162 An Introduction to Medical Mycology 



mented skin. A mechanical cause was indicated by the facts that ( 1 ) the 

 dopa reaction revealed a normal amount of pigment in the skin; (2) the 

 scales of tinea versicolor protected the skin from ultraviolet rays to a 

 greater degree than the scales of psoriasis or of pityriasis rosea; (3) fluo- 

 rescent material from cultures of other fungi possessed a screening effect 

 against ultraviolet radiation, and (4) increase in pigment in a patch was 

 possible only when the overlying micro-organism had previously been 

 treated and destroyed. 



(c) Immune reaction.— There is no acquired sensitivity to trichophytin. 

 Since the cultivation of M. furfur is still a matter of conjecture, specific 

 sensitization to a vaccine remains to be proved. Since the process is super- 

 ficial and no involvement of the cutis is to be observed, sensitization is 

 unlikely. 



(d) Differential diagnosis.— The ordinary form of tinea versicolor can 

 hardly be confused with any other disease. If of limited extent, it may simu- 

 late chloasma. Since the organism can be readily demonstrated and since 

 the appearance under the filtered ultraviolet rays is characteristic, there 

 should be no mistake. 



With pseudo-achromia of tinea versicolor, however, certain other diseases 

 may be considered. 



(1) Achromie parasitaire a recrudescence estivale— From the published 

 description of Jeanselme it appears that this disease is pseudo-achromia of 

 tinea versicolor. 



(2) Achromia parasitaria.— It is difficult to fit together the varied symp- 

 toms in the syndrome which Pardo-Castello and Dominguez described. In 

 some cases irregular, dirty-white macules and patches which are slightly 

 inflamed, scaly and somewhat itchy are present on the face and neck. 

 In other cases the eruption is generalized, no inflammatory symptoms are 

 present, and the disorder simulates the pseudo-achromia of tinea versicolor. 

 In one of the illustrations in the article by Pardo-Castello and Dominguez 

 are shown lesions on the trunk which suggest the last-mentioned disease. 

 In both disorders, the scaling in the early macules is white and furfuraceous 

 and the older lesions are devoid of scales. There is no increase of pigment 

 at the edges. The mucous membranes, hair and nails are not affected. In 

 the series reported by Pardo-Castello and Dominguez there were four 

 cases in which the disorder was generalized, the palms and soles being 

 free. Aspergillus was cultured in six of 36 cases and was considered a pos- 

 sible cause of the disease. No mention was made of examination of scales 

 in potassium hydroxide for the presence of M. furfur. In a later communi- 

 cation, Pardo-Castello expressed his belief that the same clinical picture 

 may be found in patients of different races and in persons residing in differ- 



