The Pathology of the Nodular Goiter

Abstract

SUMMARYPathologic studies of thyroid nodules indicate that a definite percentage of nodular goiters are malignant, and that an even higher percentage are true neoplasms. Malignant tumors may arise from adenomas, involutionary nodutes or possibly from nodules of the unclassified type. Some carcinomas of. the thyroid gland are undoubtedly malignant processes from the start. Because of the high incidence of neoplasms, benign and malignant, in a group of single nodules of the thyroid gland, the presence of such nodules should warrant radical resections of the involved lobe and adjacent isthmus. The high incidence of epithelial growth activity in nodular involutionary goiters may revise the accepted practice of removing non-toxic nodular goiters only when clinical evidence of growth or local pressure is present.A VARIETY of pathologic processes in the thyroid gland may produce nodular enlargement or goiter. In studies of three series of patients with nodular goiter,1' 2'4 a classification of these nodules was proposed. Nodular goiters fall into four general groups: (a) involutionary nodules, (b) neoplasms, benign and malignant, (c) unclassified nodules, (d) miscellaneous nodules, including cysts and thyroiditis nodules.As has been shown by Reinhoff and Lewis,3 involutionary nodules originate as focal areas of hyperinvolution in a hyperplastic gland. Usually this hyperplasia is not associated with hyperthyroidism. It is cyclic and seems to be associated with demands upon the thyroid gland for thyroid hormone, especially in the female during pregnancy, lactation and the menopause. In the beginning, these involutionary nodules are small. They are composed of enlarged alveoli which are filled with colloid. As they enlarge further, they compress the surrounding thyroid glandular tissue, cause atrophy of its epithelial elements and compress the supporting stroma so as to produce a fibrous capsule. These nodules generally are called adenomas, but since they have their origin in an irregular hyperinvolutionary process, they should not be considered as true neoplasms.Once the involutionary nodule forms, it may enlarge greatly over a period of years by a number of