The solitary thyroid nodule

Positron emission tomography-positive thyroid nodules: rate of malignancy and histological features

BACKGROUND

Thyroid nodules may be incidentally detected on (18) F-FDG-positron emission tomography (PET) scans. Previous reports suggest a high incidence of malignancy in FDG-avid nodules. The aims of this study were to examine the incidence of malignancy in a large cohort and to report on the histological features. The findings suggest that poor prognostic histologic features are often associated with FDG-avid thyroid nodules and this may have clinical implications.

METHODS

A retrospective review of prospectively collected data was conducted. A database containing all patients who underwent PET scanning at a single tertiary referral centre from January 2006 to January 2013 was searched to identify those with incidental PET-positive thyroid nodules. Patients with known preexisting thyroid disease were excluded from analysis. The demographics, fine-needle aspiration (FNA) biopsy result and operative histopathology were analysed.

RESULTS

A total of 27 851 FDG-PET scans were performed of which 221 found incidental PET-positive thyroid nodules (incidence 0.8%). Fifty-three patients went on to have further investigation and 21 of these were found to have malignant disease (incidence 39.6%). Histopathological examination of 12 malignant nodules revealed an expected rate of poor prognostic features, including poorly differentiated subtype (8.3%), lymphovascular invasion (16.7%), perineural invasion (8.3%) and extrathyroid extension (33.3%).

CONCLUSION

Our data indicate that PET-positive thyroid nodules are associated with a high incidence of malignancy. This finding provides strong support for further investigation including FNA biopsy in all surgically suitable patients.

Estimated dietary intake of thiocyanate from Brassicaceae family in Korean diet

Glucosinolate, sulfur-containing organic anions bonded to glucose, is found in plants including the family of Brassicaceae. Glucosinolate is hydrolyzed by myrosinase and produces various by-products that possess biological activities. Among the decomposed products, thiocyanate is known for its adverse effects on thyroid metabolism due to competition with iodine. This is of concern in that Korean dietary habits consist of consumption of large amounts of Brassicaceae vegetables such as cabbage and radishes, which may be correlated with high incidence of thyroid dysfunction. Thus, quantification of thiocyanate in Brassicaceae vegetables was performed by hydrolysis and spectrophotometrical detection. Average daily intake of Brassicaceae vegetables was obtained from the Third Korea National Health and Nutrition Examination Survey (KNHANES III), 2005-Nutrition Survey and from The Vegetable Production Statistics, 2007. Average daily intake of thiocyanate through Brassicaceae vegetables in Korea was estimated to be 16.3 micromol SCN(-)/d/person. When this was compared to published animal studies, average thiocyanate intake per person was lower than doses required to produce adverse effects. However, further studies may be warranted to ensure safety with sufficient margins of safety.

Imaging the thyroid

Thyroid imaging has historically relied heavily on scintigraphy, although, not surprisingly in view of the superficial position of the gland, ultrasound has assumed an increasingly prominent role in recent years. The other cross-sectional imaging modalities can also be useful, and the emergence of new radiopharmaceuticals and the increasingly central role of fine needle aspiration cytology have further added to the range of diagnostic techniques available. This review attempts to summarize the current state of knowledge, and makes some suggestions for the most efficient use of imaging resources in the investigation of thyroid disease.

The epidemiology of thyroid disease and implications for screening

The burden of thyroid disease in the general population is enormous. As many as 50% of people in the community have microscopic nodules, 3.5% have occult papillary carcinoma, 15% have palpable goiters, 10% demonstrate an abnormal thyroid-stimulating hormone level, and 5% of women have overt hypothyroidism or hyperthyroidism. Despite this high prevalence of thyroid disease, screening for these disorders is not recommended by any major health agency. This article explores the epidemiologic issues surrounding this complex problem by analyzing prevalence, incidence, and mortality data from a worldwide variety of sources.

Solitary thyroid nodule: a prospective evaluation of nuclear scanning and ultrasonography

The aim of this study was to assess prospectively the value of thyroid nuclear scans and ultrasound examination in the preoperative investigation of patients with a solitary thyroid nodule. Total thyroid lobectomy for a solitary thyroid nodule was performed in 68 cases. Each patient had a thyroid isotope scan (except two women who were pregnant) and thyroid ultrasound examination. There were 10 (15 per cent) malignant nodules, 11 (16 per cent) benign neoplastic nodules and 47 (69 per cent) benign non-neoplastic nodules. All of the patients with malignant nodules who were scanned had a solitary cold nodule on thyroid scan, as did 40 (69 per cent) of those with benign solitary nodules. Ultrasound examination of the thyroid suggested correctly that one of 16 (6 per cent) cystic lesions, four of 16 (25 per cent) complex solid-cystic lesions and three of 18 (17 per cent) of solid lesions were malignant. One lesion reported as multinodular on ultrasonography and one reported as normal also turned out to be malignant. Thyroid isotope scans and ultrasound do not accurately differentiate between benign and malignant conditions and their routine use in the investigation of a solitary thyroid nodule should be abandoned.

Management of the thyroid nodule

The approach to the patient with a palpable solitary thyroid nodule remains controversial. In the rare patient with signs and symptoms suggestive of malignancy, the course of action is reasonably established. However, the patient with an asymptomatic solitary thyroid nodule presents a dilemma. The therapeutic alternatives range from suppressive medical therapy with serial examinations to surgical excision; therefore, to obviate unnecessary surgery, several diagnostic techniques and approaches have evolved which attempt to predict the presence of malignancy. A multitude of articles reflects the widespread disagreement among physicians regarding these diagnostic approaches. Thus, many questions still remain as to the proper management of patients with solitary nodules. The issue is further confounded by problems in assimilating and practically applying the results of the various studies, which often differ in their results. In this report, data regarding the prevalence of the solitary thyroid nodule are reviewed, and the clinical significance of the solitary thyroid nodule is discussed. The problem of management is examined in terms of the various diagnostic approaches to the solitary thyroid nodule: history and physical examination, laboratory tests, ultrasonography, thyroid suppressive therapy, scanning techniques, and fine-needle aspiration. The efficacy of each technique is critically evaluated with an emphasis upon the ability to distinguish benign from malignant disease. The overall aim of this report is to establish a reasonable diagnostic approach to the asymptomatic patient with the solitary palpable thyroid nodule, based upon a critical review of the literature.

Management of thyroid nodules

This review describes the frequency of solitary thyroid nodules and their relationship to thyroid cancer. The importance of selecting patients appropriately for surgical excision is stressed. The factors predisposing to nodule formation and to a nodule being malignant are reviewed with emphasis that prior radiation exposure does not appear to increase the likelihood that a given nodule harbors a malignancy. In considering the laboratory evaluation of thyroid nodules, the limitations of isotope scans and ultrasonography are noted. Fine needle aspiration biopsy is described as revolutionizing the management of thyroid nodules and decreasing unnecessary operations. In the context of the natural history of differentiated thyroid cancer, the application of a decision analysis model to management options is described in some detail, and a cost-effective management regimen is recommended with fine needle aspiration biopsy as the initial procedure.

Solitary thyroid nodule: diagnosis and management

Thyroid nodules are common. Most are benign lesions since clinically important thyroid carcinoma is a relatively rare disease. The most sensitive and specific test for the diagnosis of thyroid cancer is fine-needle aspiration biopsy, but its diagnostic accuracy depends upon whether or not one excises all suspicious nodules, thus including them as correctly diagnosed. Nevertheless, fine-needle aspiration biopsy is the most sensitive, specific, and cost-effective test for thyroid cancer. Therapy depends upon the cause of the thyroid nodule.

Pediatric endocrine surgery

The pediatric surgeon is in a unique position to understand endocrine surgery and, therefore, is expected to develop considerable expertise in this area. In recent years numerous advances and changes have occurred in pediatric endocrine surgery that have led to greater understanding of the disease processes and syndromes and the development of new diagnostic techniques and surgical approaches.

Surgery for thyroid carcinoma

The cases of thyroid carcinoma treated at this hospital during the period 1948 to 1981 were reviewed retrospectively. Nine hundred eighty-six patients with thyroid nodules were operated on. One hundred fifty-two were thyroid carcinoma (59 papillary, 36 mixed papillary-follicular, 30 follicular, 20 anaplastic, 5 medullary, and 2 Hurthle cell tumors). There was a 92% follow-up for a mean of 10 years. In the last decade, patients presented at a younger age, the female predominance was diminished, and 15% had had previous neck irradiation. Surgery consisted of total (27) or subtotal thyroidectomy (89), lobectomy or nodulectomy (24), and biopsy (12). Total thyroidectomy had an incidence of postoperative complications that was 20 times higher than that with partial thyroidectomy (P less than 0.001). Disease-related death, recurrence, and survivor status were discussed. There was no significant difference between total versus subtotal thyroidectomy. This study reaffirms the usefulness of subtotal resection and the avoidance of morbidity of more radical total thyroidectomy surgery.

The solitary thyroid nodule: diagnosis and management of malignant disease

While few solitary thyroid nodules are carcinomatous, it is essential to identify and preferentially select those that are for surgery. Clinical, biochemical, serologic, radiographic, scintigraphic, sonographic, biopsy, and even therapeutic evaluation may be necessary to choose those patients with the greatest probability of malignancy. The benefits and limitations of each diagnostic modality are discussed, and the importance of fine-needle aspiration is stressed. After the operative confirmation of malignancy, the prognosis in any given case depends on 1) the histologic type of the neoplasm, 2) its size and extent, 3) the presence of angioinvasiveness, 4) the tendency toward multicentricity of the lesion, 5) the age and sex of the patient, and 6) whether distant metastases are present. These factors influence the extent of surgery required for well-differentiated carcinomas. Meticulous dissection and preservation of the recurrent laryngeal nerves and the parathyroid glands along with their blood supply are important if total thyroidectomy for papillary carcinoma is to be employed with an acceptable operative morbidity to optimize survival. The value of the adjunctive use of thyroid hormone and radioactive iodine is also discussed. Finally, the clinical behaviors and treatments of undifferentiated carcinomas, sarcomas, lymphomas, and neoplasms metastatic to the thyroid gland are reviewed.

Surgical intervention in chronic (Hashimoto's) thyroiditis

The incidence of chronic (Hashimoto's) thyroiditis in surgical specimens is relatively high, i.e., 13% in collected studies, for a disease with clinical and laboratory characteristics that are sufficiently specific, that thyroidectomy should rarely be required for diagnosis or treatment. This incidence is presumably related to the difficulty in distinguishing between thyroiditis and a thyroid neoplasm. Experience with 260 thyroidectomies at the North Carolina Memorial Hospital performed between 1875 and 1980 for a dominant thyroid mass was reviewed to determine the reliability of criteria for diagnosis and the indications for surgical treatment. Using the criteria of clinical findings, complemented by laboratory studies, e.g., free thyroxine index, thyroid autoantibodies, TSH level, thyroid scan, in addition to the judicious use of the cutting (core) needle biopsy procedure, the incidence of Hashimoto's thyroiditis in this series was 3% and cancer-27%. Four patients had Hashimoto's thyroiditis coincidental to another disease for which thyroidectomy was performed. In seven patients Hashimoto's thyroiditis alone constituted the indications for operation. The indications for operation in these patients were: autonomous function with mild hyperthyroidism (2 patients); associated cold nodule (2 patients); thyromegaly unresponsive to suppressive therapy (2 patients); and rapidly enlarging mass simulating a neoplasm (1 patient). Only one of 71 patients with well differentiated carcinoma had Hashimoto's thyroiditis. One patient with Hashimoto's thyroiditis had associated lymphoma. In most patients, Hashimoto's thyroiditis can be identified using appropriate clinical and laboratory criteria without resorting to thyroidectomy to differentiate between thyroiditis and a neoplasm. Operations are indicated in patients with suspected or established chronic thyroiditis for: 1) the presence of a dominant mass with incomplete regression on suppressive therapy. 2) Progression of thyromegaly despite suppressive therapy. 3) Historic or physical findings suggest a malignancy, e.g., irradiation, multiple endocrine adenomatosis (MEA) syndrome, nerve paralysis, pain, tracheal compression, stipple calcification and cervical lymph node enlargement. 4) Indeterminant findings on cutting needle biopsy, e.g., lymphoma versus thyroiditis. Rarely, an operation is required for an oppressive goiter or associated hyperthyroidism.

Management of thyroid nodules. I: History and physical examination, blood tests, X-ray tests, and ultrasonography

The approach to the management of the thyroid nodule remains controversial. Confusion exists because virtually any thyroidal disease can present as a clinically solitary nodule which means there is no uniformity regarding natural history, incidence, prevalence, epidemiology, and pathophysiology.. The variety of definitions of thyroid nodules and thyroid carcinoma and the different modes of study selection and individual bias add to the confusion. Diagnostic approaches have not yielded a completely reliable technique to differentiate benign from malignant thyroidal disease. A history of neck irradiation of cervical lymphadenopathy significantly increases the chance of thyroid malignancy, but other parameters of the history or physical examination as well as blood tests are unreliable. Ultrasound displays anatomic but not histologic features. X-ray techniques (plain films, computed tomographic scans, xeroradiography, chest x-ray, barium swallow, lymphography, and angiography) have been used to visualize thyroid nodules, with some techniques proving more useful than others.

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.

Grey scale ultrasonic examination of the thyroid gland

High resolution grey scale echography is an accurate, non-invasive means of investigating thyroid lesions. The structural information which it provides complements that of the functional status of the gland obtained from radionuclide scanning. The principles and practice of the technique are discussed and clinical examples are presented.

Prediction of malignancy in solitary thyroid nodules in a country with endemic goiter

From January 1962 through October 1975, 455 patients with single thyroid nodules were operated on at King Paul Hospital. Malignancy was proved in forty-three patients. The overall incidence of carcinoma was 9.5 per cent. A higher incidence of cancer was found in patients less than ten years of age (40 per cent), between eleven and twenty years of age (20 per cent), and more than sixty-one years of age (17.4 per cent). Malignant nodules were more frequent in males (17.5 per cent) than in females (8.3 per cent). Radioactive iodine scanning does not distinguish benign from malignant nodule. Solitary thyroid nodules require operative excision supplemented with replacement therapy.

The malignant "cold" nodule of the thyroid

From 1958 to 1976, 910 patients with cold nodules of the thyroid underwent thyroid surgery (714 females, 196 males). Thyroid carcinoma was present in 202 patients (22.2 per cent) (149 females, 20.9 per cent; 53 males, 27 per cent). Rate of malignancy in an age group was greatest in patients older than seventy years (19 of 47 patients, 40.4 per cent) followed by patients twenty-one to thirty years of age (37 of 125 patients, 29.6 per cent); 90 per cent of all patients were from twenty-one to seventy years of age. Blacks had a lower rate of thyroid carcinoma than Caucasians. Data from the Cancer Surveillance Group also showed age-adjusted incidence rates in blacks in Los Angeles County to be lower than that of Caucasians.

Evaluation of dominant thyroid masses

Controversy exists concerning the management of solitary thryoid nodules because of conflicting information converning the high clinical incidence of thyroid nodules, the varying incidence of cancer reported in those surgically excised and the infrequency of death from thyroid cancer. During the past several years, a plan for evaluating patients with dominant thyroid masses has evolved. The objective is to avoid unnecessary operations by identifying patients with a high risk of cancer. The criteria which are used are the age and sex of the patient, the duration of the mass, 125I or 99mTc scans, 75Selenomethionine scans, B-mode ultrasonography and the response of the mass to suppressive therapy. This is a report of the findings in 222 patients who have been studied employing this approach. Thirty per cent of the patients were operated upon. Forty per cent had neoplasms (well differentiated cancer--28.8%, adenoma--12.1%), 47.0%--nodular goiter, 6.1% cysts, and 6.1% chronic thyroiditis. The incidence of cancer in the 222 patients was 8.6% and adenoma 3.6%. Patients at greatest risk of having cancer are those with solid nonfunctioning nodules which fail to regress with suppressive therapy. This study indicates that the approach described above is effective in selecting for surgical excision those individuals at greatest risk of having thyroid cancer.

The single palpable thyroid nodule: evaluation by 99mTc-pertechnetate imaging

The role of 99mTc-pertechnetate thyroid imaging in the preoperative assessment of patients with single palpable thyroid nodules was evaluated. The frequency of cancer in hypofunctional nodules was similar to that found in previous studies with 131I. The 99mTc-pertechnetate image allowed a reliable separation of pathologically uninodular thyroids from those that were multinodular, and demonstrated multiple thyroid lesions that had not been detected by physical examination in over one-third of the cases. The frequency of cancer in thyroids containing a solitary or dominant hypofunctional nodule was higher (17%) than that in thyroids with a multinodular scan appearance (less than 5%).