126 An Introduction to Medical Mycology 



changes in the substance of the nail is usually due to M. albicans. In the 

 invasive type of filamentous infection, the cardinal symptoms of yellowness, 

 friability and opacity of the nail and the negative sign of lack of paronychia 

 will usually point to the correct diagnosis. The white specks or patches fre- 

 quently seen on the edges of toenails are due to the presence of T. gypseum. 



(5) Dermatophytid-like eruptions.— Toxic eruptions simulating derma- 

 tophytid may result from sensitivity to certain drugs. The absence of signs 

 of a focus of tinea, the lack of an inflammatory focus on the feet and the 

 history of ingestion of a drug point to the correct diagnosis. When a vesicu- 

 lar eruption is present on the hands, particularly on the fingers and palms, 

 the diagnosis of dermatophytid is commonly given even without corrobora- 

 tion. In the majority of cases, however, such a condition is not of fungous 

 origin. The criteria for the diagnosis of dermatophytid have already been 

 detailed; it is at least necessary to find an active fungous focus and to ob- 

 serve a positive reaction to the trichophytin test. The diagnosis of dyshi- 

 drosis or pompholyx is made by excluding dermatophytid and dermatitis 

 venenata. The former disorder has been discussed; in diagnosing the latter, 

 one is helped by the absence of an active fungous focus and of a reaction to 

 trichophytin, but their presence does not exclude the condition. An accurate 

 history of contact with a possible sensitizing agent, particularly if the initial 

 exposure was fairly recent, may point to the correct diagnosis. When sec- 

 ondary eczematous changes result from trauma or misdirected therapy, an 

 additional factor or factors may make a definite diagnosis impossible. At 

 present, unfortunately, a large number of patients with such lesions present 

 themselves for treatment; they constitute a rather unsatisfactory group, in 

 regard to both accurate diagnosis and therapeutic results. We believe that 

 it is a mistake to classify all eczematous changes in the hands as derrna- 

 tophytids. Another disorder previously mentioned, namely, pustular psori- 

 asis, shows groups of deep-seated pustules. The sides of the fingers are 

 rarely involved, the lesions are not evanescent, and response to therapy is 

 poor. 



(i) Prognosis.— This varies for involvement both of the skin and of the 

 nails according to the infecting micro-organism, the allergic response in the 

 patient, the factors predisposing to the infection and the duration and 

 extent of the involvement. When T. gypseum is the causative fungus, the 

 prognosis is hopeful. The infection may be severe, but cure may be expected. 

 If T. purpureum is the offending micro-organism, cure is difficult and will 

 probably take several months or even years. A vigorous reaction to the 

 trichophytin test is a hopeful sign. As For the factors which predispose 

 toward the disease, hyperhidrosis, unless it is controlled, may hinder a 

 rapid response to therapy. If an underlying factor of ill health is uncor- 



