Tumors may be divided into five classes. I. Cystic tumors, which may be again divided according to their contents into what are called (a) dermoid cysts, having their commencement iu the derma; or skin, including 'three varieties; those containing epidermis; those containing true skin, hair, and glands; those containing cartilage, bone, and teeth. See Cutaneous cysts in Tumors, ante. (b) Serous cysts, occasioned by dilatation of sacs, cavities, or canals, including blood-vessels, most frequently situated about the neck, but met with in almost every situation. They arc lined with fiat endothelium (epithelium), like that lining serous cavities generally. See SE1LOCS 3LEMBRAXES, ante. A variety of serous cysts called multiloetzlar (many-celled) are frequently met with in the ovaries, and constitute one form of ovarian dropsy or tumor. The ovarian cyst may also be uuilocular (one-celled). Sanguineous cysts (hematoma) are a peculiar' variety which have been well described by sir James Paget as chiefly occurring about the neck, parotid gland, and anterior part of the thigh, leg, and shoulder. They contain fluid blood more or less altered. They may be formed in three ways: by hemorrhage into a previous serous cyst; by transformation of IltEVUS (q.v.); or by occlusion of a vein. (A peculiar form of hematoma of the ear is often met with in the insane). The term hematoma is also applied to those cysts which result front changes taking place in extravasated blood, as in the brain. Other serous cysts are formed by accumulation of fluid in the meshes of the areolar tissue, and by changes in the products of inflammation. (e) Colloid cysts, arising from colloid (gluey) degenera tion of pre-existing cells, and from colloid degeneration of new cells. Other cysts are formed by the development of parasites, the most common of which is the hvdatid cyst arising from the presence of the young of tzenia echinococeus. 2. Tumors composed of one of the modifications of fully-developed connective tissue, such as fatty tumors (lipoma,) fibrous or fibroid tumors,- and fibro-cellular tumors (fibroma), cartilaginous tumors (chondroma, see ENCILONDROMA, ante), bony tumors (osteoina, exostosis). The causes of exostoris are obscure. In some instances they are hereditary. The disease is usually met with at about the age of puberty. There are two modes of development; primarily as true bone, and secondarily from previously formed cartilage. Exostosis may be simple or multiple, and are of two kinds, hard, or ivory exostosis and spongy, or cancel/a/is exostosis. Another variety of these tumors of the second class is rnyxoma or mucous tumor. This has been classed by some writers as a variety of sarcoma. Many tumors formerly described as colloid cancer belong to this class. These tumors usually appear in the form of round, oval, or lobular masses surrounded by a loose capsule of connec tive tissue. They are elastic and gelatinous, and of slow growth. When cut they present generally a delicate pink color, but are sometimes yellow, and pour out an abundance of a glairy. tenacious fluid resembling gum water. A microscopic examina tion shows a beautiful arrangement of branched cells and net-work. Virchow regards these tumors as closely related to embryonic fat. 3. Ittmors which resemble in structure more or less perfectly one of the more complex tissues of the body. One variety of these is myoma, or muscular tumor. There are two classes, one containing striated, and the other non-striated, muscular fiber. Belonging to this class are neuromas, or nervous tumors, rare growths when strictly growing out of nervous tissue. They are always non-malignant, and should never be interfered with except when giving pain. Angiomas are tumors composed of vascular tissue of new growth; one variety is mucus (q.v.) Other tumors of this class are lymphangioma, a tumor composed of lymphatic vessels; Zymphadenoma, one composed of tissue like that in the lymphatic glands, and papitioma, a tumor resembling the papillre of the skin or mucous membrane, and including such growths as corns and warts (q.v.). 4. Tumors composed of tissue which is either purely embryonic, or as showing some signs of a tendency to develop into adult tissue of the connective type. These tumors comprise the sarcomas, or sarcomata, growths which have been the subject of much controversy, but whose classification is now pretty well settled. Many
until recently were known under a variety of names, and grouped in other divisions Formerly the term sarcoma was applied to almost any soft fleshy growth. The soft sarcomata of bones and of secreting glands and lymphatics were formerly called soft cancer, and melanotic sarcomata were called melanotic cancer. Hard, firm sarcomata were often described as hard cancer or scirrhus. The tumors described by sir James Paget as fibro-plastic, fibro-nuclear, recurrent-fibroid, etc., have all been brought into the great class sarcoma. These tumors may grow in any part of the body, and present every variety of consistence, color, and form; they may be circumscribed or diffuse, and as benign, as a fatty tumor, or as malignant, as the worst form of cancer. The anatomical type of sarcoma is found in the embryonic tissue. See DEVELOPMENT OF THE EMBRYO, ante. Its pathological type is seen in the cellular products of inflamma tion, with the particular difference that inflammatory new growths tend to limit them selves, whereas sarcomata have a tendency to indefinite growth, and the individual elements (cells) arc often much larger, and have less tendency to form tissue. It is chiefly according to the size and form of the cells that sarcomas are divided into varieties. We have space here to scarcely more than mention the names of these varieties. Small sound-celled sarcoma, or granulation sarcoma (formerly called encepbaloid cancers), and resembling superficial layers of granulations in healing wounds, being composed of small round cells about the size of white blood-corpuscles. Spindle-celled sarcoma, formerly called recurrent-fibroid tumor, and libro-plastic tumor, a growth composed of spindle shaped, fusiform cells, either lying in contact or separated by a homogeneous or fibrous intercellular substance, the cells varying greatly in length, from to more than iLT of an inch. Oval-celled sarcoma is a variety of spindle-celled, of very rapid growth and great malignancy. Myeloid, or giant-celled sarcoma, formerly classed as fibro-plastic, and sometimes as soft. cancer, and by Abernethy called albuminous sarcoma, whose peculiar characteristic is the presence of large, many-nucleated masses of protoplasm, resembling the cells found in the marrow of fetal bones. The cells are sometimes to of an inch in diameter, and of irregular shape, the nuclei varying from ten to forty in number, of oval shape, and having highly refracting nucleoli. These myeloid cells are imbedded in masses of spindle-shaped or roundish cells. These tumors are extremely vascular. Ossifying and osteoid sarcomata, formerly called bone, or osteoid cancer. Almost any form of sarcoma may undergo ossification, the varieties already mentioned often showing abundant formation of bone. Alveolar, or large round-celled sarcoma, occurring chiefly in the skin, bones, and muscles, and difficult of distinction from hard cancer. Nebula& sarcomata, or formerly regarded as melanotic cancer, was carefully studied by Carswell, and arranged under the heads punctiform nielanosis, tuberiform melanosis, and stratiform melanosis. These growths are usually of the spindle-celled variety, but contain large numbers of round or oval, and fusiform cells. The spindle-cells are large, and there is no fibrous material. The pigment consists of a brown granular matter in the interior of many of the cells, while the remainder are colorless. They are usually developed in those situations where pigment naturally exists, as in the skin, and the choroid coat of the eye-ball, but sometimes are found in the lymphatic glands. They are of rapid growth, and usually occur in middle life. They are among the most malignant of tumors, and the secondary deposits occur in every part of the body, being distributed either by the vascular system alone, or by both blood-vessels and lymphatics. If a melanotic sarcoma has reached the size of a filbert it may be concluded that secondary deposits have already taken place,_and that the disease has reached a rapidly fatal stage. Of other forms of sarcoma there is no space for mention. This brings us to the consideration of the last class of tumors. 5. Tumors composed of cells of an epithelial type arranged in spaces in a stroma consisting of more or less perfectly developed fibrous tissue. This group constitutes the cancers or carcinemas. See CANCER, ante.