As a consequence of increase of nutrition we have a condition known commonly as hypertrophy, more accurately as hyperplasia. Hypertrophy literally means overgrowth, whereas hyperplasia more accurately describes that which constitutes hypertrophy—namely, numerical increase of constituent cells. Common usage has made the more inaccurate name “hypertrophy” cover nearly all these conditions. Hypertrophy, or hyperplasia, means enlargement of a part or of an organ beyond its usual limits, and as the result of increased function or increased nutrition. It is to be distinguished from gigantism, which means inordinate enlargement as the result of a congenital tendency or condition. Hypertrophy is—
| A. | Physiological | - | 1. | Compensatory; | |
| 2. | From deficient use. | ||||
| B. | Pathological | - | 3. | Local; | |
| 4. | General; | ||||
| 5. | Senile; | ||||
| 6. | Congenital. | ||||
Fig. 1
Congenital hypertrophy: gigantism of both lower extremities. (Case of Dr. Graefe [Sandusky].)
A. Physiological Hypertrophy.
—1. This includes many of the compensatory enlargements of an organ or a part when extra work is put upon it, owing to deficiency of some other organ or part. This is spoken of as compensatory enlargement. Illustrative examples may be seen in the heart, which becomes larger and stronger when the bloodvessel walls are diseased and their lumen narrowed, or when other obstructions to circulation are brought about; again, in enlargement of one kidney after extirpation of the other, or of the wall of the stomach when the pylorus is constricted or obstructed; again, of the fibula after weakening or more or less destruction of the tibia, or of the shaft of any bone when it has been weakened at some point by not too acute disease; or, again, of the walls of bursæ after constant friction.
2. The best examples of physiological hypertrophy owing to deficient use are perhaps seen in some of the lower animals; as, for instance, in the teeth of such rodents as beavers when kept in captivity and prevented from natural use.
B. Pathological Hypertrophy.
—3, 4. Instances of this are everywhere and every day are met in the results of so-called chronic inflammation, a term which is a complete misnomer and should be expunged from text-book use. So-called chronic inflammation simply means increase of nutrition owing to a certain degree of hyperemia, which may have been produced in the first place as the result of traumatism, which may have come from chemical irritants circulating in the fluids of the part—as, for example, uric acid, etc.—or which is brought about as the result of perverted trophic-nerve influence. Instances of local pathological hypertrophy may be seen in the thickened periosteum after injury, in the enlargement of a phalanx known as the “baseball finger,” and in numerous other places; or they may be general, in which case they are brought about mainly by some irritating material in the general circulation. The unknown poison of syphilis generally provokes such nutritive disturbances.