99mTc-pertechnetate thyroid scintigraphy in patients predisposed to thyroid neoplasms by prior radiotherapy to the head and neck

Clinical significance of focal and diffuse thyroid diseases identified by 18F-fluorodeoxyglucose positron emission tomography

(18)F-Fluorodeoxyglucose positron emission tomography (FDG-PET) thyroid incidentalomas are defined abnormal FDG uptake in the thyroid gland found at PET scan performed as part of a staging protocol and follow-up of patients with various kinds of malignancies. In the present study we report two cases of FDG PET thyroid incidentalomas, and review the literature with regard to the meaning of this new category of thyroid "disease". Since the advent of whole body FDG PET scan, a relatively high incidence of cases of thyroid FDG uptake has been reported as an incidental finding as in one of our patient. Focal uptake was found to be more likely associated to a malignant lesion, while a diffuse thyroid uptake to a benign thyroid disease. However, differential diagnosis is difficult, and reported data in literature are somewhat discordant. A focal thyroid uptake of FDG incidentally discovered at PET scan cannot be invariably considered a malignant thyroid nodule, however a prompt and complete work-up including laboratory examinations, ultrasonography and fine needle aspiration cytology, should be obtained to exclude a thyroid carcinoma. On the other hand, patients with a PET finding of diffuse FDG uptake can be considered at low risk of malignancy, being more likely associated to chronic thyroiditis or diffuse thyroid autonomy.

A differential nuclear uptake and retention of 3H-androgens in the thyroids of baboons

Women have a greater incidence of autoimmune thyroiditis, thyroid cancer and radiation-induced carcinogenesis than men. Over the past several years we have examined for the presence of steroid receptors in both humans and non-human primates. In this study we examined the nuclear uptake and retention of 3H-testosterone, the main circulating androgen in mammals, in different cells of the thyroid gland of baboons, our non-human primate model. Castrated-adrenalectomized male baboons were injected with 3H-testosterone (1 microgram/kg bw) and killed 1 1/2 h later. The thyroid glands and other tissues were removed and processed for autoradiography. Nuclear localization of 3H-testosterone or one of its metabolites was found in a small fraction of the follicular cells (approximately 10-20%). The discrepancy between these findings and those previously obtained with 3H-dihydrotestosterone (virtually 100% of the follicular cells concentrated the 3H-steroid) are discussed. The results from this study and those of the past strongly support a direct action of androgen on the thyroid. Whether a direct action of androgen on the thyroid is related to smaller incidence in autoimmune thyroiditis, thyroid cancer and radiation-induced carcinogenesis in men than women remains an unanswered question at the present time.

Differentiated thyroid cancer in children

Differentiated thyroid cancer in children remains a controversial disease entity. Its incidence has markedly declined over the last decade since the use of radiotherapy in the treatment of benign conditions of the head, neck, and thorax was abandoned. Other etiologic factors have become relatively more important. The clinical presentation of childhood thyroid cancer is similar to that found in adults, except for a higher frequency of local and distant metastases at the time of initial diagnosis. The specificity and sensitivity of diagnostic tests are limited; however, like in adults, fine-needle aspiration compares favorably with other available diagnostic methods. The therapeutic approach to a child with thyroid cancer represents the most controversial issue associated with the disease. This review provides a discussion of the rationale for the different therapeutic options and emphasizes the excellent prognosis and survival rates, especially when patients are subjected to aggressive treatment with total thyroidectomy followed by the administration of radioactive iodine.

Thyroid abnormalities associated with treatment of malignant lymphoma

The effects on the thyroid of radiation therapy to the neck and/or chemotherapy were investigated in 54 Hodgkin's and 72 non-Hodgkin's lymphoma patients. These patients had received radiation therapy with doses ranging from 2000 to 4000 rad (median 3600 rad) to the cervical or mantle fields and/or multiple-agent chemotherapy following usual staging procedures. Palpable abnormalities of the thyroid were found in 15 patients. The patients with irradiation to the neck had a higher incidence of hypothyroidism than those patients treated with chemotherapy alone (31/74 vs. 8/52, P less than 0.001 for TSH and 10/74 vs. 1/52, P less than 0.025 for T4). A higher frequency of elevated serum TSH levels and antithyroid antibodies were also observed in patients receiving radiation therapy alone to the neck than in those receiving both radiation therapy and chemotherapy (19/33 vs. 12/41, P less than 0.025 for TSH and 16/33 vs. 7/41, p less than 0.01 for antibodies), suggesting that chemotherapy agents may reduce the thyroid dysfunction induced by irradiation. There was no difference in prevalence of elevated TSH levels following irradiation to the neck between patients in whom lymphangiogram was or was not performed (21/51 vs. 10/23).

Thyroid disease: a guide for the head and neck surgeon

Head and neck surgeons are involved in the diagnosis and therapy of thyroid disease with increasing frequency. The surgical techniques utilized for the management of thyroid disease are well known by most head and neck surgeons and will not be discussed in this paper. It is the head and neck surgeons' knowledge of the physiology, medical disorders, and the proper evaluation of the patient with thyroid disease that is most open to criticism. This paper reviews thyroid physiology, basic tests used to assess thyroid function in health and disease, thyroiditis, thyroid carcinomas, and nodules of the thyroid gland. The signs, symptoms, laboratory findings, and the methods of medical and surgical therapy are discussed for each of these disorders. The supplement is not intended to provide expertise, but will provide a general and basic knowledge of thyroid disease.

Anaplastic giant and spindle-cell carcinoma of the thyroid: a different therapeutic approach

The prognosis of giant and spindle cell carcinoma of the thyroid is extremely poor. It does appear, however, that a multisciplinary approach to treatment of this aggressive cancer is more effective than a single-treatment modality. Operative ablation of gross tumor, postoperative irradiation therapy, and chemotherapy have demonstrated encouraging results. A different therapeutic approach with the addition of immunotherapy to surgical resection, postoperative irraditation, and chemotherapy is described in this case report. The preliminary result is encouraging.

Thyroid abnormalities following neck irradiation for Hodgkin's disease

Thyroid function and scans were evaluated in fifty disease-free patients 2 to 16 years after receiving neck irradiation for the treatment of Hodgkin's disease. Twenty-five of 50 patients had abnormal thyroid studies: eight were hypothyroid, two were hypothyroid and had abnormal scans, and fifteen had abnormal scans. Of the 15 patients with abnormal scans, one had an isolated elevation of TSH (thyroid stimulating hormone) and one developed exophthalmos. These data, obtained within a relatively short follow-up period, indicate that morphologic and functional abnormalities of the thyroid gland are not uncommon in patients who have received irradiation to the thyroid gland in the course of treatment for Hodgkin's disease. There is need for continuous reevaluation of the thyroid status in such patients.

Diagnostic imaging in head and neck disease: current applications of ultrasound

Diagnostic ultrasound has become firmly established as a key imaging modality in obstetrics and gynecology. Its role in abdominal and retroperitoneal disease is also well known and continues to expand. Although usage of ultrasound in the head and neck had its beginnings many years ago, the advent of newer high-resolution transducers has allowed for further investigation of diseases in this area. Of particular interest are the thyroid gland and the extracranial carotid arteries. This review summarizes the current utility of gray-scale and real-time ultrasound in evaluating head and neck disease, and discusses potential future applications of the modality.

Technical considerations in in vivo thyroid studies

Radionuclide thyroid studies, although among the oldest of clinical nuclear medicine procedures, continue to show growth and change. In the 7 years since thyroid studies were last reviewed in the Seminars, there have been marked changes in the preferred ways of doing these studies. In the areas of radiopharmaceuticals, 131I remains a useful agent in selected circumstances, but 99mTc-pertechnetate has become the agent of choice for imaging applications. Iodine-123 represents an exciting possibility for the future if problems in cost and radiopurity can be solved. New data on the dosimetry of the various agents allow for more rational choices among them, and useful guidelines can now be given for the use of these radiopharmaceuticals in problem areas such as pregnancy, nursing, and the pediatric age group. The scintillation camera with a pinhole collimator has become the instrument of choice for thyroid imaging, and the use of computers and the availability of systems for fluorescent scanning have added new possibilities for thyroid evaluation. Ancillary techniques such as ultrasound scanning also offer the possibility of improved diagnostic accuracy. These developments are reviewed in the context of clinical studies, together with a discussion of specific clinical applications and a brief look to the future.

Functioning thyroid masses in childhood and adolescence. Clinical, surgical, and pathologic correlations

Six girls, aged 5 to 15 years, presented with thyroid masses in otherwise nonpalpable thyroid glands and with normal serum thyroxine levels. Scintiscanning before and after TSH stimulation confirmed the presence of autonomous nodules in the four adolescents, of whom two had elevated T3 levels. Surgical exploration revealed adenomatous thyroid hyperplasia in three of the girls and papillary adenocarcinoma in the fourth. Scans in the other two girls revealed absence of the left lobe. One of them proved to have agenesis of the left lobe with enlargement of the right lobe because of lymphocytic thyroiditis. The other girl had an ectopic thyroid with chronic inflammation. A thorough diagnostic evaluation of single or multiple functioning thyroid masses in children and adolescents is essential in establishing the correct diagnosis. The possibility that carcinoma can occur in autonomous nodules as well as in hemiagenesis and ectopic thyroid tissue is discussed. An approach to the management of functioning thyroid masses in the pediatric age group is proposed.

The relationship of head and neck irradiation to the subsequent development of thyroid neoplasms

Individuals who have received head and neck radiation for benign conditions have a markedly increased risk of developing thyroid, salivary, and perhaps breast cancer as compared to the general population. Although the relative risk is very high, the absolute risk that any one individual who has had head or neck irradiation will develop a subsequent malignancy is low. Identification of these patients through some type of screening procedure may be beneficial in terms of prevention of subsequent morbidity and perhaps mortality from cancer, especially thyroid and salivary cancer. The risks of any detection or prophylaxis program must be carefully weighed against the probable, but unproved benefits of early detection. A major unresolved question is the natural history of microscopic thyroid carcinoma in the 25 yr-40 yr old radiation exposed population.

Thyroid cancer occurring as a late consequence of head-and-neck irradiation. Evaluation of 1056 patients

From January 1 to September 30, 1974, we examined 1056 of 5266 subjects (20.1%) who had received therapeutic irradiation primarily for infections and inflammatory disease of the upper respiratory tract at our institution during the 1940's and 1950's. The tonsillar and nasopharyngeal region was the treatment site in 85% of those examined. Palpable nodular thyroid disease was found in 16.5%, and nonpalpable lesions were detected by 99m Tc pertechnetate thyroid imaging in an additional 10.7%, for a prevalence of nodular disease of 27.2%. Operation on 71% with nodular disease revealed thyroid cancer in 33% (60 of 182). Preliminary analysis for potential risk factors suggests a correlation between radiation exposure and the presence of thyroid nodules (P less than 0.001). These findings indicate that nodular thyroid disease, both benign and malignant, continues as a major health problem for at least 35 years in exposed subjects.