Part 14

The latest contribution to the history and nature of this form of degeneration has been furnished by Vallat, from whose article many of the above data have been obtained.

Mucous Degeneration, Mucous Metamorphosis, Mucous Softening.

Of the various degenerations presenting a colloid--i.e. gelatinous--condition, the mucous variety is one of the most striking. Its gross appearances may not differ materially from those to be described under the head of colloid degeneration, but the diagnostic characteristic of the change is to be found in the presence of mucin. The presence of this substance is readily detected by the addition of acetic acid to mucus, the effect being a fibrillated appearance of the latter, the fibres presenting a more or less parallel distribution. This fibrillation of mucus is regarded as the result of a coagulation of its mucin, previously held in solution by an alkali. Mucin is thus present in the body as a normal constituent, and, in the secretions from mucous membranes, owes its origin to the existence of epithelial cells, whether these represent gland-cells, as in the case of the muciparous glands of the bronchial mucous membranes, or whether they are superficial cells, as those of the gastric and intestinal mucous membranes.

In the origin of mucus as a secretion from glands Heidenhain claims that a destruction of gland-cells accompanies the continuance of the secretion. At the outset, however, the mucin escapes from the cells, the latter remaining relatively intact. With the persistence of the secretion there results a destruction and a new formation of the muciparous cells. In the pathological production of mucus from mucous membranes, as in catarrh, there is no reason to doubt that the persistence of an irritation is the cause of abundant mucus, and that the latter is dependent upon the rapid formation and destruction of epithelial cells.

The origin of mucus from epithelial cells under physiological and pathological conditions being apparent, it readily follows that the epithelioid cells of tumors might be supposed to be liable to a similar metamorphosis. It is well known that cancerous tumors, especially those of the stomach and large intestine, are frequently met with, which present an abundant gelatinous material, more or less completely filling the spongy, fibrous meshwork. These are the alveolar, gelatinous, or colloid cancers.

The gelatinous or colloid material often gives the reaction of mucin, and the microscopic appearances of the tumor show that the jelly-like substance lies in that part of the tumor which corresponds with the position of the epithelioid cells. The latter are found in various stages of degeneration, the appearances being similar to those observed in the mucous degeneration of true epithelium.

The prevailing theory of the origin of cancer from epithelial structures {83} readily suggests an explanation for the frequency of the mucous variety of cancer in connection with those parts from which mucus normally arises from the degeneration of the epithelium.

The mucous metamorphosis affects connective tissues as well as epithelium. The Whartonian jelly of the umbilical cord and the vitreous humor of the eye are known, through the investigations of Virchow, to owe their gelatinous condition to the presence of mucin. The latter lies in the intercellular substance; that is, between the cells. The appearance of these indicates no degenerative process, but the presence of mucin is obviously an essential constituent of the tissue. Whether this mucin represents a transformation of the gelatin of the intercellular substance, or a secretion from the fixed cells, or a metamorphosis of the migratory cells of the tissue, is not known. In mucous tissue, however, there is present mucin, wholly independent of any epithelial degeneration. Mucous tissue is present in the eye as a normal constituent of the adult, and in the umbilical cord as a normal constituent of the infant at full term. It is also abundantly met with in the subcutaneous and intermuscular tissues of the foetus. Its pathological occurrence in the adult as a circumscribed tumor, the myxoma, may also be mentioned.

A gelatinous substance containing mucin is found in the adult independent of the mucous tissue, but obviously arising from a transformation of intercellular substance. The most striking example of this occurrence is the cystoid softening of cartilage, especially of the costal cartilages of old people, the basis substance being transformed into a fluid containing mucin. A similar metamorphosis is of frequent occurrence in the intervertebral disks and in the destruction of cartilage in acute and chronic inflammations of the joints. The intercellular substance of cartilaginous tumors also becomes softened and converted into a liquid containing mucin.

In osteomalacia and in the absorption of bone the mucous degeneration of the bone-cartilage plays an important part. The lime salts are first set free, and the cartilage then undergoes a mucous degeneration; the product is either absorbed or remains as a liquid within cavities of large or small size. The mucous metamorphoses of fibrous and fat-tissues, likewise of bone-marrow, are well recognized instances of the occurrence of a mucous transformation of the intercellular substance of connective tissues. Finally, clotted fibrin, so often met with as the product of the inflammation of serous surfaces, may undergo a mucous metamorphosis, and, thus transformed, offer a suitable material for absorption.

Colloid Degeneration, Colloid Metamorphosis.

Laennec used the term colloid in a descriptive sense to indicate a gelatinous appearance, and for a long time its use was thus restricted. As the colloid appearances were found to differ in their chemical reaction, their distribution, and their pathological importance, and as the term was further extended to include appearances seen with the microscope, it obviously became necessary to subdivide the colloid series of changes according to the observed differences. Its use is now limited to those gelatinous conditions or appearances due to the presence of a fixed albuminate, homogeneous or finely granular, translucent, colorless or pale {84} yellow, of varying consistency, which does not become fibrillated on the addition of acetic acid, and which does not change in color when acted upon by iodine. This albuminate is considered in most instances to represent the result of a transformation, a metamorphosis of cells, and is associated with an impairment of their function--a degeneration which is progressive, and leads, sometimes, to the destruction of the organ, as occurs in certain instances of colloid degeneration of the thyroid body. Usually, the process is limited, affecting particular parts rather than the whole of an organ. The reaction presented by a solution of sodium albuminate in the presence of neutral salts leads to the view that colloid material may represent a coagulation of an albuminous substance or substances under favoring conditions. The presence of colloid masses in the kidney thus meets with a plausible explanation.

The place of its typical occurrence is the thyroid body in certain cases of goitre, and it is early met with as a homogeneous substance replacing the granular cell-protoplasm. With its increase the latter disappears, and the entire cell is transformed into a homogeneous sphere. At times the colloid substance may be seen to project from the surface of the cell as a pale rounded clump. The aggregation of these clumps results in the presence of masses of various size, in which may be found granules of fat or pigment and crystals of cholesterin, which are accidental, not essential. Colloid masses are sometimes met with--in lymphatic glands, for instance--as concretions, mulberry-like aggregations of stratified colloid bodies, which may be infiltrated with earthy salts. Colloid material may eventually become liquefied, transformed into a sodium albuminate; and the presence of cysts in certain varieties of goitre is thus explained. The coexistence in the kidney of colloid accumulations and watery cysts has led to the view that the latter may, under certain circumstances, result from the former through the liquefaction of the colloid material. The same view is held with regard to the origin of cysts frequently met with in the choroid plexuses.

The colloid metamorphosis of cells is also to be found in the epithelium of mucous membranes and their glands, in the prostate, suprarenal capsule, sebaceous glands of the skin, and in the cells of certain tumors.

Amyloid Degeneration, Amyloid Infiltration, Waxy Degeneration, Lardaceous Degeneration.

The colloid appearances due to the amyloid degeneration of cells are of the greatest clinical importance from their frequent occurrence and the gravity of the symptoms connected with their presence. In amyloid degeneration there is the transformation of the cell-protoplasm into an albuminous material different from other albuminates found in the body. This transformation is at the expense of the functional activity of the cell, and the latter becomes inert. Amyloid degeneration represents no mere substitution, but an addition, since the affected tissue is increased in volume. The albuminate was called amyloid by Virchow in consequence of its color-reaction with iodine. Its method of origin is wholly unknown, never being found in the circulating fluids nor in articles of food. It is met with chiefly in the cell, although its presence in the intercellular substance of old people is recognized, and its occurrence in {85} the midst of the thrombotic deposition on inflamed valves and in the results of inflammatory processes is also recorded.

At present the question is under discussion whether the amyloid degeneration may affect cells of the most varied character, or whether it is limited to those of connective tissues. Eberth maintains that in all cases the amyloid disturbance is seated in the connective tissue. Kyber, the latest investigator, in opposition to this view maintains that this affection is not limited to the connective tissue, but may also be seated in the parenchymatous cells of organs. Whether the one of these views is to exclude the other, or whether both are not correct, remains for future investigation to decide.

Wherever the amyloid material may be situated, the result is a transformation of the cells into a homogeneous, glistening, colorless material, which occupies more space than the original cell, and, when abundant, is accompanied with a loss of the primitive details of the cell-structure. This material is recognized by the color it presents when acted upon by iodine alone, by iodine and sulphuric acid, or by methyl-aniline. The first produces a reddish-brown color, the second a blue, and the last a violet or purple color. These reactions are all characteristic, and the first is of special value in the macroscopic recognition of the process, while the last two are of special importance in the microscopic recognition of the earlier stages of the affection.

With the advance of the degeneration and its dissemination, the organ affected presents, in the diseased portions, pale-gray, glistening, translucent patches, and becomes increased in size and density in proportion to the quantity of amyloid material present. The change appears primarily in the vessel wall or outside the same, and there results a diminution in the calibre of the vessels, with a lessened quantity of blood in the organ.

From the homogeneous and translucent appearance of the surface and the increased density of the tissues the resemblance to bacon or wax is suggested, and the terms lardaceous, bacony, or waxy degeneration have been applied. Notable differences in degree and seat occur in connection with the organs diseased. In the spleen, for example, the change may be limited to the arteries of the Malpighian bodies and their immediate surroundings. To this condition the term sago spleen is applied, the enlarged, rounded, translucent, and projecting bodies suggesting granules of boiled sago. The appearances of the diseased part are further affected by the association of other conditions, as the presence of fat or pigment. When fat is present, it is often to be regarded as a result of the gradual and progressive increase in the obstruction to the circulation of blood in the organ.

Although so little is known of the immediate cause of amyloid degeneration, its distribution in the various organs of the body is fully ascertained, as well as certain of the conditions which are likely to be followed by its presence. It is known to occur as a localized process in cartilage, in the conjunctiva, in certain tumors, cardiac thrombi, scars, retained inflammatory products, and renal casts. The causes of this localized appearance are wholly obscure, and little or no general inconvenience results. Its presence, however, on a large scale and in various parts of {86} the body at the same time, is met with under such circumstances as indicate a distinct etiological relation. An appreciation of these circumstances is of importance, since their existence demands an investigation as to the probable presence of the degeneration. The organs thus affected are the spleen, liver, kidneys, and intestine. It is to their disturbance of function that the pathological importance of amyloid degeneration is to be especially attributed.

Other organs which may sometimes be affected are the lymphatic glands, pancreas, suprarenal capsules, omentum, uterus, bladder, prostate gland, heart, and thyroid body. In the case of a general diffused infiltration these organs are variously degenerated, now some, and again others, showing a more extensive alteration, while few or many may be simultaneously diseased. The longer the process has continued, the greater the degree of the disturbance and the larger the number of the organs infiltrated. Although, in general, a period of months and years may be demanded for these extensive changes, very serious disturbances may arise within a short time, and Cohnheim records several cases which suggest that widely diffused amyloid degeneration may occur within a few months--in one instance in less than four months.

All that is at present known with regard to the etiology of this process applies to certain general diseases with which in the course of time it is likely to be associated. These have one element in common, that of chronicity, and are likewise the occasion of a progressive wasting of the body. Of these affections, that which holds the first place is chronic pulmonary consumption, especially that form in which extensive destruction of the lungs and ulcers of the intestine are present. Another disease whose effects are in like manner to be regarded as general is syphilis, and in the later stages of this disease amyloid degeneration is likely to occur, and often to represent by its resulting disturbances the immediate cause of death. Again, chronic suppurative processes, especially those due to disease of the bones and joints, are a frequent antecedent of amyloid degeneration. Finally, the process has been found in connection with leucæmia, chronic intermittent fever, rickets, gout, and certain malignant tumors. This last group, however, is one in whose sequence the degeneration is to be regarded as exceptional.

The clinical importance of this process is due to the resulting disturbances in the function of such important organs as the liver and intestines, the spleen and lymphatic glands, and the kidneys. The nature of these disturbances obviously demands detailed consideration in connection with the description of the diseases of the respective organs. It may be mentioned here that the infiltration of the walls leads to a narrowing of the calibre of blood-vessels, and thus a diminution in the supply of blood to the part or organ. The resulting impairment of nutrition becomes enhanced from the condition of the blood, which is impoverished from the simultaneous infiltration of the blood-making organs. The nutrition of the individual thus suffers as well as that of the immediately diseased organ. Fatty degeneration and atrophy of the parenchymatous cells of organs like the liver and kidneys is the constant result of long-continued and extensive infiltration of these glands.

Mention is intentionally omitted of the so-called amyloid bodies, {87} corpora amylacea, considered in connection with amyloid degeneration in most text-books on pathology and pathological anatomy. They usually present a different reaction with iodine, their origin has but little in common, their distribution is for the most part unlike, and little or no clinical importance is to be attached to their presence.

Calcification, Ossification, Petrifaction.

When salts previously held in solution are precipitated under abnormal circumstances in the tissues of the body, the part is said to be calcified, ossified, or petrified. Although these terms are often used as equivalent, the last is to be regarded as more general than its predecessors, since it includes the deposition of other than the calcareous salts.

In the pathological ossification, as well as its physiological prototype, the carbonates and phosphates of calcium and magnesium are present in a specially formed tissue of the nature of bone-cartilage, whereas calcification occurs independently of such a new-formed tissue. The deposition of the calcareous salts takes place either in the cells or intercellular substance of living or dead tissues, when the terms calcification or ossification are applied, or as accumulations of various size in tissues or canals, which are known as concretions and calculi.