440 MEDICAL MYCOLOGY 



may occur. The formation of vesicles is rare, but the thickened layer loosens 

 and peels, giving the syndrome of dysidrosis lamellosa sicca. Fungi are rather 

 difficult to isolate in these cases. Sabouraud reports Trichophyton tonsurans 

 from similar lesions on his own hands (probably accidental infection) and T. 

 persicolor. He also reports Favotrichophyton violaceum (Trichophyton viola- 

 ceum) causing lesions of the dysidrotie type. Gonzales Uruena (1930) re- 

 ported Ectotrichophyton jnentagrophytes var. from a Mexican case, while 

 Photinos (1928) reported Favortrichophyton ochraceum. 



In the interior of Java and Borneo, perhaps also in Sumatra and New 

 Guinea, a somewhat similar condition is caused by Aleurisma alhiciscans 

 (Trichophyton alhiciscans). The systematic position of this fungus is uncer- 

 tain, as we know nothing of its cytology (see p. 788). 



In tinea unguium, when Trichophyton attacks the nails, it may be by 

 direct infection or by infection from a neighboring lesion of the epidermis. 

 It begins on the lateral border of the nail as an opaque, extensive yellowish 

 white spot with irregular margins below the external layer. From this stage 

 it may develop in two ways, depending on whether the external layer is in- 

 volved or not. If this layer is not involved, it covers a thick, spongy layer 

 3-5 times its ordinary thickness, whose substance at the free edge is friable. 

 The surface of the nail is often concave and petaloid, sometimes with longi- 

 tudinal fissures, opaque, gray-white, or slightly yellowish. In other cases, the 

 spongy mass is so friable that it is easily dissociated and removed, the upper 

 layer covering an empty space over the upper half of the nail. In these cases 

 the nail becomes convex in two directions, producing onychogryposis. Finally, 

 the upper layer may be destroyed. In the second type, where the upper sur- 

 face is early attacked, it is fissured, soon becomes soft, and wears away. It 

 is then atrophic and reduced to half its normal length. The roughened surface 

 soon accumulates dust and dirt. Usually this process proceeds without in- 

 flammation. Gradually other nails become infected until sometimes all are 

 attacked. Microscopic examination shows little difference from that of nails 

 attacked by favus (see p. 443). The disease may last 10 years or more; very 

 rarely a nail recovers spontaneously. The organism has been cultivated in 

 comparatively few cases, but Sabouraud reports both T. Sahouraudi (T. acumi- 

 natum) and Favotrichophyton violaceum (T. violaceum) as causal agents, 

 Bresciani (1925) a case due to Microsporum Auclouini, Chalmers & Marshall 

 (1918) one due to Epidermophyton floccosum ? (E. inguinale) ^ Heller (1923) 

 lists M. Audouini, T. Sahouraudi (T. acuminatum), F. violaceum, T. flavum 

 (T. cerelriforme) T. plicatile, T. tonsurans (T. crateriforme). Hodges (1921) 

 adds Epidermophyton ruhrum {Trichophyton A, B), and E. hit er dig it ale {Tri- 

 chophyton C) . 



Of the various lesions associated with the hair follicle and hair, the first 

 to be differentiated clinically, and the most distinct, is that of favus. The 

 favic scutulum (godet of French writers) is a yellow crust resembling a 

 lupine seed which gave the disease some of its older names, such as porrigo 



