62 An Introduction to Medical Mycology 



instances horny spikes, or spines, capped the lesions, when the appearance 

 was similar to that of lichen spinulosus. The work of Jadassohn, Bloch, 

 Gnth and others of their school soon showed that these rashes ( and others 

 resembling erythema toxicum, erythema multiforme or the like) were ex- 

 pressions of cutaneous allergy due to a hematogenous spread from an in- 

 flammatory focus on the scalp. We designate a rash of this character as 

 dermatophytid. Fungi or their products caused sensitization of the skin, 

 and this altered reaction resulted in lesions which in themselves were 

 sterile. We have observed a number of instances of dermatophytid in 

 children with tinea capitis in which the appearance of the rash coincided 

 with or followed a depilating dose of roentgen rays. We studied a rash 

 on a child who received trichophytin therapeutically. In all instances the 

 patient exhibited a strong reaction to the intracutaneous test with tricho- 

 phytin. The origin of the rash was always an inflammatory lesion or lesions, 

 most frequently being frank kerion. Sometimes strong topical applica- 

 tions causing marked inflammatory changes have resulted in dermatophytid. 

 The subject is further discussed in the section on dermatophytosis, pp. 

 116 ff. 



(d) Reaction to trichophytin.— Patients with ringworm of the scalp 

 vary in their reaction to trichophytin, mainly in accordance with the type 

 of infecting micro-organism. There is usually more response when the 

 fungus is also pathogenic to animals. The reaction may be valuable in 

 helping the physician to determine the type of therapy. In infections due 

 to M. audouini the response to the intracutaneous test with trichophytin 

 is usually slight. With endothrix infections, such as those due to A. schoen- 

 leini and T. violaceum, the reaction to the test is commonly negative or 

 only slightly positive. When tinea of the scalp is caused by M. lanosum, 

 M. fulvum, T. crateriforme or T. gypseum, a moderate or marked reaction 

 to trichophytin is the rule. 



(e) Filtered ultraviolet rays.— The nature and use of these rays has 

 been mentioned elsewhere. Since under the rays a suspected scalp will show 

 a characteristic fluorescent effect whenever infected hair is present (except 

 in the rare instances of ectothrix infection), it is apparent that the use of 

 ultraviolet rays is important in revealing not only the presence but the 

 extent of the infection. One is frequently surprised to find widespread 

 involvement when clinical inspection has led one to believe that only one 

 or two areas of infection were present. Furthermore, we have observed 

 several patients in whom regrowth of hair in patches of partial alopecia due 

 to a tinea infection was sufficiently vigorous to mask the disease. Numerous 

 infected hairs were observed by the test of fluorescence. 



Hairs infected with one of the commonly found Microspora (M. lanosum, 



