94 An Introduction to Medical Mycology 



known. There have been epidemics, such as that reported by Mercer and 

 Farber. The localization is in part explained by the affinity of the fungus for 

 intertriginous areas. The crural region may also be the site of mycotic in- 

 fections due to T. gypseum and T. purpureum. 



(b) Immunologic reactions.— Epidermophyton inguinale usually does 

 not initiate sensitization to trichophytin. A test with trichophytin usually 

 elicits a negative or a mildly positive reaction. With T. gypseum, a positive 

 reaction is usual, but when T. purpureum is the causative fungus, a nega- 

 tive reaction is common. 



(c) Clinical data.— The rash is well marginated, the surface is scaly, 

 and the border shows minute vesicopustules. There is little or no tendency 

 to central clearing. The color of the lesions is brownish, with some redness 

 due to inflammation. The eruption is usually bilateral and symmetrical; 

 it favors the upper inner portions of the thighs but may extend up to the 

 pubis and as far back as the sacrum. The genitalia may share the infection. 

 According to Hopkins, the scrotum was commonly affected in patients he 

 studied at Fort Benning. The axillas, the umbilicus, the inframammary areas 

 and the interdigital webs of the feet are occasional sites of the infection. 

 Vesicopustules are sometimes seen on the soles. With the friction of cloth- 

 ing, especially during the heat of summer, varying degrees of secondary 

 eczematization occur. Follicular involvement is unknown. We have never 

 found E. inguinale in nail tissue. 



In cases of infection with T. gypseum, the feet are usually previously 

 involved, and inflammation is more marked, as evidenced by vesiculation 

 and exudative patches. The localization to the strictlv intertriginous parts 

 is more pronounced. With infections due to T. purpureum, dull red, scaly, 

 thickened plaques may be found in the crural region as part of a wide- 

 spread eruption. Itching is more marked than when the infection is due 

 to E. inguinale or to T. gypseum. The distribution is usually unilateral, in 

 contradistinction to the type caused by E. inguinale. 



(d) Differential diagnosis.— There i mix be some confusion with ery- 

 thrasma and moniliasis, particularly when areas other than the groins arc 

 affected. The red border of the former disorder and the moist character 

 ol the latter are distinguishing features. Psoriasis and seborrheic eczema 

 may also be simulated, but these diseases are rarely confined to this lo- 

 cation. 



(e) Prognosis.— The ordinary form of the disease usually responds read- 

 ily to medicinal applications. Relapse is common; it is probably due to 

 ill-timed stopping of the treatment or to reinfection from untreated parts 

 or from clothing. The lesions caused by T. gypseum arc likewise readily 

 cured, but those due to T. purpureum are extremely obstinate to all 



