308 An Introduction to Medical Mycology 



(h) Differential diagnosis.— The main species of fungus to be differ- 

 entiated is T. gypseum. The cultural growth of T. purpureum is typical 

 when starting and developing, and the tinctorial changes are characteristic. 

 ( See also the preceding section on T. gypseum. ) 



BIBLIOGRAPHY 



Lewis, G. M., and Hopper, M. E.: Cultural variations of Trichophyton purpureum (Bang) 

 with discussion of recognizable features, Arch. Dermat. & Syph. 41:895, 1940. 



12. EPIDERMOPHYTON INGUINALE (EPIDERMOPHYTON 

 CRURIS; EPIDERMOPHYTON FLOCCOSUM) 



This organism is found sporadically in various parts of the world. It is 

 capable of producing epidemics in institutions, in camps, on ships and 

 elsewhere. It is said to be more common in the tropics and is known in 

 India as the organism which causes dhobie itch. 



(a) Clinical characteristics.— This species of fungus has never been 

 found as a follicular invader. The classic location for the eruption is the 

 upper inner surfaces of the thighs, but the axillae, the interdigital webs 

 and other parts of the feet and other areas of the smooth skin may be 

 affected. In two instances we have isolated this fungus from scaly lesions 

 on the hands. Usually the affected skin is not primarily severely inflamed, 

 and macroscopic vesiculation is rarely noted. The affected skin is sharply 

 marginated and red, with little tendency to central clearing. The surface 

 is scaly, and sometimes the scaling is so abundant that only slight erythema 

 is observed. Small satellite lesions are characteristic. There may be macer- 

 ation on the webs of the toes; less frequently, vesicopustules may be found 

 on the soles. Tinea unguium is rarely if ever caused by this organism. 



(b) Immunologic reactions.— There are seldom strong reactions to tri- 

 chophytin. Reactions are moderate or, more commonly, mild or even 

 negative. 



(c) Microscopic features.— Chains of spores in which the elements tend 

 to be flattened are frequently noted in fairly large numbers. When the 

 scaling is profuse, large amounts of fungous material will be observed. 



(d) Cultural characteristics.— Growth begins slowly and may not 

 be apparent for two or three weeks. It then continues at a moderate rate. 

 The colony has a velvety or felted surface with irregular folds and grooves; 

 at times the surface max be smooth. The aerial hyphae are few. The color 

 is characteristically grayish olive-drab but sometimes is greenish drab. 

 Pleomorphic growth, as evidenced by whitish tufts, is common, appears 

 early and may eventually cover the entire agar slant. 



