Case-control study of thyroid cancer in Northern Italy: attributable risk.
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BACKGROUND: The percentage of thyroid cancer cases attributable to specific risk factors can be calculated to focus preventive strategies. The per cent population attributable risks (PAR) for thyroid cancer were estimated in relation to history of benign thyroid diseases, history of radiotherapy, residence in endemic goitre areas and selected indicators of a poor diet, using data from a case-control study conducted between 1986 and 1992 in Northern Italy. METHODS: Cases were 399 histologically confirmed incident thyroid cancers and controls were 617 patients, admitted to hospital for a wide range of acute, non-neoplastic, non-hormone-related diseases. The PAR were computed on the basis of multivariate odds ratios (OR) and on the distribution of risk exposure among cases, assuming they are representative of the general population of cases. RESULTS: A history of benign thyroid disease accounted for 18.9% of cases, radiotherapy for 1.2%, residence for > or =20 years in endemic goitre areas for 2.4% of cases, and their combination for 21.7% of thyroid cancer cases; selected indicators of a poor diet accounted for 40.9% of thyroid cancer cases in this population. The combination of all factors considered explained over 57% of thyroid cancer cases in both sexes. The estimates for thyroid-related conditions were higher in women than men, whereas the opposite was true for dietary indicators. The overall PAR were somewhat higher in people aged > or =45 years (63.8%) than in younger subjects, and for follicular (69.1%) rather than papillary (53.7%) cancers. CONCLUSIONS: Exposure to a few simply identified and potentially modifiable risk factors or indicators (benign thyroid disease, residence in endemic goitre area and a poor diet) explained about 60% of thyroid cancer cases in this Italian population, indicating the theoretical scope for prevention. (+info)
Mixed medullary-follicular thyroid carcinoma. Molecular evidence for a dual origin of tumor components.
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Mixed medullary-follicular carcinomas (MMFCs) are tumors of the thyroid that display morphological and immunohistochemical features of both medullary and follicular neoplasms. The histogenetic origin and possible molecular mechanisms leading to MMFCs are still unclear. To address these questions, we have isolated the two histological components of 12 MMFCs by (laser-based) microdissection, analyzed them for mutations in the RET proto-oncogene and allelic losses of nine loci on six chromosomes, and studied the clonal composition of MMFCs in female patients. Our results provide strong evidence that the follicular and medullary components in MMFCs are not derived from a single progenitor cell, because the seven tumors amenable for analysis consistently exhibited a different pattern of mutations, allelic losses, and clonal composition. We also demonstrate that follicular structures in MMFCs are often oligo/polyclonal and more frequently exhibit hyperplastic than neoplastic histological features, indicating that at least a subset of MMFCs are composed of a medullary thyroid carcinoma containing hyperplastic follicles. (+info)
Reproductive and hormonal risk factors for thyroid cancer in Los Angeles County females.
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We conducted an individually matched case-control study (292 pairs) of female thyroid cancer patients to examine the role of reproductive history and exogenous hormones in this disease. Radiation treatment to the head or neck [28 cases and 2 controls exposed; odds ratio (OR), 14.0; 95% confidence interval (CI), 3.5-121.3] and certain benign thyroid diseases (including adolescent thyroid enlargement, goiter, and nodules or tumors) were strongly associated with thyroid cancer. Irregular menstruation increased risk (OR, 1.8; 95% CI, 0.9-3.7). Age at menarche and pregnancy history were not related to disease. Women with natural menopause and hysterectomized women without oophorectomy had no increase in risk, but disease risk was elevated in women with bilateral oophorectomy (OR, 6.5; 95% CI, 1.1-38.1). In general, use of oral contraceptives and other exogenous estrogens was not associated with thyroid cancer. However, risk increased with number of pregnancies in women using lactation suppressants (P = 0.03) and decreased with duration of breastfeeding (P = 0.04). These data provide only limited support for the hypothesis that reproductive and hormonal exposures are responsible for the marked excess of thyroid cancer risk in adult females. (+info)
Follicular carcinoma in a functioning struma ovarii.
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We describe a case of follicular carcinoma in a functioning struma ovarii, which presented as an ovarian mass in a patient who had undergone a near-total thyroidectomy for a benign lesion. She underwent bilateral salpingo-oophorectomy and received radiotherapy and L-thyroxine treatment with no evidence of metastases in 4 years follow-up. (+info)
Encapsulated follicular variant of papillary thyroid carcinoma with bone metastases.
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Although true follicular thyroid carcinoma is known to metastasize via the bloodstream and give rise to bone and lung metastases, such a pattern of spread is rare in papillary thyroid carcinoma. The follicular variant of papillary thyroid carcinoma (FVPTC) is believed to behave in a clinical manner similar to usual or classical papillary cancer and to follow a similar indolent course. There have been a few reports of "aggressive" FVPTC wherein follicular patterned tumors with nuclear features of papillary carcinoma have metastasized hematogenously; these neoplasms have been diffusely invasive or multicentric in the thyroid. We report five cases of FVPTC, which were encapsulated and simulated grossly and microscopically follicular adenomas. In two of these, the primary was discovered after clinical presentation of bone metastases. In three others, bony metastases (without other nonosseous metastases) arose 7 to 17 years after thyroid lobectomy for lesions initially diagnosed as follicular adenoma In retrospect, these three encapsulated lesions had vascular invasion. We wish to bring attention to these innocuous-appearing lesions, which, although sharing nuclear features of papillary cancer, behave clinically in an unexpectedly malignant fashion. (+info)
Immunohistochemical diagnosis of papillary thyroid carcinoma.
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In thyroid, the diagnosis of papillary carcinoma (PC) is based on nuclear features; however, identification of these features is inconsistent and controversial. Proposed markers of PC include HBME-1, specific cytokeratins (CK) such as CK19, and ret, the latter reflecting a ret/PTC rearrangement. We applied immunohistochemical stains to determine the diagnostic accuracy of these three markers. Formalin-fixed, paraffin-embedded tissue from 232 surgically resected thyroid nodules included 40 hyperplastic nodules (NH), 35 follicular adenomas (FA), 138 papillary carcinomas (PC; 54 classical papillary tumors and 84 follicular variant papillary carcinomas [FVPC]), 4 follicular carcinomas (FC), 6 insular carcinomas (IC), 7 Hurthle cell carcinomas (HCC), and 2 anaplastic carcinomas (AC). HBME-1 and ret were negative in all NH and FA; some of these exhibited focal CK19 reactivity in areas of degeneration. Half of the FC and AC exhibited HBME-1 staining but no positivity for CK19 or ret. In PC, 20% of cases stained for all three markers. Classical PC had the highest positivity with staining for HBME-1 in 70%, CK19 in 80%, and ret in 78%. FVPC were positive for HBME-1 in 45%, for CK19 in 57%, and for ret in 63%; only 7 FVPC were negative for all three markers. The six IC exhibited 67% staining for HBME-1 and 50% positivity for CK19 and ret. The seven HCC had 29% positivity for HBME-1 and CK19, and 57% positivity for ret. This panel of three immunohistochemical markers provides a useful means of diagnosing PC. Focal CK19 staining may be found in benign lesions, but diffuse positivity is characteristic of PC. HBME-1 positivity indicates malignancy but not papillary differentiation. Only rarely are all three markers negative in PC; this panel therefore provides an objective and reproducible tool for the analysis of difficult thyroid nodules. (+info)
Thyroglobulin immunoreactivity in lymph node histiocytes: a potential diagnostic pitfall.
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AIMS: Strong thyroglobulin immunoreactivity within sinus histiocytes in a lymph node draining a papillary thyroid carcinoma was observed in a recent case. This prompted the investigation of whether thyroglobulin immunoreactivity is common in regional lymph nodes in cases of thyroid malignancy. METHODS: Eighty seven lymph nodes were studied from 21 cases of thyroid malignancy. These comprised papillary carcinoma (n = 12), follicular carcinoma (n = 4), medullary carcinoma (n = 3), and one case each of squamous and anaplastic carcinoma. Eleven cervical lymph nodes from patients with no evidence of thyroid disease were included as controls. Sections were stained with a monoclonal antibody against thyroglobulin. RESULTS: In the cases of thyroid malignancy, 32 of 87 lymph nodes showed positive staining for thyroglobulin of histiocytes within the subcapsular and medullary sinuses. In an additional four cases, there was positive staining of lymph within lymphatic channels. Positivity was present in at least one node in 15 of 21 cases. There was no positivity in the control cases. There was no correlation between the size of the primary tumour and the presence of thyroglobulin positivity. CONCLUSIONS: Positive staining with antithyroglobulin occurs not uncommonly in sinus histiocytes in lymph nodes draining thyroid tumours. This positivity could be the result of the destruction of normal thyroid follicles, with the release of thyroglobulin, which is taken up by histiocytes, which subsequently drain to local lymph nodes. Pathologists should be aware of this phenomenon and should be careful not to interpret this as metastatic tumour. (+info)
Fine needle aspiration biopsy of thyroid nodules.
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BACKGROUND: Fine needle aspiration biopsy (FNA) is a routine diagnostic technique for evaluating thyroid nodules. Many reports in adults consider that FNA is superior to thyroid ultrasonography (USG) and radionuclide scanning (RS). Only five studies have been published on FNA of childhood thyroid nodules. AIMS: To investigate the reliability of FNA in the evaluation and management of thyroid nodules, and compare the results of FNA, USG, and RS with regard to final histopathological diagnosis. METHODS: FNA was performed in 46 children with thyroid nodules after USG and RS examination. We investigated the sensitivity, specificity, accuracy, and positive and negative predictive values of USG, RS, and FNA in their management. RESULTS: Six patients who had malignant or suspicious cells on FNA examination underwent immediate surgery. The other 40 patients received medical treatment according to their hormonal status. Fifteen of these nodules either disappeared or decreased in number and/or size. Surgery was performed in 25 patients who did not respond to therapy. Statistical analysis revealed sensitivity, specificity, accuracy, and positive and negative predictive values respectively as follows: 60%, 59%, 59%, 15%, and 92% for USG; 30%, 42%, 39%, 12%, and 68% for SC; 100%, 95%, 95%, 67%, and 100% for FNAB. CONCLUSION: FNAB is as reliable in children as in adults for definitive diagnosis of thyroid nodules. Using this technique avoids unnecessary thyroid surgery in children. (+info)