55 De la Langue noire [Glossophytie], Paris, 1878, 8vo, p. 38, illustrated.
56 Gaz. Méd., Strasbourg, 1879.
57 Bull. Méd. du Nord, 1883.
58 Revue mensuelle de Laryngologie, etc., Sept., 1883, p. 276.
ETIOLOGY.—The affection appears to be due to some fault of nutrition, but the cause has not been determined. The fluids of the mouth always exhibit an acid reaction. It has been seen chiefly in dyspeptics and hypochondriacs, and has seemed in one instance (Moure) to have followed the use of chlorate-of-potash lozenges. A case has been recorded by Solomon Solis Cohen59 in a negro child the subject of congenital syphilis. Mr. George Stoker60 and G. Y. Broatch61 have each reported a case of long duration occurring in a painter.
59 The Polyclinic, Philada., July, 1884, p. 10.
60 Brit. Med. Journ., March 29, 1884, p. 602—said to be first case recorded in England.
61 Ibid., April 19, 1884.
PATHOLOGY AND MORBID ANATOMY.—The disease is characterized by a grayish-black or fully black discoloration on the upper surface of the tongue, which gives it an aspect which recalls the normal appearance of the tongue of the parrot and the giraffe, and an occasional appearance of the organ in the ox, sheep, dog, cat, and some other animals. The filiform papillæ are enormously elongated, so that they closely resemble hairs, and they are described by some writers as lying upon the surface of the tongue in confusion like that of a field of wheat thrown down by the wind. The individual papillæ are surrounded with a parasitic vegetable growth. Raynaud compared the microscopic spores in his case to the microphyte of tinea tonsurans or that of herpes circinatus. According to Malassez, they do not differ from those found in the saburral tongue of the dyspeptic, and he considers that their development is favored by their very arrest by the hypertrophied papillæ. Nevertheless, the subjects of this disease are not all dyspeptics by any means. Dessois made culture-efforts to reproduce the disease upon his own tongue, but failed to inoculate it. For detailed description of the disease we cannot do better than refer the interested reader to Dessois' monograph, from whose observations, chiefly, it appears that the discoloration begins at the central portion of the tongue, increases gradually in extent and intensity for three or four days, and then gradually disappears by desquamation. The tongue is very dry while the affection is at its height. Close examination of the parts and microscopic inspection of papillæ removed for the purpose are said to show that the spores of the cryptogam are first developed at the base of the papillæ, separating them from each other. The irritation produced by the parasite causes longitudinal hypertrophy of the papilla, and the continued growth of the parasite produces a muff-like envelopment of the papilla; the spores at the same time becoming insinuated between the most superficial epithelial cells and dislocating them, so that they maintain their position around the axis of the papilla only by means of the intervening parasitic masses. The papilla continues to elongate and the cryptogam to increase, until finally it invades nearly the entire length of the papilla. This entire parasitic mass soon becomes detached, carrying with it the epithelial cells under which it has become insinuated, and leaves the papilla naked, save for a few cells remaining attached by their superior borders. In the case observed by my brother, as in Mr. Stoker's and Broatch's cases, microscopical examination of the black filaments showed them to be composed of closely-packed epithelial cells, overlapping one another, stained brown, and decreasing in intensity of color from the apex toward the base of the filament. In some cells the nucleus was darker, and in others lighter, than the surrounding protoplasm. The cryptogam, therefore, cannot always be detected. Indeed, there seems reason to believe that the affection may not be parasitic,62 although the prominence given to this feature by French writers apparently warrants its being so considered. There may be two kinds of black tongue—one non-parasitic.
62 Hutchinson, The Medical Press, p. 20, July 11, 1883.