Strictly speaking, very few adventitious growths are developed in and from the parenchyma of mucous membranes themselves: for, with the exception of teleangiectasis, tubercle, and cancer, and of these indeed, only particular conditions and forms, almost all the new growths belong to the submucous cellular tissue. But as that tissue is intimately connected with the mucous membrane over it, so are also the new growths that originate and spread in it. The mucous membrane becomes involved in various ways, as may be deduced from the following remarks. There are, moreover, several other affections of the same class to which mucous membranes are subject only after having undergone a previous change of texture.

A. Growths Of Horn And Hair

Growths Of Horn And Hair have, in a few cases, been seen upon different mucous membranes, particularly on the conjunctiva, the mucous membrane of the intestinal canal, and that of the urinary bladder.

B. Lipoma

This growth is almost confined to the submucous cellular tissue of membranes near which a considerable quantity of fat is occasionally deposited. It is by no means rare in the submucous cellular tissue of the intestinal canal, especially of the small intestines; and it is met with also, but less frequently, in the stomach. It forms a rounded tumor, with a broad, or a somewhat constricted base; its size is mostly inconsiderable; it protrudes into the cavity, and is covered with the lining membrane of the organ in which it is developed.

C. Cysts

Cysts are formed in cellular or other submucous tissue, but they very rarely occur. They displace and stretch the mucous membrane, and, when of large size, even produce attenuation and atrophy of it.

D. Fibroid Tissue

Fibroid Tissue occurs as a. An adventitious fibroid growth of various size in submucous tissues: as such it presents itself under two forms, the second of which, for several reasons, is of much importance.

One of these forms is that of spherical, oval, or subovate, bluish-white, tough and elastic, concretions, the texture of which is very compact. It occurs in extensive tracts of submucous cellular tissue, particularly in the stomach and intestinal canal, and forms movable tumors which protrude inwards: they are very seldom larger than a pea.

The other form is that which has been named fibrous, to distinguish it from the mucous or cellular polypus; an adventitious growth of fibrous, and for the most part lax, texture, vascular, succulent, apt to swell, and generally more or less lobulated towards its periphery. It takes root by a single or by several stems, in submucous tissues of fibrous or muscular texture; it then grows towards the cavity of the organ, and thrusts before it a covering of mucous membrane. If it reach a large size, it expands the cavity on all sides; but if there be any hindrance to its increasing in the direction of the cavity it will grow principally in one direction, in either case destroying the walls of the cavity, even though they be of bone. Of this kind are the large fibroid growths, also named sarcomatous polypi, that spring from the submucous periosteum of the nares and adjoining cavities, from that of the basilar process of the occipital bone (the upper wall of the pharynx), from the perichondrium of the cartilages of the larynx, and from the innermost (submucous) layer of the substance of the uterus.

B. Fibroid tissue occurs also as fibroid and cartilaginiform thickening of the walls of mucous cavities which have been converted in the way already described into serous cavities: the fibroid tissue may then, as in the case of membranes originally serous, be deposited as an exudation upon the surface of the new membrane, or as a subserous production, beneath it. Under the same conditions, that is to say, only after the mucous membrane has undergone this complete change of texture.

E. Anomalous Bone

Anomalous Bone is formed upon it, or ossification, as it is called, takes place: and this again may be a subserous production or an ossified exudation on the surface. Cavities of mucous membrane are in this manner sometimes converted into bony capsules; but the only instance in which I have observed it is the gall-bladder.

F. New Growths Of Cellular Tissue

New Growths Of Cellular Tissue, or condylomata, occur upon some mucous membranes, especially upon the female organs of generation, in the mouth, etc.

G. Teleangiectasis

Congenital vascular naevi are, on the whole, a rare occurrence in mucous membrane, especially if those be excepted which extend from the skin to adjoining mucous textures, as, for instance, from the skin of the face to the mucous membrane of the lip. When they do occur, it is usually in the form of bluish-red, flattened or irregular, elevations of various sizes, and rarely in that of actual tumors or excrescences: they may be most frequently observed on the inner membrane of the intestinal canal.