EPIDERMOPHYTON 



175 



development of eczema-like lesions. The condition may yield to 

 treatment, but tends to recur, especially during the summer months. 

 Recurrence is probably more important in the incidence of infection 

 than reinfection. The sudden appearance of a lesion after unusual 

 amounts of walking or standing may be due merely to the sudden 

 activation of an old quiescent lesion in the epidermis or on a toe nail. 

 The presence of fungi has been demonstrated in skin showing no 

 evidence of clinical dermatophytosis or in skin at some distance from 

 an apparent lesion. The lesions in the nails are particularly difficult 

 to clear up completely and treatment is often stopped in the belief 

 that cure has been achieved when actually there is still a focus of 

 infection in a toe nail. 



A variety of fungi have been isolated. Although some of the cases 

 have been definitely associated with tinea cruris and Epidermoph- 

 yton jioccosum has been isolated from a considerable number of cases 

 (20 per cent in Mitchell's series), it is now apparent that the major- 

 ity of cases are caused by various varieties of Trichophyton menta- 

 grophytes {T. gypseum, T. inter digitale, T. pedis) and T. ruhrum. 



Epidermophyton. The genus Epidermophyton contains a single 

 species, Epidermophyton fioccosum {E. inguinale, E. cruris). The 



Fig. 87. Tinea cruris, due to Epidermophyton. 



