The thyroid body is occasionally the site of teratomas, i. e., tumors containing tissue of each blastodermic layer. No two such tumors are alike. They may assume various sizes and shapes, growing in various directions, and will hardly define themselves until removal.
The benign solid tumors consist mainly of the various types of goitre.
Of the malignant tumors, sarcoma is perhaps the most frequent, and is met here in all its varieties. Endothelioma occurs here also, while true carcinoma can hardly be primary in the thyroidal tissue, but may frequently extend to it and invade it, thus seriously complicating a case already made desperate by its presence in the neck. Metastatic forms of true cancer may also occur here as elsewhere. For a growth of this kind there is but one resort, i. e., extirpation, but this will be difficult and usually inexpedient.
GOITRE; STRUMA; BRONCHOCELE.
The enlargement or hypertrophy of a part or the whole of the thyroid, now known universally as goitre, has been known also as bronchocele and trachelocele. The condition is one of unilateral or symmetrical affection, met with much oftener in women than in men, and particularly in certain regions. It is most prevalent in Switzerland and in Upper India. It is occasionally known to assume an endemic or epidemic form, the affection disappearing from the region of the country concerned after a period of some years. Practically nothing is known of its cause. Many theories have been advanced, that which finds perhaps widest acceptance referring to the character of the water supply.
For present purposes goitre may be understood to include the following forms:
- Simple hypertrophy, the so-called parenchymatous form;
- Thyroid adenoma;
- Cystic goitre;
- Exophthalmic goitre (Graves’ or Basedow’s disease).
The parenchymatous form consists essentially of an overgrowth of the ordinary thyroid tissue. It is diffuse and unencapsulated, all the thyroidal tissues participating in its structure. Sometimes whole families suffer from this form of goitre, and occasionally an apparently hereditary influence may be traced. The tumor thus produced may attain great size. According as it involves one side or both will it be symmetrical or otherwise. It is elastic, smooth, rounded, sometimes apparently subdivided by furrows which mark the original lobar arrangement. It displaces the structures around it, and may attain a large size without producing serious pressure effects. When these occur they assume the type of dyspnea, dysphagia, and laryngeal paralysis. The growth is insidious, usually increases markedly with each pregnancy, and may spontaneously recede. Within it changes may occur which lead either to cystic softening and formation of cysts, or fibrous trabeculæ may appear and thus make it more firm and dense. The denser the growth the earlier the pressure symptoms appear. Occasionally the isthmus alone will appear involved, in which case there will be a central growth.
The so-called thyroid adenoma (the term adenoma being used on the supposition that thyroidal tissue is true gland tissue) is often of cystic type. It consists of more or less isolated tumors of general thyroid character, but circumscribed, often encapsulated, perhaps undergoing cystic degeneration, occurring frequently in multiple form, and producing cysts of all sizes. Such a growth will displace the other thyroidal tissue and may give a decidedly irregular aspect to the resulting tumor. The cysts often contain cholesterin. In recent cases the capsule is thin; in old tumors it may be calcified, and so may be the tissue within the capsule. These growths are seen in successive generations of the same family. They have their beginnings usually in the earlier years of life.
Similar growths may also arise from the outlying portions of the thyroid, or from accessory thyroids, so that they may be found back of the sternum, or lying deeply in the neck or near the base of the tongue. If near the surface and cystic they give a sense of fluctuation which the harder forms do not afford.