acquired during childhood or adolescence and typically persists into adulthood.
Cecchi R, Paoli S, Giomi A, Rossetti R. Favus due to Trichophyton schoenleinii in a patient with metastatic bronchial carcinoma. Br J Dermatol. May 2003;148(5):1057. [Medline].
Khaled A, Ben Mbarek L, Kharfi M, et al. Tinea capitis favosa due to Trichophyton schoenleinii. Acta Dermatovenerol Alp Panonica Adriat. 2007;16:34-46.
Raszeja-Kotelba B, Adamski Z, Pawlowicz A. A case of tinea favosa capitis caused by Trichophyton schoenleinii. Przegl Dermatol. 1993;80:518-24.
Besbes M, Cheikhrouhou F, Sellami H, Makni F, Bouassida S, Ayadi A. Favus due to Trichophyton mentagrophytes var. quinckeanum. Mycoses. Sep 2003;46(8):358-60. [Medline].
Garcia-Sanchez MS, Pereiro M Jr, Pereiro MM, Toribio J. Favus due to Trichophyton mentagrophytes var. quinckeanum. Dermatology. 1997;194(2):177-9. [Medline].
Grappel SF, Blank F, Bishop CT. Circulating antibodies in human favus. Dermatologica. 1971;143(5):271-6. [Medline].
Loveman AB, Kotcher E. Favus in Kentucky: diagnosis, treatment and epidemiology. J Ky Med Assoc. Jul 1962;60:643-55. [Medline].
Pawlowicz A. Epidemiology of tinea capitis, particularly tinea favosa in the Poznan region. Postepy Dermatol (Poznan). 1996;13:347-400.
Scott DB, Scott FP. Dermatophytoses in South Africa. Sabouraudia. Nov 1973;11(3):279-82. [Medline].
Khan KA, Anwar AA. Study of 73 cases of tinea capitis and tinea favosa in adults and adolescents. J Invest Dermatol. Dec 1968;51(6):474-7. [Medline].
Matte SM, Lopes JO, Melo IS, Beber AA. A focus of favus due to Trichophyton schoenleinii in Rio Grande do Sul, Brasil. Rev Inst Med Trop Sao Paulo. Jan-Feb 1997;39(1):1-3. [Medline].
Prochnau A, de Almeida HL Jr, Souza PR, Vetoratto G, Duquia RP, Defferrari R. Scutular tinea of the scrotum: report of two cases. Mycoses. May 2005;48(3):162-4. [Medline].
BLANK F. Human favus in Quebec. Dermatologica. 1962;125:369-81. [Medline].
Joly J, Delage G, Auger P, Ricard P. Favus: twenty indigenous cases in the province of Quebec. Arch Dermatol. Nov 1978;114(11):1647-8. [Medline].
Ilkit M. Favus of the scalp: an overview and update. Mycopathologia. Sep 2010;170(3):143-54. [Medline].
García-Vargas A, Mayorga-Rodríguez JA, Sandoval-Tress C. Scalp demodicidosis mimicking favus in a 6-year-old boy. J Am Acad Dermato. 2007;57, suppl. 2:S19-S21.
Kwasniewska J. Current antifungal agents in dermatology. Postepy Dermatol (Poznan). 1997;14:129-35.
Baran E, Szepietowski J, Walow B. Fungal infections in the lower-Silesian region in the years 1974-1991. Part 1. Frequency of occurrence. Przegl Dermatol. 1992;79:294-301.
Ceburkovas O, Schwartz RA, Janniger CK. Tinea capitis: current concepts. J Dermatol. Mar 2000;27(3):144-8. [Medline].
Dvoretzky I, Fisher BK, Movshovitz M, Schewach-Millet M. Favus. Int J Dermatol. Mar 1980;19(2):89-92. [Medline].
Macura AB. Resistance to antimycotic drugs. Postepy Dermatol (Poznan). 1997;14:137-40.
Szepietowski J. Dermatomycoses and onychomycosis. A practical guide. Medycyna Praktyczna, Krakow. 2001.

