76 An Introduction to Medical Mycology 



(a) Etiology.— In the majority of cases the condition is due to T. gyp- 

 seum. In a scattering of cases it is caused by M. lanosum, Trichophyton 

 rosaceum, T. violaceum and T. purpureum. It is chiefly men who are vul- 

 nerable, and in many instances the barber shop has apparently been respon- 

 sible for passing along the infection. Animals also play a part as carriers 

 of T. gypseum or M. lanosum. In some instances the infection is caught 

 from another person, not uncommonly a child with infection of the scalp 

 or of the glabrous skin. 



( b ) Symptomatology.— There are two types of infection, with dissimilar 

 clinical pictures. 



(1) Kerion type— -There is usually a history of contact with a diseased 

 animal. When the infecting organism is T. gypseum or M. lanosum, the 

 response is usually the development of one or more boggy infiltrations, par- 

 ticularly around the angle of the jaw. Any part of the beard may become 

 infected, but the upper lip is an unusual site. The resemblance to kerion, 

 as noted with ringworm of the scalp, is frequently striking. Hairs in the 

 affected tissue loosen and either come out spontaneously or are readily 

 extracted. 



(2) Sycosis type.— When T. violaceum or T. purpureum causes tinea 

 barbae, the infection gradually spreads, resulting in a mild pustular 

 (crusted) folliculitis with breaking off of the invaded hair (T. violaceum) 

 or similarly without the formation of hair stumps (T. purpureum). 



(c) Reaction to trichophytin.— Here, as with the other types of super- 

 ficial fungous infection, the result of the intracutaneous test with trichophy- 

 tin is dependent on the type of infecting micro-organism. If T. gypseum 

 or M. lanosum is the causal fungus, there is usually a vigorous reaction; if 

 T. purpureum or T. violaceum is responsible for the infection, negative or 

 slightly positive reactions may be expected. 



(d) Filtered ultraviolet rays.— If M. lanosum or T. violaceum is pres- 

 ent, fluorescence of the infected hair under these rays may be noticed. 

 Since both T. gypseum and T. purpureum are eetothrix organisms, no fluor- 

 escence will be observed when they are present. 



( e ) Differential diagnosis.— The kerion type of tinea barbae has to be 

 differentiated from sycosis barbae, iododerma or bromoderma and syphilis. 

 In sycosis barbae the lesions are rarely kerionic, the upper lip is fre- 

 quently affected, and the hairs in the affected follicles are epilated with 

 difficulty. Pustular reactions to one of the halogens is determined by the 

 history, the tendency to bilateral involvement, the presence of the disorder 

 elsewhere on the body and detection of the substance in the urine. Pustular 

 syphilis is rare, doubly so if confined to the beard alone. 



In all cases of tinea barbae the demonstration of the causal micro- 



