Adventitious formations occurring in the air-passages are of the highest importance when they project into the interior of the air-passages in the form of broad or pedicled vegetations, and thus give rise to more or less contraction of their calibre. They occur almost exclusively in the larynx, and they are classified and treated of, according to their external characters, under the general head of laryngeal tumors. When considered in reference to their internal structure, they may be reduced to the following forms, which may be developed in and under all mucous membranes.

1. Epithelial Formations

These occur in the form of roundish cauliflower or wart-like growths, varying from the size of a hempseed to that of a hazel-nut, and are occasionally even larger; they are attached by a short pedicle to the mucous membrane, present a somewhat lobular and laminated structure, and consist of exuberant epithelial cells and very delicate vessels, prolonged, as it were, from the mucous membrane. They are especially liable to occur on the vocal chords and arytenoid cartilages, but they are sometimes found on the under surface of the epiglottis, and on the cricoid cartilage. As they frequently spring from a cancerous basis, they are often of a malignant nature, but they have also been observed in a non-malignant form in persons of various ages after catarrhs and repeated attacks of croup. They are the most common of all laryngeal tumors.

2. Cellular Or Mucous Polypi And Condylomatous Excrescences

These occur upon or in immediate proximity with an ulcerated basis, or when there are no existing ulcerations, they form hard or spongy purple vegetations varying from the size of a pin's head to that of a hemp-seed or pea, lying sometimes in great numbers closely beside one another, and occupying large portions of the laryngeal mucous membrane. Their favorite seat is the mucous membrane of the vocal chords. They are most probably of a syphilitic nature, and when, as is sometimes the case, they are associated with tuberculous laryngeal phthisis, and constitute the tuberculous ulcer, we are led to suspect that they originate in a combination of the tuberculous with the syphilitic dyscrasia.

3. Erectile Tissue

Erectile Tissue occurs in the form of broad-based, soft vegetations, capable of being rendered turgid, or as the development of the free extremities of mucous polypi. The former variety not unfrequently springs from a cancerous basis.

4. Fibrous Tumors

These are extremely rare in the submucous areolar tissue of the mucous membrane lining the cavity of the larynx, but are more common beneath the pharyngeal mucous membrane investing the posterior wall of the larynx. They are here often found not only of their ordinary inconsiderable size, but sometimes of a very large volume, and by their adhesion to the pericardium, remind us of the large pharyngeal polypi springing from the submucous periosteum.

5. Cancer

We have already remarked that cancer not unfrequently forms the basis of exuberant epithelial formations and erectile tissues. It further occurs in the larynx as fibrous cancer, in the submucous areolar tissue as a medullary cancer, and (which is extremely singular) as cancerous degeneration of the arytenoid cartilages. According to the volume of the morbid product, there are found larger or smaller nodular roundish protuberances into the laryngeal cavity, which thus becomes more or less diminished in size. These cancerous tumors, for the most part, prove fatal while still in their state of crudity; they sometimes, however, undergo their ordinary course of metamorphosis, and give rise to a cancerous ulcer.

Cancer also occurs in the trachea and bronchi, but in such cases it is almost invariably only a secondary affection. Thus it occasionally happens that the trachea is perforated by surrounding masses of medullary cancer in the neck; more frequently, in which case, the bronchi may also be affected, by cancerous accumulations in the mediastinum posticum, or by cancer of the oesophagus; and in these cases the air-passages become contracted by the growth of vegetations within them. In the bronchi we sometimes observe an ordinary cancerous degeneration of the fibrous sheath, proceeding in different directions from a bronchial stem along its ramifications, by which their walls are thickened and rendered rigid, and their calibre is diminished, while their inner surface becomes nodular and uneven. This degeneration appears to arise from cancerous disease of one or more of the bronchial glands.