The spleen (and occasionally the liver) is frequently large, congested, and friable, and studded with infarctions to a greater or less extent.
The kidneys are either simply congested or the seat of nephritis or infarctions. The same forms of inflammation which accompany scarlatina—to wit, the desquamative and the diffuse—are here observed. The diffuse form is not of so frequent occurrence as in scarlatina, but is sometimes extensive and dangerous.
The muscles occasionally exhibit ecchymoses, and are at times the seat of parenchymatous inflammation, gray degeneration, and atrophy.
The lymphatic glands are frequently inflamed and swollen, either hard or doughy, oedematous or congested. Large abscesses are rare. It is more especially the gland tissue, and less the connective tissue of the glands, which takes part in the pathological process. The periglandular tissue very soon becomes involved, however. Necrotic foci have been described by Bizzozero. When the entire surface of the mucous membrane of the mouth and of the air-passages, from the nose to the trachea, is the seat of the disease, there is an impregnation of the mucous membrane, from the epithelial surface to the submucous tissue, of the entire tongue, borders of the lips, and frequently of the lips and cheeks, as well as of the tonsils, the lower portion of the nasal cavities and the upper, and especially the anterior, portion of the larynx. The fossæ Morgagni and the posterior aspect of the soft palate are more frequently affected in the same way than the anterior aspect. Small isolated spots are found on the tonsils and occasionally on the posterior wall of the pharynx. The so-called croupous form—that is to say, the one in which the membranes deposited may either be removed in large patches or lie macerated in the profuse secretion of subjacent mucous glands—is found partly in the nasal cavities, on the posterior surface of the soft palate, and also in the trachea and its subdivisions.
The character of the mucous membrane varies with the locality. Its different elements, as the epithelium, the basement membrane, the connective tissue mingled with elastic fibres, the blood-vessels, the nerves from the cerebro-spinal and sympathetic systems, and the papillæ and ducts of numberless glands, all influence the pathological process going on upon the surface. Their distribution in the oral cavity and the respiratory organs is a very interesting study, and in a table already published,37 I have exhibited it in a condensed tabular form.
37 Treatise on Diphtheria, p. 126.
Where elastic tissue predominates, diphtheritic impregnation is slow to take place, and recovery is also slow when the tissue has finally submitted. Pavement epithelium yields the easiest foothold to diphtheritic membrane. Thus it is that the tonsils, not from their prominent situation alone, favor the reception and development of the infection. But the elastic and connective fibres when once affected are apt to harbor the disease a long time. Still, there is another reason why the diphtheritic process should favor the tonsils. For Th. Höhr has demonstrated that their epithelium exhibits interruptions in its continuity. Through them round cells may emigrate. Wherever the epithelial covering of the integuments (skin or mucous membrane) is intact and unbroken, diphtheria takes hold with difficulty. But where a defect is established, large or small, diphtheritic formations will be apt to take place according to the size of the abrasion. This is one of the modes of the formation of small diphtheritic deposits on the tonsils, which it has been the tendency of many, both practitioners and authors, to honor with special names.
Ciliated epithelium is not so liable to be affected. It occupies a higher rank in the scale of animal formations, has a more complex function and a greater power of resistance. The presence of a large number of mucous glands impedes, as a rule, by the presence of the normal secretion, an extensive destructive action upon the tissues. The secreted mucus assists in removing epithelial masses, and even fibrinous exudations, from the surface. Thus it is that the deposits in the respiratory portion of the nasal cavities are frequently cast off through the nostrils, and in a similar manner the membranes that have formed in the trachea are ejected in a semi-solid condition through the opening made by tracheotomy. The large number of mucous glands in the larynx and trachea is unquestionably the reason why the lymphatic vessels of the mucous membrane are not influenced by the overlying loosened masses, and will not absorb; hence laryngeal and tracheal diphtheria, when not complicated, have decidedly a local character, and are usually devoid of constitutional symptoms. For the same reason the usual form of tonsillar diphtheria is a mild disease. On the other hand, the large number and size of the lymphatic ducts of the Schneiderian mucous membrane, as well as their direct communication with the lymphatic glands of the neck, accounts for the dangerous character of nasal diphtheria.
Diphtheria of the intestinal canal is characterized by fibrinous deposits on the surface and in the tissues of the intestine, with subsequent granular degeneration. It is mostly preceded by a catarrhal process. The same condition is found in the urinary organs.
There are but few autopsies of cases which have died of, or during, diphtheritic paralysis. In some instances there was considerable thickening of the spinal nerves at the junction of the posterior and anterior roots, with hemorrhages. The superficial connective tissue in these places exhibited a diphtheritic exudation (Buhl). There was in the sheath of the nerves of the cerebral and spinal meninges and in the gray substance of the cord voluminous nuclear infiltration; in one case there were extensive hemorrhages in the spinal meninges, with nuclear proliferation in the gray substance of the cord (Oertel). Disseminated meningitis with perineuritis of the neighboring roots, characterized by infiltration of nuclei between the nerve-fibrillæ was found by Pierret; and degeneration of the palatine nerves and fatty degeneration of the palatine muscles by Charcot and Vulpian. Dejerine, in five autopsies, records an atrophy of the anterior roots secondary to a myelitic degeneration of the ganglia of the anterior horns. E. Gaucher found the same in the case of a boy who died with paralysis of the muscles of deglutition, of the extremities, and of the trunk. In a child of two years with paralysis of the palate and extremities the autopsy was negative. In two cases Dejerine reports finding changes in the intramuscular nerves, such as liquefaction of myelin and loss of axis cylinders.