TINEA NIGRA 



2079 



slow, and takes place at the bottom of the tubes, with formation of a black 

 or greenish-black sediment. 



The optimum temperature for the growth of the fungus is betwen 30° and 

 32° C; above 35° C. and under 25° C. the growth is much slower, and may be 

 nil under 20° C. Further details on the fungus may be found on p. iioo. 



Symptomatology. — The affected parts are of a black, dull, lustre- 

 less colour, much darker than the surrounding dark, healthy skin 

 of the native. The patches may be small, roundish, and separated 

 from one another, or may coalesce; the patches are often slightly 

 elevated, and may present a slight desquamation. Little, if any, 

 pruritus is present. The face is not usually affected, though the 

 eruption may be found on practically any other region of the body. 

 The neck and upper portion of the chest are apparently the regions 

 most frequently affected. Tinea nigra usually attacks natives. 

 We have, however, 



seen it also in one of 

 our European patients, 

 who went for a pleasure 

 trip to Burma, where 

 he remained about a 

 month. On coming 

 back to Ceylon, he 

 noticed a small, 

 roundish, very slightly 

 elevated, non-desqua- 

 •mating, black patch 

 on the palm of his left 

 hand. There was no 

 pruritus. The patch 

 spread slowly for two 

 months, reaching the 

 size of a sixpenny- 

 piece. It disappeared 

 after a single applica- 



tion of formalin ; three Fig. 827. — Fungus of Tinea Nigra. 



months later it re- 

 appeared in the same place as a tiny black dot, which slowly 

 spread. Another application of formalin caused it to again dis- 

 appear. From the patch a fungus was grown identical with the one 

 found in native cases. 



Mixed Infections. — A mixed infection of tinea nigra and tinea 

 flava is somewhat frequently met with. Several of our patients 

 had on the neck a few round patches of tinea nigra, and on the 

 face some smooth, yellow, roundish patches of tinea flava. 



Diagnosis. — The characters of the fungus, and the fact that the 

 disease is easily curable, readily distinguish tinea nigra from 

 pinta. Pityriasis versicolor is generally of lighter colour than tinea 

 nigra, and the fungus [Malassezia versicolor) is morphologically very 

 different, and cannot be grown. In chloasma bronzinum no fungus 

 is found. 



