CHAPTER XL 

 FAVUS 



AcHORiON SchOnleinii (Remak) 



Favus, or tinea favosa, is a chronic and destructive form of 

 dermatomycosis occurring in man and animals, caused by a fungus 

 discovered in 1839 by Schonlein,* and called in his honor Achorion 

 schonleinii by Remak in 1845. This fungus is widely distributed 

 and affects mice, cats, dogs, rabbits, fowls, and men. Among 

 human beings it usually occurs upon the scalp and other hairy parts 

 of the body, though it may also affect the hairless portions and even ' 

 attack the roots of the nails. It is more frequent in children than 

 in adults. The fungus grows vigorously and usually forms a small 

 sulphur yellow disk about the base of a hair. The edges of this 

 detach, become everted, and the whole eventually separates, forming 

 the "scutulum," or characteristic lesion of the disease. The reac- 

 tion is more marked, the damage done greater, and the disease less 

 tractable than in other forms of dermatomycosis. 



The infection seems to take place in most cases by way of the hair- 

 follicles, and the mycelia of the fungi grow into and about the hairs, 

 invading the epiderm, and causing atrophy of the hair-follicles by 

 pressure. Beneath and around the scutulum, which consists chiefly 

 of the fungi, an inflammatory reaction takes place, and leukocytic 

 invasion and ulceration cause the scutulum to separate. 



Although usually confined to the skin, the favus infection may ex- 

 tend to the mucous membranes, and Kaposi and Kundratf have 

 reported a case in which fuvas fungi were found to have invaded 

 the stomach and intestines. 



The disease runs a course sometimes extending over many years. 

 Crocker J mentions a case that recovered after thirteen years. It 

 may remain localized upon the scalp or may spread itself over much 

 of the skin surface. When the lesions are large they give off an 

 odor suggesting that peculiar to white mice. In recovering, the 

 lesions leave considerable cicatricial scarring, and atrophy of hair- 

 follicles, sweat, and sebaceous glands is inevitable. 



The Specific Organism. — The Achorion schonleinii is probably 

 better regarded as a group of closely related organisms than as a 

 single one. Quincke has described three species, though they are 

 not yet generally accepted. 



*Muller's "Archiv," 1839. 



t"Ann. de Dermat. et de Syph.," 1895, p. 104. 

 i "Diseases of the Skin," Phila., 1903, p. 1276. 

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