Postgraduate Medicine

ISSN: 0032-5481 (Print) 1941-9260 (Online) Journal homepage: http://www.tandfonline.com/loi/ipgm20

Thyroid Nodule John F. McKenney MD To cite this article: John F. McKenney MD (1975) Thyroid Nodule, Postgraduate Medicine, 57:7, 103-105, DOI: 10.1080/00325481.1975.11714077 To link to this article: http://dx.doi.org/10.1080/00325481.1975.11714077

Published online: 07 Jul 2016.

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Date: 11 February 2017, At: 20:50

co sder • What is the risk associated with the use of only one treatment modality in ali cases of thyroid nodule? • Do the physical characteristics of a nodule suggest whether the lesion is benign or malignant?

JOHN F. McKENNEY, MD Scott and White Clinic Temple, Texas

Thyroid Nodule Recent advances in endocrinology have resulted in a better understanding of both the physiology and the pathophysiology of the thyroid. New diagnostic aids permit a more detailed study of the architecture and the function of the gland. The tremendous progress is readily appreciated when one recalls that not too long ago the basal metabolic rate and blood cholesterol determinations were the main laboratory methods used to evaluate all thyroid problems, while iodine and thyroidectomy plus hormone replacement using desiccated thyroid were the only therapeutic modalities available. Much remains to be learned, however, before many of the perplexing problems which confront the clinician can be solved. The management of many thyroid conditions remains controversial even though specifie laboratory studies now allow more accurate diagnosis. Especially in dispute is the treatment of nodular goiter-whether the goiter contains a solitary nodule or is multinodular, whether it is taxie or nontoxic. There are physicians who think that ali nodular goiters should be treated by using thyroid hormones to suppress thyroid function. Others take the diametric position, that all nodular goiters should be ablated and that none should be treated medically. The proper approach probably lies somewhere between these therapeutic pales. The invariable use of only one treatment modality indicates failure to consider the multiple possible causes of a palpable mass or

Vol. 57 • No. 7 • June 1975 • POSTGRADUATE MEDICINE

nodule in the thyroid. Such a mass may represent (1) a single adenoma, (2) hemorrhage into the gland, (3) lobulation of normal thyroid tissue, (4) lobulation due to chronic thyroiditis, (5) a primary malignant lesion, (6) metastasis to the thyroid gland, (7) an intrathyroid cyst, (8) an autonomous nodule, (9) a malignant lesion associated with thyroiditis, (10) hyperplasia of one lobe caused by congenital absence or surgical removal of the contralateral lobe, or (11) other clinical entity closely associated anatomically but not thyroid in origin, ie, parathyroid adenoma or parathyroid or thymie cyst. Clinical Features

It is important to note the clinical features of a mass in the thyroid gland. The first consideration is whether there is a solitary nodule in one lobe or whether there are multiple nodules in one or both lobes. The initial clinical impression often is misleading, however. In our experience at the Scott and White Clinic, about 30% of patients with clinically diagnosed solitary lesions prove to have two or more nodules on subsequent exploration of the gland. These nodules are often, but not always, histologically similar in a given patient. The physical characteristics of a thyroid nodule or nodules are of sorne help in establishing

A glossary of abbreviations used in this symposium appears on page 59.

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Figure 1. Thyroid nodules as seen on scintiscan. a. Autonomous (hot) nodule, right lobe. b. Warm nodule, lower pole of left lobe. c. Cold nodule, lower pole of left lobe.

the diagnosis. In an otherwise normal gland, a soft, well-circumscribed nodule suggests a benign adenoma and a well-defined, firm nodule suggests a primary or secondary malignant lesion. When the gland is firm, a nodule suggests lobulation associated with chronic thyroiditis. In a series of patients with chronic thyroiditis seen at our clinic, 18% had associated benign adenoma and 2.8% had coexisting thyroid carcinoma. Tenderness or sudden enlargement of the gland or bath may indicate bleeding into the gland or into a preexisting adenoma. An easily palpated lobe rouch larger than the contralateral one suggests deep-seated adenoma, autonomous nodule, or absence of the contralateral lobe. Classification

Measurement of thyroid hormone concentration in the plasma distinguishes the states of hypothyroidism, euthyroidism, and hyperthyroidism but does not provide information relative ta the anatomie features of a thyroid lesion. By radioisotope scanning, nodules in the gland may be classified as hot, warm, or cold (figure 1)depending on the concentration of radioiodine (RAI) in the nodular tissue. A hot nodule (RAI concentration greater than that in surrounding tissue) functions autonomously, suppressing the thyroid-stimulating hormone (TSH) of the pituitary gland and in turn reducing function of the remaining normal tissue. The nodule thus appears on the scinti-

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scan as a clark area, with little or no evidence of radioactivity in the surrounding or adjacent normal portion of the gland. This type of nodule can be differentiated from congenital or surgical absence of the contralateral lobe by administration of TSH and repetition of the scanning procedure. If the nodule is hot, TSH will stimulate function of the surrounding tissue, which will then concentrate RAI. In our experience, an autonomous nodule has never proved to be malignant. Many autonomous nodules are entirely asymptomatic and the thyroid hormone concentration may remain within the normal range. It should be remembered, however, that hyperthyroidism may develop insidiously in such a gland. In other cases, nodules may produce clinical manifestations that suggest hyperthyroidism without the results of thyroxine determinations supporting such a diagnosis. In this situation, the serum leve! of triiodothyronine (T3 ) may be elevated, thus establishing the diagnosis of T 3 thyrotoxicosis. The optimal treatment of an autonomous nodule is ablation, which may be accomplished by using surgery or RAI. After surgical removal of the nodule, the remaining thyroid tissue will resume its normal function. The same result can be accomplished by using RAI. Before 131 I is used, T 3 should be administered for seven ta ten days ta insure complete suppression of the normal portions of the thyroid gland,

POSTGRADUATE MEDICINE • June 1975 • Vol. 57 • No. 7

thereby protecting this tissue from radiation. The 1311 is then trapped only within the autanemous nodule. A warm nodule (RAI concentration the same as that in the surrounding tissue) presents a more difficult and more involved diagnostic problem than does a hot nodule. A warm nodule in a firm gland suggests lobulation associated with chronic thyroiditis. If the tissue in the warm nodule and that in the rest of the normal thyroid gland are similar in consistency, the nodule may be nothing more than a lobulation of normal thyroid tissue. True warm nodules that are treated with thyroid hormones usually regress. If they do not regress after adequate suppression therapy, reevaluation is indicated, as the nodule may be a cold lesion. When studying a scintiscan of the thyroid gland, one must remember that it shows a threedimensional abject on a two-dimensional plane. Thus, a cold nodule (RAI concentration less than that in the surrounding tissue) embedded in normal thyroid tissue may give the appearance of a warm nodule on the scintiscan. A true cold nodule presents an even more difficult diagnostic problem than a warm nodule. Information obtained by palpation and by scintiscan is helpful but is not diagnostic. The only accurate appraisal of the nature of a cold nodule is obtained by microscopie examination. Treating a cold nodule exclusively with thyroid hormone indicates failure to take the various possible causes of such nodules into consideration. Carcinoma must be seriously considered as a diagnostic possibility in a patient who has a solitary cold nodule, especially if the patient is young or male or bath, as the incidence of carcinoma is higher under these circumstances. In our experience, the incidence of carcinoma is 15.6% in patients with a solitary nodule and 9.3% in those with multiple nodules.

JOHN F. McKENNEY Dr. McKenney is in the department of general surgery, Scott and White Clinic, Temple, Texas.

Definitive therapy can be applied only after a definitive diagnosis has been made. Until accurare preoperative diagnosis is possible, the thyroid gland must be explored or a 15% risk of a coexisting malignant lesion must be accepted. Summary

A palpable mass or nodule may represent any one of a large and diverse group of conditions that involve the thyroid. Whether the patient is euthyroid, hypothyroid, or hyperthyroid can be assessed, and the cause of hypofunction or hyperfunction can usually be determined. Scintiscanning provides important information on the anatomie structure of thyroid nodules. A hot nodule should be ablated by either radioiodine or surgery. A warm nodule usually responds to suppression therapy; if regression does not occur, the problem should be reevaluated. A cold nodule should be surgically excised, as microscopie study of such a lesion is mandatory. Address reprint requests to Publications Office, Scott and White Clinic, Temple, TX 76501. For ReadySource on thyroid management, see page 151. Summary self-test on thyroid management begins on page 144.

uestlon What circumstances should arouse suspicion that a supposedly warm thyroid nodule is in tact a cold nodule?

Vol. 57 • No. 7 • June 1975 • POSTGRADUATE MEDICINE

answe Failure of adequate suppres· sion therapy ta induce regression

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Thyroid nodule.

Postgraduate Medicine ISSN: 0032-5481 (Print) 1941-9260 (Online) Journal homepage: http://www.tandfonline.com/loi/ipgm20 Thyroid Nodule John F. McKe...
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