—Malignant neuroma (so called) will generally be found to be a true sarcoma of nerve structures, usually of the spindle-cell variety. Traumatic neuroma is often seen in amputation stumps, where the terminations of the divided nerves become bulbous, attaining the size of cherry stones, the tumors being composed of a mixture of connective tissues and nerve fiber, from which in time the true nerve structure usually recedes or vanishes. They form when suppuration has been profuse or healing long delayed, and when sufficient care has not been exercised to prevent entangling of the nerve ends in the scar of the wound. They give rise to much pain, and often necessitate re-amputation. The bulbous enlargement is the result of prolonged irritation in a nerve, and has been noted around various foreign bodies.
True neuroma is innocent in tendency, though often painful. It is the sarcoma of nerve tissue which produces signs of malignancy. A true neuroma which causes unendurable pain should, when accessible, be removed. It is sometimes possible to separate the tumor mass from the balance of the nerve trunk, and thus to remove it without excision of the nerve. At other times it is impossible to avoid division and ensuing paralysis. Divided nerve ends should be brought together by catgut suture, by which means it may be possible to avoid permanent loss of function. Nerve grafting is also resorted to for repairing such defects. Removal of painful neuromas due to injuries to the head has more than once been the means of curing traumatic epilepsy.
6. Tumors Derived from Epithelium.
These tumors consist of specific epithelial elements supported and more or less bound together by a vascular connective-tissue stroma. The only apparent exception to this statement is tumor of dental tissue. The teeth are positively modified and petrified or calcified epithelial products.
Odontoma.
—The odontomas are tumors composed of one or more of the dental tissues, arising either from tooth changes or teeth in process of development. They may be divided, according to Sutton, as follows:
1. Epithelial Odontomas.
—These are provided with a capsule, and present usually as a series of cysts separated by thin septa, containing mucoid fluid, while the growing portions have a reddish tint not unlike sarcoma. They are most frequent about the twentieth year of life, but may occur at any age. They probably arise from persistent remains of the epithelium of the original enamel organs.
2. Follicular Odontomas.
—These are often called “dentigerous cysts.” They arise in connection with permanent teeth, and especially with the molars, sometimes attaining great size and producing conspicuous deformity. The tumor consists of a wall representing the expanded tooth follicle, and a cavity containing viscid fluid, with some part of an imperfectly developed tooth, occasionally loose and more or less displaced in location. The cyst wall always contains calcareous material. These tumors rarely suppurate. They occur also in animals.