—Similar papillary and often pedunculated epithelial tumors frequently hang or project from the mucous membrane—e. g., the rectum. The pedicle really projects from the submucosa. Between the layers of the overgrown mucosa are found altered glands. So long as the growth of these polyps is toward the exposed surface they are innocent and wellnigh harmless, unless they attain fair size; but so soon as they grow inward and the boundary of the submucosa is transgressed they assume malignant aspects at once. Such transformation is by no means rare, and constitutes a strong argument for their prompt removal.
Goitre; Struma.
—Pathologically the various enlargements of the thyroid known as goitre or struma constitute essential neoplasms. (See chapter on [Regional Surgery of the Neck].) In this condition either the epithelial or the connective tissue may be primarily at fault.
1. Struma Parenchymatosa Nodosa.
—This includes also the colloid and the cystic varieties, and refers to an enormous overproduction of the epithelial elements (parenchyma) in distended alveoli, where they often undergo colloid softening. So marked are these changes in numerous instances that multiple cysts (minute or large) result. The collective volume of such altered tissue may be very large.
2. Struma Fibrosa.
—This presents itself in the way of dense enlargement of the thyroid, the stroma being the tissue now involved, even to the extent of causing much of the alveolar structure to disappear or become obliterated. In this condition calcification is common, and calcareous concretions or patches are often found.
Even benign tumors of the thyroid show occasionally a tendency to metastases. Cases are on record of benign goitre causing general metastases, and even of metastasis without noticeable thyroid enlargement. These occur most often in the bones, less frequently in the lungs and other organs. They are more common when the goitre has undergone colloid changes. The reasons for these changes are unknown.
In either form hemorrhages are common, with their resulting blood cysts or their solid residue, in which case pigment is usually found. Both forms are often accompanied by enlargement of the vessels, and sometimes these become enormously dilated and constitute an almost insuperable obstacle to successful removal. (See [Thyroidectomy].)