NON-MALIGNANT TUMORS. These are composed of tissues of the types found in the adult and are in themselves not dangerous to life. although sometimes serious from pressure upon or involve ment of important organs. They do not as a rule grow as rapidly as do malignant tumors: they do not tend to recur when completely removed, do not form metastases, do not involve neighboring lymph glands, and do not as a rule interfere with the general health of the patient.
Fibroma—This tumor is composed of fibrillar connective tissue of the type found in the adult. Fibromata vary even more greatly in consistency than does ordinary fibrous tissue, those contain ing many fibres and few cells being hard and firm, fibroma durum those containing propor tionately. many cells being soft, fibroma .molle. They are commonly inclosed in a definite fibrous capsule. The softer fibromata are frequently very vascular, while the harder forms usually contain few vessels. They are found in the skin and subcutaneous connective tissue, in the connective tissue framework of the various or gans, in the mucous membranes, in the intermus cular septa, in nerve sheaths, etc. Mucous polypi of the nose are examples of this kind of tumor.
My.roma.—Myxomattt are tumors composed of tissue which resembles a type of tissue found only in extremely small amount in the adult and known as mucous tissue. Mucous tissue is there fore essentially embryonic. These tumors re semble the fibromata in structure, being made up of conneetive-tissue cells with a fibrillar inter cellular substance. The softer tumors are known as my.roma grlatinosum, or myxoma molls, while those of greater consistency are known as inyX0 rtia medullare. Myxoma is of comparatively rare occurrence in pure form. More commonly myxo ma ta, are combined with tumor tissue of other types to form complex tumors of which the most common are lipo-myxoma and fibro-myxoma. They most frequently develop in fat.
Lipoma.—Lipomata are fatty tumors. They may be quite firm from the presence of fibrous.
tissue, fibro-lipoma, or soft, li7Joma molle. Lipo ma is a very common form of tumor, being often superficial, developing in the subcutaneous fat. Lipomata may, however, develop anywhere where fat is found and consequently have a wide dis tribution. They are generally inclosed in firm fibrous capsules and occur usually on the shoul ders, back, or forearms.
Chondronia.—These are tumors in which the new-formed tissue resembles cartilage of either the hyalin or fibrous variety.
Ostcoma.—Osteomata on bony tumors are rather rare as pure tumors. Associated with other forms of tumor tissue (as osteo-sarcoma, osteo-fibroma, etc.), they are more common. Osteomata as a rule develop in bone. Less com monly they originate in other tissues.
Glioma.—Gliomata are connective-tissue tumors which follow the structure of the nervous system connective tissue, or neuroglia. Glioniata are soft and usually vascular, thus predisposing to hemorrhage. They are also extremely liable to fatty degeneration. As a pure type they are rare. Associated with other forms of connective tissue new growths, the glyo-sarcoma, glyo-myxo ma, etc., they are more common. They occur chiefly in those parts of the nervous system where neuroglia is found, e.g. in the brain and cord, the ganglia, and in the optic and olfactory nerves.
Myonza.—Myoniata are tumors whose tissue elements are analogous to those found in muscle tissue. Like normal muscle, they may be divided into two forms, one in which the tissue elements are smooth, or involuntary muscle, the other in which the tissue elements are striated, or vol untary muscle. To the former the name `leiomy oma' or 'myopia levicellulare' has been given, to the latter the name of `rhabdomyoma' or Myoma. striocellulare.' )Noma is rare.
.heuroma.—Neuromata are divided into true neuromata and the so-called false ueuromata. True ne.uromata are extremely rare. They con sist of nerve tissue and may he of the ganglionic type in which new nerve cells develop, or of the fibrillar type which consist of new-formed nerve fibres. .Ncuromata may he single or multiple, the latter frequently occurring along the branches of distribution of a single peripheral nerve. They occur in stumps after amputation of a limb and are often extremely painful. The 'false neuro mata' are not nenromata at all, but fibromata. sarcomata, myxontata, etc., of the connective tissue of the nerve trunks.
Angionia.—These tumors consist of newly formed blood or lymph vessels and are of two kinds, liwmangioina and lymphangioma. The former are subdivided into simple angioma or ngioma• telangiectoides and angioma caverno sum. The simple angioniata are composed of masses of blood vessels, mainly capillaries, held together by connective tissue. The so-called `strawberry' marks or vascular nawi, usually of the face, are congenital tumors of this varie ty.