The solitary thyroid nodule: diagnosis and management of malignant disease

Accuracy of fine-needle aspiration cytology in patients with radiation-induced thyroid neoplasms

BACKGROUND

Fine-needle aspiration cytology (FNAC) is useful for selecting patients with thyroid nodules for thyroidectomy. Its value in patients who have been exposed to low-dose therapeutic radiation is questionable because these patients have an increased risk of multifocal benign and malignant tumours, and thyroid cancer is common in such patients.

METHODS

Between 1960 and 1999, 171 patients with one or more thyroid nodules who had a history of exposure to radiation underwent operation; 49 of these patients had preoperative FNAC. The cytology results in these 49 patients were compared with those of an age- and sex-matched control group of patients with thyroid nodules who did not have a history of radiation exposure.

RESULTS

Of those who had been exposed to radiation, six of 20 patients with 'benign' cytology by FNAC and six of 16 patients with 'suspicious' cytology had thyroid cancer. All 13 specimens considered to be malignant on FNAC were indeed malignant. There was a higher rate of false-negative cytological examinations among patients with a history of irradiation that in those without.

CONCLUSION

FNAC of thyroid nodules in patients with a history of irradiation is not as accurate as that in non-irradiated patients, primarily because of coexisting occult thyroid cancers.

Two-dimensional electrophoretic analysis of membranous protein from human thyroid tissues and cancer cell lines

Thyroid neoplasm is the most commonly encountered neoplastic disorder in endocrine clinics. Thyroid scan, ultrasonography, and fine needle aspiration cytology (FNAC) are used as diagnostic tools to differentiate a malignant nodule from a benign lesion. There are certain limitations and pitfalls in FNAC, especially in the diagnosing of follicular tumors. The lack of characteristic findings or a specific tumor marker are the most common problems in the preoperative diagnosis of thyroid follicular carcinoma. Although serum thyroglobulin level has been used as a tumor marker for post-operative, well-differentiated thyroid cancer, the assay cannot be used for preoperative diagnosis of thyroid carcinoma. In this study, various thyroid tissues and cancer cell lines including CGTH W-1, CGTH W-3, RO 82 W-1, SW 579 cell lines were used for the investigation of tumor markers. Specific spots were identified in the area near the 60 kDa molecular mass protein and isoelectric point (pI) 5.9 of the CGTH W-1 cell line. These spots could not be found in the papillary or anaplastic thyroid cancer cell lines. Another spot with a molecular weight of about 9.8 kDa with a low pI of 4.8 was present in the CGTH W-1 and RO 82 W-1 cell lines. This spot appeared to be a tumor marker of follicular cancer cells. This spot could not be found in the papillary and anaplastic cancer cell lines and other benign thyroid tissues. Specific proteins that were identified in this study may be useful as tumor markers for follicular thyroid carcinoma.

Comparison of the results of diagnosis and treatment between solid and cystic well-differentiated thyroid carcinomas

We assessed the accuracy of ultrasonography and fine-needle aspiration cytology (FNAC) in diagnosing cystic thyroid cancer and compared the results with solid thyroid cancer patients. We also compared the results of treatment between these patient groups. We retrospectively reviewed 1013 thyroid cancer patients who received treatment at Chang Gung Memorial Hospital. For this study, 910 cases of papillary or follicular thyroid carcinomas were considered eligible. Of these, 682 patients received preoperative high-resolution ultrasonographic and FNAC examinations. The nodules of 583 (85.5%) patients were diagnosed as solid masses, 80 (11.7%) as mixed masses, and 19 (2.8%) as cystic masses. Of the 19 patients with cystic thyroid carcinoma, only 4 papillary thyroid carcinomas were diagnosed by ultrasonography with FNAC as malignant before operation. Six patients presented as occult thyroid carcinomas with the tumor size less than 1 cm. Despite the low rate of accurate diagnosis for the cystic malignancy, clinical staging and the survival rates were not statistically different when they were compared with the other groups. In conclusion, low diagnostic rates were observed in well-differentiated thyroid cancer with prospective ultrasound-guided FNA when lesions were cystic or in mixed lesions. If the solid portion of the cystic masses is aspirated under ultrasound-guided FNA and cytology is performed after the centrifugation of the aspirated fluid, diagnostic accuracy may be improved.

Thyroid ultrasonography with fine-needle aspiration cytology for the diagnosis of thyroid cancer

This series retrospectively reviewed 3657 patients who received thyroid ultrasonography with fine-needle aspiration cytological (FNAC) examinations at Chang Gung Memorial Hospital during the period from January 1, 1993 to December 31, 1993. Thyroid ultrasonography studies were performed using a real-time ultrasonographic machine with a 10 MHz transducer. The aspirates were air dried and stained by the Romanowsky-based Liu method. Three hundred seventy-eight cases (10.3%) received surgical treatment after the ultrasonographic and FNAC examinations. Benign lesions were diagnosed in 269 patients. Thyroid malignancy was confirmed histopathologically in 109 cases including 76 papillary thyroid carcinomas, 17 follicular carcinomas, 5 medullary thyroid carcinomas, 3 anaplastic carcinomas, 3 Hürthle cell carcinomas, and 3 lymphomas. Another 2 cases were metastatic cancer to thyroid. The results demonstrated that 28.8% of the surgically treated patients had histopathologically proven malignancies. The incidence of thyroid malignancy was 2.98% in this study. The sensitivity of the cytological diagnosis was 79.80% and the specificity was 98.66%. The positive predictive value was 96.34%. Negative predictive value was 91.70%. The false negative index was 20.20%. The diagnostic accuracy was 92.89%. Thyroid ultrasonography with the FNAC can provide high specificity and sensitivity in differentiating malignant lesions from benign.

Thyroid cancer treated in Chang Gung Memorial Hospital (northern Taiwan) during the period 1979-1992: clinical presentation, pathological finding, analysis of prognostic variables, and results of treatment

This study is a retrospective analysis of 248 thyroid cancer patients who received their primary treatment in the Chang Gung Memorial Hospital during the period January 1979 to December 1992. Among these cases, there were 173 papillary thyroid cancers (69.8%), 52 cases of follicular thyroid cancer (21%), 7 cases of medullary thyroid cancer (2.8%), and 16 cases of anaplastic thyroid cancer (6.5%). The subjects included 184 female patients with a mean age of 40.7 +/- 14.3 years and 64 males patients with a mean age of 49.2 +/- 14.3 years. Most of the cases had a nearly total thyroidectomy after the diagnosis was confirmed by frozen section during the operation. During the follow-up period, 19 (8.2%) patients diagnosed with well-differentiated thyroid cancer died of thyroid cancer in contrast to 12 patients (75%) with anaplastic thyroid cancer. The 1-year Greenwood survival probabilities after the disease is diagnosed in papillary, follicular, and anaplastic thyroid cancer are 0.98, 0.86, and 0.25, respectively. For the analysis of prognostic variables in well-differentiated thyroid cancer patients, 16 factors were entered for univariate and multivariate analysis. Using a log-rank univariate analysis, survival was significantly associated with the cell type of the primary tumor, age, clinical staging, postoperative 131I pattern, tumor size, postoperative thyroglobulin (Tg) level and postoperative x-ray results. In the Cox multivariate regression analysis the combination factors that gave the best prognostic value were the association of x-ray finding (P = .004), age (P = .017), and Tg level (P = 0.19). In conclusion, thyroid cancer is not an unusual disease in Taiwan. As previously reported anaplastic thyroid cancer has a poor prognosis. In this limited period of follow-up study, the patients' age with postoperative first positive x-ray finding and Tg level may provide the prognostic factors for patients with well-differentiated thyroid cancer.

Occult distant metastases of well-differentiated thyroid carcinoma

BACKGROUND

The tendency of well-differentiated thyroid carcinoma to remain localized and its slow progression have supported the belief that this disease behaves as a low-grade malignancy. Consequently, a conservative approach in the management of the well-differentiated thyroid carcinoma has existed during the years. Occult distant metastases of thyroid cancer is an occasional finding considered of ominous significance.

METHODS

In a retrospective study, we reviewed the records of 187 adult patients with well-differentiated thyroid carcinoma treated by total thyroidectomy. These cases were found among 1,240 thyroidectomies performed in our department between 1982 and 1993. Occult distant skeletal and lung metastases disclosed by total body 131I scans, after total thyroidectomy, were present at the time of initial treatment in 11 patients (11/187). This group included 9 women and 2 men ranging in age from 36 to 70 years, with a mean age of 47 years. Seven patients had papillary carcinoma, whereas follicular malignancy was found in four. Review of the surgical specimens showed total involvement of the gland in 5 cases, with extracapsular tumoral spread in 3 patients. Multicentric disease was present in 6 specimens. Patient follow-up revealed a mortality rate of 64% (7/11) during the first 3 post-operative years.

CONCLUSIONS

Analysis of this population confirms that well-differentiated thyroid carcinoma with distant metastases is an aggressive disease with lethal consequence. Early detection and therapy of occult distant metastases present at the time of initial treatment is possible only after total thyroid ablation, because otherwise the radioactive iodine is trapped by the gland's remnants.

Preoperative diagnostic tests for operable thyroid disease

Although the availability and acceptance of fine-needle aspiration biopsy (FNAB) of thyroid nodules has increased, many physicians still use thyroid scintigraphy for distinguishing benign from malignant lesions. We evaluated these diagnostic tests in 350 patients who had thyroid surgery in our institution between 1977 and 1990. Histologic confirmation of FNAB was obtained in 265 patients. In the group of patients having surgery, 247 thyroid scintigraphies were performed. Our patients were divided into two groups (1977-1986 and 1986-1990). The first group comprised 173 patients with 173 FNABs and 126 scintigrams. The second group consisted of 177 patients having 92 FNABs and 121 scintigrams. Results of scintigrams were analyzed in the second group only. In 5 out of 120 cases where the FNAB result was "benign or probably benign" the lesion appeared to be malignant postoperatively. If the FNAB result was "malignant or probably malignant" (n = 83) the pathology report confirmed a malignancy in 68 cases (81.9%). In 56 instances of all 265 FNABs the cytology report was not conclusive ("uncertain"); in 21.4% of these cases a malignancy was found postoperatively. An FNAB-result "(probably) malignant" had a positive predictive value of 0.819 while the negative predictive value of a result "(probably) benign" is 0.950. An "uncertain" result does not take away our concern so this result should have the same consequences as those of a result "(probably) malignant". In that case, FNAB-sensitivity is 93.0% and specificity 66.1%. Eighty-five of the last 116 scintigraphies showed a solitary node. Eleven of these nodes were hot while 74 were cold.(ABSTRACT TRUNCATED AT 250 WORDS)

Secondary malignancy of the thyroid gland: a case report and review of the literature

Metastatic cancer to the thyroid gland is uncommon. In this report we describe a patient with a malignant fibrous histiocytoma that metastasized to the thyroid, possibly to a preexisting thyroid nodule. A review of the literature reveals that breast and lung carcinoma are the most frequently identified sources of secondary thyroid carcinoma found at autopsy, while renal carcinoma comprises over 50% of secondary thyroid malignancies discovered clinically. A number of authors suggest that preexisting thyroid disease (i.e., multinodular goiter and thyroid nodules) may provide a nidus for metastases to the thyroid gland.

Thyroid carcinoma presenting as a regional neck mass

During 1978-1988, we treated 197 patients with thyroid carcinoma. Twenty-seven patients (14.0%) presented with a regional cervical mass and a clinically normal thyroid gland on initial evaluation. Excisional biopsy proved the diagnosis of metastatic thyroid carcinoma in every patient. Subsequent thyroid scans were 42% sensitive. Only 3 patients underwent fine-needle aspirations; none showed evidence of malignant cells. Review of surgical specimens showed total involvement of the gland in 13 of 17 cases, with extracapsular spread of tumor in 3 patients. Multicentric disease was present in all but 2 neck specimens. Patient follow-up from 1 month to 10 years revealed an 11.5% recurrence rate. The results in this group of patients is compared to the larger group of thyroid carcinoma patients, where three recurrences were found in 170 patients presenting with a clinically palpable mass in the thyroid gland. Analysis of our population comparing the subgroup with the larger series of thyroid carcinoma patients suggests that thyroid carcinoma presenting as a regional neck mass is a more aggressive disease.

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.