Enchondroma may occur in the mediastinum or lungs; it is rare as a primary process, but is more often found as secondary to enchondromata of the bones.22
22 Lebert, Physiol. Pathol., ii. p. 213; also, Förster, Virchow's Arch., xiii. p. 106.
ETIOLOGY.—Predisposing and Exciting Causes.—The etiology of morbid growths in the mediastinum, as elsewhere, is subject to debate and conjecture. The most practical query relates to location—viz. that sarcomatous growths originate in the anterior mediastinum, and carcinoma more frequently in the posterior.
The trade of shoemaker was followed by several subjects of sarcoma observed by the writer. These men were accustomed to press the last against the sternum. With a pure family history free from taint of malignant disease the etiology of sarcomata may be more readily linked with some cause of irritation than is the etiology of cancerous tumors. This irritation may be a blow or other direct injury or some local irritation, as antecedent inflammatory process in the lungs, bronchial mucous membrane, or pleura. Intemperance, insufficient food, and over-exercise have been noticed in rare instances as antecedents. In reference to lympho-sarcoma, preceding causal irritation may have existed, but in two-thirds of the cases the etiology is obscure. Hereditary transmission has not been distinctly proven in regard to any of the forms of sarcomata. The etiology of cancerous tumors is still more vague, though possibly the previously-named conditions may have preceded the growth. Louis, speaking generally upon intra-thoracic cancer, places it fourth in the scale of comparative frequency of organs affected—viz. uterus, stomach, liver, and lungs. The history of the removal of a morbid growth may attest the secondary character of some growths apparently primary.
In the question of age and sex the autopsies at Kronstadt already referred to show that in 158 malignant growths 127 were carcinomatous; 81 occurred in men of an average age of fifty-three, and 46 in women of an average age of fifty-six. So we may conclude that carcinomatous growths occur after the middle period of life. In 31 cases of sarcomatous tumors, 20 occurred in men of an average age of thirty-eight, and 11 in women of an average age of forty-eight. Powell gives 24.8 as the mean age for the occurrence of mediastinal growths in general. As a rule, a mediastinal tumor recognized at a relatively early period of life, before the thirtieth year, is most likely to be one of the forms of sarcomata. Sarcomatous tumors, however, sometimes occur in the aged; for example, in a woman æt. seventy-six (Laboriou23) and in a woman over sixty reported by Wilson.24 The question of liability through sex is somewhat uncertain, but while these growths may occur in either, a slight preponderance exists in favor of the male sex, especially if the growth be a lympho-sarcoma.
23 Virchow's Arch., loc. cit.
24 Trans. Path. Soc. Philada., Jan., 1884.
SYMPTOMS.—In studying the semeiotic characteristics of mediastinal growths an accurate history of the case is a prerequisite of paramount importance to a correct understanding of the essential features of the malady. It should be borne in mind that no single fact determined by the methods of physical diagnosis has special pathological significance, but simply indicates certain definite physical conditions in the region under examination. The purely objective physical signs are so closely intertwined with the general symptoms of morbid process that any study is partial which does not recognize this combination. Both physical signs and general symptoms must be in turn considered in connection with a thoughtful analysis of the processes of morbid anatomy, because symptomatology is the study of the expression of pathological changes. The general nutrition of patients suffering from primary sarcoma or lympho-sarcoma is often good in the early stages of the disease unless the oesophagus is pressed upon or implicated, and at the last patients may even die in a well-nourished condition. Indeed, the special import of the peculiar respiratory disturbance with pain seems set at naught by the appearance of fair health. In some cases of sarcoma or lympho-sarcoma, however, emaciation is progressive, though slower than in cancerous growths.
When cancer itself is primary, the ordinary characteristic train of disturbances of nutrition, with cachexia, follows, and then emaciation is rapid and decided. The loss of nutrition with anæmia is more marked in secondary sarcoma, and in cases of secondary cancer cachexia is the rule.
In reviewing the clinical history attention is specially directed to the development of the mediastinal growth by the gradual increment of subjective sensations of shortness of breath, with a sense of discomfort or tightness in the chest, with or without radiating pains. The respiratory phenomena present great diversity, yet the neurotic character of the dyspnoea is characteristic. Rest or change of posture may remove all oppression, or on the least exertion dyspnoea may be at once manifested. With limited physical signs there may be great distress of breathing or orthopnoea, while in many cases with unquestioned evidence of tumor there may be only a little quickening of respiration. As a rule, tumors of the anterior mediastinum are less characterized by dyspnoea than those involving the posterior space. The dyspnoea depends upon the size and seat of the tumor, and increases day by day with its growth; but in certain cases the tumor is so placed that pressure on the trachea, bronchus, or direct pneumogastric irritation may induce severe paroxysmal attacks of dyspnoea, with laryngeal symptoms resembling the condition so common in aneurismal tumors. Pressure symptoms, traceable to irritation of the pneumogastrics, are, however, as a rule, less marked than in aneurism. Pressure on the trachea without implication of the laryngeal nerves can occasion many of the symptoms usually assigned to the latter cause.25 Even when the tenth nerves have been surrounded or involved by the growth, special symptoms may be absent, although in other cases serious phenomena follow, such as vomiting or other gastric disturbance, or even inability to swallow; sometimes palpitation, angina, irregular action, or tendency to faintness may follow implication of the cardiac plexus.