Differentiated thyroid carcinoma, intermediate type: a new tumor entity with features of follicular and parafollicular cell carcinoma

Synchronous occurrence of medullary and papillary thyroid cancer and survival rates

PURPOSE

Concurrence of medullary and papillary thyroid carcinoma (MTC and PTC) represents less than 1% of all thyroid malignancies. We aimed to reveal the demographic and clinical characteristics of this rare pathology and to evaluate the effect of the same or contralateral lobular localization of these two malignancies in clinical and laboratory features. Evaluation of progression-free survival (PFS) in current pathology is one of the important features of our study.

METHODS

All patients diagnosed with simultaneous MTC and PTC after thyroidectomy were evaluated retrospectively. Data on the following variables were recorded: age, gender, tumor localization (ipsilateral lobe located MTC and PTC-Group I, contralateral lobe located MTC and PTC-Group II), tumor size, cervical lymph node metastasis, distant metastasis, tumor stage, postoperative basal calcitonin, carcinoembryonic antigen, thyroglobulin (Tg), and anti-Tg values. In all our cases, since MTC progressed before PTC, progression was accepted as serum calcitonin values exceeded 150 pg/mL.

RESULTS

Groups were formed as follows: Group I, four cases where MTC and PTC were localized in different foci in the same lobe; Group II, nine cases where they were localized in different lobes. There was only one case in which two tumors were located in the same focus. The case with dual differentiation was included in Group I (35. 7%). When the PFS of the two groups were compared, no statistically significant difference was found ( P = 0.87).

CONCLUSIONS

As a result of this analysis, the location of the simultaneously detected PTC in the same or different lobes with the MTC does not make a significant difference in clinical and laboratory features.

Oncocytic poorly differentiated (insular) thyroid carcinoma mimicking metastatic adenocarcinoma. A case report and review of the literature

We report the cytohistologic and immunohistochemical findings of an oncocytic variant of poorly differentiated thyroid carcinoma in a 76-year old man with a prior history of prostatic adenocarcinoma. The man complained of a palpable nodule in the right thyroid lobe and cervical lymph node. Fine-needle aspiration (FNA) in both cases yielded solid clusters of cells/insulae, microfollicles, and isolated atypical cells. Considering the patient's past history, an initial diagnosis of metastasis from prostate adenocarcinoma was considered. However, immunohistochemical staining of liquid-based cytology specimens (Thin-Prep) showed diffuse positive results for TTF-1 and thyroglobulin. The patient underwent total thyroidectomy with bilateral neck dissection. Histologic and immunohistochemical evaluation showed a poorly differentiated oncocytic thyroid carcinoma with lymphovascular invasion and lymph node metastases. To our knowledge, this is the first description of the immunocytochemical evaluation of this rare variant of poorly differentiated thyroid carcinoma using FNA and liquid based cytology.

Solitary Brain Metastases from Thyroid Carcinoma: Study of 6 Cases

Aims and background

Although systemic metastases from thyroid cancer are relatively frequent, they rarely affect the nervous system and only exceptionally originate from well-differentiated carcinoma.

Methods

The authors describe 6 cases of solitary brain metastases from thyroid carcinoma, well-differentiated in 3 cases and anaplastic in the other 3 cases.

Results

Four patients were females and 2 males (M:F ratio, 1:2); average age was 51 yrs (range 48-56). On average, the interval between diagnosis of the thyroid tumor and appearance of the metastasis was 2.8 years (range 1-12 years) and was shorter in the anaplastic forms (1.2 versus 4.4 years). Average survival was 15 months (range 6-48 months); in particular, average survival was longer in patients with well-differentiated carcinoma (9 vs 21 months) as also in those who did not present other metastatic sites (6 vs 24 months). Death was due to systemic progression of the disease in 4 cases and to brain-relapse in the other 2 cases.

Conclusions

Surgery, radioactive iodine (where uptake is demonstrable), and radiotherapy are the main therapies available for metastases from thyroid carcinoma. However, survival of patients appears to be modified by the type of treatment performed.

Brain Metastases in Well-Differentiated Carcinoma of the Thyroid

Fifteen patients (4 males and 11 females) developed brain metastases from well-differentiated thyroid cancer within 1 month to 14 years of the initial diagnosis. One patient presented with a brain tumor. Except for 3 patients with unique brain metastases, all the others had extensive metastases in nodes, lungs and bones in various combinations. Brain metastases generally appeared after the onset of metastases at other sites. The histology of the brain tumor matched the primary pathology in the 6 operated cases. The treatment was surgery and external radiation in 6 cases, and radioiodine or chemotherapy in the others. Survival in general was less than 6 months after the diagnosis of brain metastases. The prognosis is poor once the onset of brain metastases is evident.

Simultaneous Occurrence of Medullary Carcinoma and Papillary Microcarcinoma of Thyroid in a Patient with Men 2A Syndrome. Report of a Case

We report a case of simultaneous multifocal medullary carcinoma and papillary microcarcinoma in a patient with several distinctive features of MEN 2A. The patient underwent total thyroidectomy and central lymph node dissection. The extreme rarity and pathological features of this occurrence are discussed. There is no known common cause of these 2 different tumor types; it may be a stochastic exception. However, several other possibilities such as a common precursor cell or a common tumorigenic stimulus offer interesting perspectives for speculation.

Synchronous multifocal medullary and papillary thyroid microcarcinoma detected by elastography

INTRODUCTION

A few cases of concomitant medullary and papillary carcinoma in the same thyroid nodule have been described in the literature. However, the presence of multiple foci of both types of malignancy in the same gland is very rare.

PRESENTATION OF CASE

A 39 year-old female with multiple thyroid nodules, elevated serum calcitonin levels and elastographic findings suggestive of thyroid malignancy, underwent total thyroidectomy and central neck dissection. Histology revealed the presence of one focus of medullary and one focus of papillary carcinoma on each thyroid lobe. Subsequently, the patient underwent treatment with radioactive iodine.

DISCUSSION

This is the third case of synchronous multifocal medullary and papillary thyroid carcinoma reported in the literature. Several theories for the simultaneous development of these malignant entities have been proposed.

CONCLUSION

Ultrasound elastography can be a useful, noninvasive tool in the assessment of thyroid nodules.

Simultaneous medullary and differentiated thyroid cancer: a population-level analysis of an increasingly common entity

BACKGROUND

Simultaneous medullary thyroid carcinoma (MTC) and differentiated thyroid carcinoma (DTC) is a rare entity. This is the first population-level analysis of the characteristics and outcomes of simultaneous MTC/DTC.

METHODS

In the Surveillance, Epidemiology, and End Results (SEER) database (1988-2008), patients with simultaneous MTC/DTC were retrospectively compared with those with MTC alone using χ(2), ANOVA, log-rank tests, Cox multivariate regression, and Kaplan-Meier analyses.

RESULTS

A total of 162 patients had simultaneous MTC/DTC; 1,699 had MTC alone. MTC was diagnosed first in 67.9 % of simultaneous MTC/DTC cases. Simultaneous MTC/DTC increased from 2.7 % of all MTCs in 1988-1997 to 12.3 % in 2003-2008. Compared with MTC alone, simultaneous MTC/DTC had smaller mean MTC tumor size (2.9 vs. 2.2 cm; p = 0.005) and lower rates of MTC extrathyroidal extension (25.4 vs. 16.8 %; p = 0.015) and distant metastases (15.7 vs. 9.3 %; p = 0.032). Patients diagnosed with DTC first had smaller mean MTC tumor sizes (p = 0.01), whereas patients diagnosed with MTC first had tumor sizes similar to those of MTC alone. Compared with MTC alone, patients with simultaneous MTC/DTC were more likely to receive thyroidectomy (84.7 vs. 93.2 %; p = 0.003) and radioisotopes (4.4 vs. 25 %; p < 0.001). On Kaplan-Meier analysis, disease-specific survival rates were higher for simultaneous MTC/DTC than for MTC alone (10-year survival rates 87 vs. 81 %; p = 0.056).

CONCLUSIONS

Simultaneous MTC/DTC is diagnosed earlier in tumor development than MTC alone, with a trend toward better prognosis. This entity likely represents a primary tumor with an incidental pathologic finding of a second malignancy. Each malignancy should be treated according to its respective stage and current guidelines.

Merged histological types of malignant thyroid tumor: experience and controversy

Malignant tumors of the thyroid that consist of merged histological types are a rare clinical entity, with an obscure pathogenesis and no consensus of opinion on nomenclature. Eight patients with merged histological types of thyroid malignant tumor at a single medical center were enrolled between January 1977 and December 2009. These patients were surgically treated and were followed postoperatively from 1 month to 34 years. Preoperative patient characteristics, B-type ultrasonography, computed tomography scan, thyroid function tests, postoperative pathology, immunohistochemistry, and prognosis data were collected. Merged histological types of thyroid malignant tumor accounted for 0.12% of all thyroid malignant tumors treated during this period. Preoperative imageology and laboratory data have no specific value toward diagnosis of merged histological types of thyroid malignant tumor. Merged histological types of thyroid carcinoma that had undergone radical resection in combination with hormonal therapy and I(131) radiotherapy achieved a satisfactory outcome, while other merged thyroid malignant tumors were usually associated with a poor prognosis. Prognosis depended on the highest grade among an individual group of malignant tumors.

Poorly differentiated carcinoma of the thyroid: validation of the Turin proposal and analysis of IMP3 expression

The Turin Proposal algorithm defines poorly differentiated carcinoma on the basis of the presence of solid/trabecular/insular growth pattern, absence of conventional nuclear features of papillary carcinoma, and the presence of at least one of the following features: convoluted nuclei, mitotic activity > or =3/10 HPF, or tumor necrosis. IMP3 appears to have diagnostic and prognostic value in many solid tumors, including thyroid carcinomas. We examined a series of follicular-cell carcinomas with prominent solid patterns diagnosed at Mayo Clinic (56 cases) (Rochester, MN, USA) and at the University of Turin (96 cases) (Northern Italy) to validate the Turin consensus criteria defining poorly differentiated carcinoma of the thyroid and to evaluate the prevalence and prognostic behavior of this tumor. On this series, we analyzed the expression of conventional markers by immunohistochemistry and we investigated the expression of IMP3 by both immunohistochemistry and qRT-PCR. The prevalence of poorly differentiated carcinoma among the USA cases was 1.8% (56/3128) and that in the cases of Northern Italy was 6.7% (96/1442). Tumor characteristics were similar in the cases from the USA and from Italy except for extensive vascular invasion and a prevalent insular growth pattern (lower the former, higher the latter in the Italian series). In univariate analysis, the risk of death was higher for age > or =45, tumors > or =4 cm, and IMP3 positivity. Multivariate analysis showed that the risk of death from poorly differentiated carcinoma was higher for age > or =45. The Turin consensus criteria can reliably select poorly differentiated carcinomas. Tumors from the USA and from Italy showed similar overall survival, although the prevalence of poorly differentiated carcinoma was higher in Northern Italy. Expression of IMP3 appears to be an adverse prognostic factor for poorly differentiated thyroid carcinoma.

Poorly differentiated thyroid carcinoma: 5 years after the 2004 WHO classification of endocrine tumours

Poorly differentiated thyroid carcinoma (PDTC) was originally described in 1983 but included in the WHO classification of thyroid tumours in the 2004 edition, only. The diagnostic problems encountered in the 5 years of application of the WHO criteria are reviewed here. A long debate is still going on about the nature of PDTC, its morphological diagnostic features, its clinical significance and its optimal therapeutic approach. A consensus conference held in Turin in 2006 confirmed the geographical differences among claimed classical forms of PDTC and suggested a diagnostic algorithm based on the presence of a solid/trabecular/insular growth pattern and of high-grade features, in line with the WHO definition of PDTC, capable to select tumours with a distinct aggressive clinical behaviour. This worked well for PDTC cases from mountain areas (e.g. Northern Italy), where most, if not all, thyroid carcinomas having high-grade features also share a solid/trabecular/insular pattern of growth. However, this scheme might be less easily applicable for American and Japanese cases, possibly due to heterogeneous architectural and cytological features; indeed some Authors still prefer to base their diagnostic work up on the recognition of high-grade features only, including mitotic index and necrosis, irrespective of the growth pattern.

Concurrent occurrence of medullary thyroid carcinoma and papillary thyroid carcinoma in the same thyroid should be considered as coincidental

OBJECTIVES

The simultaneous occurrence of medullary thyroid carcinoma (MTC) and papillary thyroid carcinoma (PTC) in the same thyroid gland is documented. In this study, we evaluated the prevalence and characteristics of patients with concurrent MTC and PTC. Design Retrospective analysis of patients with MTC in a single centre and review of the literature.

PATIENTS AND MEASUREMENTS

Patients with MTC who underwent initial surgical treatment between 1996 and 2006 at Asan Medical Centre, Seoul, Korea were enrolled. We additionally reviewed the medical records of patients who initially underwent surgery for Graves' disease (GD) or follicular thyroid carcinoma (FTC) during the same period. The concurrent occurrence rate of PTC in MTC patients was compared with that in GD and FTC patients.

RESULTS

Ten of 53 (19%) MTC patients displayed the concomitant PTC. In all 10 cases, the MTC and PTC components were separated by normal thyroid tissue, with the maximal diameters of PTC being less than 1.0 cm in the majority of patients. The rates of concurrent PTC in patients with MTC, GD and FTC were 19%, 15% and 19%, respectively, which were not significantly different.

CONCLUSIONS

Our results suggest that the occurrence of concurrent MTC/PTC is generally a simple reflection of incidental papillary microcarcinoma.

Poorly differentiated thyroid carcinoma: diagnostic features and controversial issues

Poorly differentiated thyroid carcinomas are a heterogeneous group of tumors occupying an area intermediate between well-differentiated follicular or papillary carcinoma and anaplastic carcinomas, from both a histopathogenetic and a clinical point of view. Large tumor series selected on the basis of structural and/or other morphological criteria showed that poorly differentiated carcinomas have a distinct biological behavior, and the classification of these tumors into a separate group appears justified, although strict homogeneous diagnostic criteria should be achieved and widely accepted to better characterize such tumor entity. Moreover, the identification of the prognostic parameters segregating aggressive from indolent cases has important clinical implications. Molecular data in the literature, although limited by the heterogeneous case series analyzed, identify ras alterations as the most common molecular alteration in poorly differentiated carcinomas, thus, depicting a peculiar molecular pathway in this tumor type as compared to well-differentiated follicular and papillary carcinomas. The present paper aims to review the various aspects of this tumor type, from morphology to immunohistochemistry and molecular abnormalities from a practical and daily practice-oriented point of view.

Poorly Differentiated Thyroid Carcinoma: The Turin Proposal for the Use of Uniform Diagnostic Criteria and an Algorithmic Diagnostic Approach

Poorly differentiated (PD) thyroid carcinomas lie both morphologically and behaviorally between well-differentiated and undifferentiated (anaplastic) carcinomas. Following the original description of this entity, different diagnostic criteria have been employed, resulting in wide discrepancies and confusion among pathologists and clinicians worldwide. To compare lesions occurring in different geographic areas and the diagnostic criteria applied in those countries, we designed a study with a panel of internationally recognized thyroid pathologists to develop consensus diagnostic criteria for PD carcinomas. Eighty-three cases were collected from Europe, Japan, and the United States, and circulated among 12 thyroid pathologists. Diagnoses were made without any knowledge of the clinical parameters, which were subsequently used for survival analysis. A consensus meeting was then held in Turin, Italy, where an agreement was reached concerning the diagnostic criteria for PD carcinoma. These include (1) presence of a solid/trabecular/insular pattern of growth, (2) absence of the conventional nuclear features of papillary carcinoma, and (3) presence of at least one of the following features: convoluted nuclei; mitotic activity >or=3 x 10 HPF; and tumor necrosis. An algorithmic approach was devised for practical use in the diagnosis of this tumor.

An evidence-based review of poorly differentiated thyroid cancer

BACKGROUND

Poorly differentiated thyroid cancer (PDTC) presents the endocrinologist and surgeon with challenges of recognition and treatment given the lack of consensus on histopathologic definition and limited literature on surgical and nonsurgical treatment.

METHODS

We offer an operational pathologic definition for PDTC, which should help guide future work in this area. Poorly differentiated thyroid cancer should include insular and trabecular variants but should not include solid type lesions (included by other workers) or more differentiated tumors that may have poor prognosis such as tall cell, columnar, diffuse sclerosing, and oncocytic lesions. Systematic evidence-based literature reviews focusing on two questions were carried out: (1) is PDTC associated with an intermediate prognosis relative to anaplastic and WDTC? and (2) What are the postoperative treatment options for poorly differentiated thyroid cancer?

CONCLUSIONS

We have found level IV evidence that PDTC is intermediate between WDTC and anaplastic cancers in terms of prognosis. It represents a disease where appropriate administration of aggressive treatment not typically necessary for routine WDTC and not effective for anaplastic disease may uniquely result in substantial benefit. Limited level IV data show conflicting results regarding 131I treatment benefit. Given lack of morbidity and potential for benefit, we recommend that 131I therapy be considered in all patients postoperatively. Recommendation regarding external beam radiotherapy (XRT) is based primarily on extrapolation from studies in forms of poor-prognosis WDTC where substantial data exist regarding treatment benefit. We recommend that external beam treatment be considered in all patients with PDTC with T3 tumors without distant metastasis, all patients with T4 tumors, and all patients with regional lymph node involvement.

Immunohistochemical analysis of thyroid-specific transcription factors in thyroid tumors

Thyroid transcription factor 1 (TTF1), thyroid transcription factor 2 (TTF2) and paired box gene 8 (Pax8) are demonstrated to play a crucial role for the differentiation and organogenesis of thyroid follicular cells. Their roles in thyroid carcinogenesis are not very clear. Because dedifferentiation is a common process in thyroid carcinogenesis, thyroid-specific transcription factors seem also to be involving in thyroid carcinogenesis. The purpose of the present paper was to investigate their expression in a broad spectrum of follicular cell tumors in different degrees of differentiation, from well-differentiated benign follicular adenoma to anaplastic carcinoma. Medullary (C cell) carcinoma was also included in the investigation. Results of immunohistochemical staining showed that nuclear localization of these transcription factors was gradually decreased corresponding to the progressive dedifferentiation of thyroid tumors. Also, abnormal cytoplasmic accumulation of TTF2 and Pax8 was detected in many tumors samples, which may indicate a subtle regulation mechanism on the function of these transcription factors. In conclusion, abnormal expression of TTF1, TTF2 and Pax8 was closely related to thyroid tumorigenesis.

How to define follicular thyroid carcinoma?

The appropriate diagnosis of follicular thyroid carcinoma (FTC) still depends on its histological discrimination from follicular adenoma (including the distinction of benign from malignant oncocytic variants), papillary thyroid carcinoma (particularly from the follicular variants) and poorly differentiated thyroid carcinoma. The use of immunohistochemical markers contributed only marginally to better defining FTC. The introduction of the micro array technique, however, may offer the possibility of getting a better insight into the natural history, as well as predicting the clinical course, of a given thyroid nodule. This review attempts to recapitulate common standards in the diagnosis of FTC, to summarise current molecular data available to distinguish FTC from other benign and malignant tumours and, finally, to outline future perspectives to define FTC on its specific genetic features.

Unusual widespread metastatic presentation of mixed medullary-follicular thyroid carcinoma

Mixed medullary-follicular thyroid carcinoma (MMFTC) is a rare tumor with a metastatic behavior that has not been fully appreciated. Scintigraphy and radioiodine entrapment propensity of its metastases remains largely undescribed. The authors present a case of MMFTC with widespread bone and soft-tissue metastases, where every known site of metastases concentrated radioiodine intensely. The patient responded well to radioiodine therapy. The report suggests that the tumor may have a propensity to metastasize to the skeleton, and the metastases retain the ability to accumulate radioiodine.

Poorly differentiated carcinomas of the thyroid with trabecular, insular, and solid patterns: a clinicopathologic study of 183 patients

BACKGROUND

The term poorly differentiated (PD) carcinoma was proposed 20 years ago to define aggressive, follicular-derived thyroid carcinomas with behavior intermediate between follicular/papillary and anaplastic carcinomas. Among the variable histologic patterns recognized in such tumors, trabecular-insular-solid (TIS) areas usually are predominant. Conversely, some authors pointed out that PD carcinomas are characterized by unequivocal, high-grade histology with atypias, high mitotic counts, and necrosis rather than by a specific growth pattern.

METHODS

The clinicopathologic features of a series of 183 thyroid carcinomas with predominant (n = 165 tumors) or focal (n = 18 tumors) TIS growth patterns were studied by univariate and multivariate overall survival analyses and were compared with clinical outcomes. Subgroups included tumors with predominant oxyphilic features (n = 66 tumors) and (residual) papillary carcinoma features (n = 24 tumors). Control groups of papillary (n = 68 tumors), follicular (n = 71 tumors), and anaplastic (n = 35 tumors) carcinomas also were included for overall survival analysis.

RESULTS

TIS carcinomas had an intermediate behavior between papillary/follicular and anaplastic carcinomas (P < 0.0001). Univariate and multivariate statistical analyses demonstrated that age > 45 years (P = 0.007), the presence of necrosis (P < 0.0001), and a mitotic count > 3 per 10 high-power fields (P = 0.01) were associated with poor outcome. A simplified scoring system based on statistically significant parameters allowed the identification of three prognostic subgroups (P < 0.0001).

CONCLUSIONS

PD TIS carcinomas overall followed a more aggressive course compared with differentiated thyroid carcinomas, irrespective of the extent of the TIS component. However, a numeric scoring system applied to specific clinicopathologic parameters further may identify three prognostic categories of patients who have significantly different survival rates at 5 years and 10 years.

Management of brain metastases from thyroid carcinoma: a study of 16 pathologically confirmed cases over 25 years

BACKGROUND

Brain metastasis is an uncommon, morbid complication of metastatic thyroid carcinoma. Because of its rarity, management often is problematic. To help contribute to the management of this disease entity, the authors present herein what to their knowledge is the largest series reported to date in which all patients had biopsy proven confirmation of their brain metastases.

METHODS

The authors report a series of 16 patients with metastatic thyroid carcinoma to the brain who were treated between 1976-2000. The Mayo Clinic database was used to locate and review charts and radiology and pathology reports, and all biopsy specimens were reviewed by one pathologist. The histologic types of carcinoma included 10 papillary carcinomas, 2 follicular carcinomas, 1 Hürthle cell carcinoma, 1 medullary carcinoma, 1 insular carcinoma, and 1 anaplastic carcinoma. Given the small sample size, statistical analyses were not performed.

RESULTS

Surgical resection of brain metastases was associated with a trend toward longer survival (20.8 months vs. 2.7 months for no surgical intervention in selected patients) Whole brain external beam radiation therapy produced disease regression in three of the four evaluable patients. Gamma knife radiosurgery and radioactive iodine therapy appear to play limited, but beneficial, therapeutic roles. Overall, survival after the diagnosis of brain metastasis is reported to be longer than that noted with other solid tumors (17.4 months), and the majority of patients die of their extracranial disease (85% in the current series).

CONCLUSIONS

The results of the current study indicate that local therapies appear to control brain metastases in the large majority of thyroid carcinoma patients with metastases to the brain.

Poorly differentiated carcinomas of the thyroid gland: a review of the clinicopathologic features of a series of 28 cases of a heterogeneous, clinically aggressive group of thyroid tumors

We evaluated the clinicopathologic, immunohistochemical, lectin histochemical, ultrastructural and morphometric characteristics of a series of 28 poorly differentiated carcinomas of the thyroid (PDCT). The 28 tumors were classified according to their predominant growth pattern as insular (n=12), trabecular (n=10) and solid subtypes (n=6). The overall mortality rate was 46%. No significant differences were found among the 3 subtypes. Data obtained by lectin histochemistry, electron microscopy, and morphometry point to a closer relationship of PDCT to follicular than to papillary carcinoma. Our results do not support the subdivision of PDCT into subtypes.

Single brain metastasis from thyroid cancer: report of twelve cases and review of the literature

Brain metastases from thyroid carcinoma is unusual, with a frequency of 1%. We report twelve patients, with single brain metastases and with a karnofsky performance scale score >60 at admission. No metastasis was seen during the uptake of iodine-131, even in the cases from differentiated thyroid carcinoma, suggesting absence of differentiation between primary and metastasic disease. The histopathology of thyroid carcinomas was anaplastic in five cases, differentiated in six, and medullary in one. Only in four patients, brain was the unique site of metastatic spread; in others, bones and lungs were also involved. All metastases were surgically removed, and all patients were treated with radiotherapy (45 Gy) in the postoperative course. The survival average was 19.8 months, and the quality of life was satisfactory in all patients. One patient remained alive till 5 years. Anaplastic histopathology and size of the primitive, and also bone involvement of thyroid disease were significant risk factors in our cases (p < 0.05). According to the literature, surgery is the best therapeutical choice. Alternative strategies in the management of brain metastasis, such as iodine-131 therapy, are discussed, paying particular attention to the relevant side effects.

Immunohistochemistry of ultimobranchial thyroid carcinomas in seven slaughtered cows and one bull

Eight thyroid gland epithelial tumors were found in 7 cows and 1 bull in a retrospective study of thyroid gland lesions in slaughtered cattle. All tumors were classified as ultimobranchial thyroid carcinomas based on morphology and immunohistochemistry. All tumors consisted of solid sheets and nests of polygonal to oval epithelial cells, with more sparsely dispersed colloid-filled follicles. Connective tissue separating nests of epithelial cells varied from delicate fibrovascular stroma to dense collagenous stroma. Fusiform epithelial cells with rare neural fibers and ganglion cells were present in 1 tumor. Cells within solid areas of these tumors were immunoreactive for calcitonin, calcitonin gene-related peptide, neuron-specific enolase, and synaptophysin. Colloid and follicle cells were immunoreactive for thyroglobulin. Few follicle cells also were reactive for calcitonin gene-related peptide. Neoplastic cells invaded the fibrous capsules in all 8 cattle. These tumors represented proliferation of a mixed population of undifferentiated cells, C cells, and thyroid follicular epithelial cells, presumably derived from the thyroid ultimobranchial bodies. These ultimobranchial carcinomas in slaughtered cattle are comparable to ultimobranchial tumors described in dairy bulls and the intermediate type of thyroid gland carcinomas (mixed thyroid medullary carcinomas) described in human beings.

Neuroendocrine marker expression in thyroid epithelial tumors

Tissue sections from 50 cases with thyroid tumors, composed of 11 follicular adenomas, 10 follicular carcinomas, 14 papillary carcinomas, 10 anaplastic carcinomas, and 5 medullary carcinomas, were immunohistochemically analyzed for representative neuroendocrine markers. Immunoexpression ratios of these neuroendocrine markers were as follows: Follicular adenomas, neuron-specific enolase (NSE)63.6%, synaptophysin (SynP) 45.5%, Leu7 27.3%, NCAM 45.5%, chromogranin A (CgA) 0%, SNAP25 0%; follicular carcinomas, NSE 90.0%, SynP 80.0%, Leu7 80.0%, NCAM 0%, CgA 0%, SNAP25 0%; papillary carcinomas, NSE 85.7%, SynP 78.6%, Leu7 100%, NCAM 7.0%, CgA 0%, SNAP25.0%; anaplastic carcinomas, NSE 10.0%, SynP 0%, Leu7 0%, NCAM 0%, CgA 0%, SNAP25 0%; medullary carcinomas, NSE 100%, SynP100%, Leu7 80.0%, NCAM 40.0%, CgA 100%, SNAP25 100%. The two follicular carcinomas, which were morphologically characterized by "insular" (or "alveolar") arrangements, showed distinct immunoexpression of NSE and SynP at the same time. By in situ hybridization (ISH), expression of mRNA for NSE was confirmed in cases with marked immunoexpression of NSE. Although no endocrine granules were found, our results suggested that a specific type of follicular carcinoma, i.e., insular variant, may be immaturely neuroendocrine-differentiated.

Mixed medullary-follicular thyroid carcinoma. Molecular evidence for a dual origin of tumor components

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.

Tumor-to-tumor metastasis to follicular variant of papillary carcinoma of thyroid

OBJECTIVE

To describe and document tumor-to-tumor metastases in the thyroid gland.

METHODS AND RESULTS

In this series we describe 3 cases of tumor-to-tumor metastasis in which the recipient tumor was a follicular variant of papillary thyroid carcinoma. The donor tumors and sites were small cell carcinoma of the lung, neuroendocrine carcinoma probably of pancreatic origin with initial presentation as liver metastasis, and clear cell carcinoma of the kidney with metastasis to liver and pancreas. The donor tumor cells infiltrated the substance of the follicular variant of papillary thyroid carcinoma, the nontumorous thyroid parenchyma, and the lymphovascular spaces. Small cell carcinoma and neuroendocrine carcinoma showed positive reactivity for neuroendocrine markers and were negative for thyroglobulin and calcitonin. The follicular variant of papillary thyroid carcinoma showed positivity with thyroglobulin and cytokeratin 19.

CONCLUSIONS

Although tumor-to-tumor metastases in thyroid gland are exceedingly rare, one should be aware of this phenomenon as the metastatic lesion may simulate a thyroid primary. History of a previous tumor and immunohistochemical stains can be helpful in distinguishing between primary and metastatic thyroid neoplasms.

Diagnosis of malignant epithelial thyroid lesions: fine needle aspiration and histopathologic correlation

Fine needle aspiration is a diagnostic tool useful as a guide to patient management. We believe that its role in solving the diagnostic dilemmas presented by thyroid nodules is still underappreciated. Current fiscal constraints in health care might bring about a wider use of this simple technique to select patients for surgery. Care in sampling a mass is essential to obtain aspirates that are representative of the lesion and adequate in quantity for interpretation. Several aspirates are needed from all but the smallest masses. Most thyroid carcinomas are well-differentiated with a low grade of malignancy. The majority of these are papillary carcinomas, which are easily diagnosed in good cytologic smears. With fine needle aspirates the goal is to diagnose a follicular neoplasm and to separate it from the adenomatoid nodule. The follicular neoplasm then can be classified as adenoma or carcinoma with the histologic sections. The minimally invasive carcinoma still can be challenging to recognize. We hope that the cytologic criteria and histopathologic correlations presented here will help general pathologists who interpret aspirates. We believe that in the near future additional immunohistochemical methods and genetic markers will be used increasingly to discriminate among the neoplasms and to provide prognostic information.

C-cell adenoma containing variously sized thyroid follicles in a horse

A thyroid gland tumor, showing unusual histology, was identified in a 13-year-old male Andalusian horse. Microscopically, the tumor consisted of neoplastic proliferation of C-cell (parafollicular cell) with cytoplasmic fine granules, containing diffusely distributed, variously sized colloid-containing follicles. Immunohistochemically, the neoplastic C-cell were positive for calcitonin and follicleforming epithelial cells showed a positive reaction for thyroglobulin. Ultrastructurally, membrane-bound secretory granules up to 250 nm in diameter were found in the cytoplasm of the parafollicular cells, whereas the follicular epithelial cells had microvilli, junctional complex, and well-developed endoplasmic reticulum.

Selection of the optimal scanning agent for thyroid cancer

Physical and biologic principles, availability, and experience in use determine which radiopharmaceuticals will be the optimal agents to portray scintigraphically thyroid cancers. However, clinical reasoning must dictate which scanning procedure to use and when. To identify functioning thyroid nodules, and thereby exclude malignancy and also disclose the source of excess thyroid hormone, technetium Tc 99m pertechnetate is the agent of choice. To evaluate patients with metastatic differentiated thyroid cancer (DTC) for possible radiopharmaceutical therapy, low doses (no more than and probably less than 74 MBq or 2 mCi) of 131I iodide are preferred. 131I is especially necessary if dosimetry is undertaken to help prescribe the optimal therapeutic dose of 131I. For less well differentiated tumors that do not concentrate 131I, most experience has been with thallium 201, which enables depiction of most metastases, but, in time, newer agents may be found to produce superior scans. The goal of imaging of the less well differentiated cancers must be to direct additional therapy such as external beam radiation of surgical excision. It is unlikely that any scanning procedure that depends on the physiologic and biochemical activities of DTC will have as much sensitivity for locating tumors in the euthyroid as in the hypothyroid patient. A majority of medullary carcinomas of the thyroid (MCT) have been portrayed by indium 111 octreotide and by 99mTc pentavalent dimercaptosuccinic acid; other agents have concentrated to lesser levels in the tumors or have not been investigated as extensively. As of now, metastatic MCT defies therapy, and, therefore, scanning to detect the tumors has little clinical utility.

Concurrent medullary and papillary carcinomas of thyroid with lymph node metastases. A collision phenomenon

The simultaneous occurrence of two distinct neoplasms derived from different cells of origin is a recognized, albeit rare, entity. In the thyroid, such lesions could consist of medullary carcinoma composed of parafollicular C cells and well-differentiated carcinoma showing follicular epithelial cell differentiation. We report a patient whose thyroid contained calcitonin-immunoreactive medullary carcinoma and thyroglobulin-positive papillary carcinoma, clearly separated from each other. The tumors metastasized to regional lymph nodes, where they formed foci of composite medullary and papillary carcinoma, with each component maintaining a distinct immunophenotypic profile. The composite metastases are best regarded as collision tumors, as each primary neoplasm exhibited only one line of differentiation. Given the high incidence of papillary carcinoma, the occurrence of the two tumors may be a coincidence. Alternatively, a common tumorigenic stimulus triggering neoplastic transformation of both parafollicular C cells and follicular epithelial cells is a plausible explanation for such a phenomenon.

The Pathology of Medullary Carcinoma of the Thyroid: Review of the Literature and Personal Experience on 62 Cases

The aim of the present review is to analyze the numerous pathological patterns of medullary carcinoma of the thyroid (MCT) and discuss the problems of differential diagnosis with other thyroid and nonthyroid tumors. In addition, morphological parameters and phenotypic features were related to the clinical outcome. The recent literature was reviewed and compared with the features of 62 MCTs observed at our institution. The most common patterns of growth are trabecular, alveolar and spindle cells, but MCT can mimic virtually all other primary thyroid tumors and some nonthyroid neoplasms. This heterogeneity has no proven implications for prognosis, but is of relevance for diagnostic purposes, as the differential diagnosis of MCT can be difficult in nonclassical cases. In agreement also with the literature data, no relationship between histopathological parameters and outcome was found in our series, although clinically aggressive tumors had a more advanced stage at presentation. Immunocytochemica demonstration of calcitonin is apparently the only valid criterion for a correct typing of MCT. Chromogranin A is an additional sensitive marker of MCT and parallels calcitonin expression in the majority of cases.

Thyroid medullary carcinoma with thyroglobulin immunoreactivity in sporadic multiple endocrine neoplasia type 2-B

BACKGROUND

Thyroid carcinomas historically have been divided into two groups according to their presumedly separate embryonic origins: those of neuroectodermal derivation (parafollicular or medullary carcinoma [MCT]) and those of foregut endodermal origin (follicular and papillary carcinomas). The validity of this concept has been questioned by the recognition that some MCT may show immunocytochemical and ultrastructural evidence of follicular components, and display features of follicular function (e.g., organification of iodine, immunoreactivity for thyroglobulin).

METHODS

A 14-year-old boy presented with the physical features of multiple endocrine neoplasia type 2-B (MEN 2B) and a thyroid mass. His thyroid lesion was studied by light microscopy; electron microscopy; immunohistochemistry using antisera to calcitonin, thyroglobulin, and other peptides; and in situ hybridization.

RESULTS

The tumor was identified as an MCT by light microscopy. It stained positively with calcitonin, thyroglobulin, chromogranin, neuron-specific enolase, and serotonin. At the ultrastructural level, the tumor cells contained numerous neurosecretory granules and showed evidence of follicular differentiation (luminal microvilli, follicle formation, and tight junctions), suggesting a dual neuroendocrine and follicular differentiation.

CONCLUSIONS

The morphologic findings suggest that a small number of MCTs arise from a common stem cell (possibly the ultimobranchial body) that may give rise to both MCT and follicular carcinoma. This patient and patients in similar cases documented in the literature challenge the classic concept of separate pathways of embryogenesis for these two cell types.

Medullary carcinoma of the thyroid with carcinoid-like features

AIMS

To show that medullary carcinomas of the thyroid are morphologically indistinguishable from gut carcinoids: the value of histochemistry in their identification and differential diagnosis from metastatic carcinoid tumours to the thyroid and some follicular cell neoplasms.

METHODS

15 thyroid medullary carcinomas with features of gut carcinoids were histochemically studied for the presence of argyrophil and argentaffin granules, and calcitonin, thyroglobulin, and serotonin immunoreaction.

RESULTS

Histological features of midgut (classic) carcinoids were observed in two tumours, foregut carcinoids in 12, and hindgut carcinoids in one. All tumours showed, to a greater or lesser extent, a calcitonin immunoreaction and argyrophilia. These markers were present only in a small area showing a classic pattern of thyroid medullary carcinoma in the hindgut carcinoid-like neoplasm. Argentaffin granules and serotonin immunostaining occurred in occasional cells from four foregut carcinoid-like tumours. Thyroglobulin was not expressed in all cases and amyloid stroma was expressed in three.

CONCLUSIONS

In some cases a diagnosis of metastatic carcinoid tumour to the thyroid can be considered only after ruling out clinically and histochemically medullary carcinoma of the thyroid. Immunolocalisation techniques are also essential for the differentiation between medullary carcinoma and thyroid follicular cell neoplasms that resemble carcinoid tumours. It is proposed that this tumour variant to be incorporated into current classifications as another histological subtype of C cell carcinoma.

Immunocytochemical study of the ultimobranchial tubule in Wistar rats

A systematic immunohistochemical study of the ultimobranchial tubule (UBT) has been carried out in 45 Wistar rats of different ages (0, 5, 10, 15, 20, 25, 30, 60 and 120 days). The existence of calcitonin immunoreactive cells in the UBT wall has been demonstrated in a 5-days old rat. In addition, immunohistochemical studies for thyroglobulin revealed positive staining in follicular cells connected to the UBT and, occasionally, in isolated cells lying within solid clusters from the UBT. These last results together with the continued and repeated existence of numerous mitosis and PAS (+) microfollicles, apparently rising from the UBT, support the hypothesis that the ultimobranchial body (UBB) may contribute partially to the formation of a part of the follicular component.

Chromogranin A immunoreactivity compared with argyrophilia, calcitonin immunoreactivity, and amyloid as tumour markers in the histopathological diagnosis of medullary (C-cell) thyroid carcinoma

Applying the WHO criteria for the histopathological diagnosis of medullary thyroid carcinoma (MTC)--as well as the criterion that a significant amount of argyrophil cells, amyloid deposits, or calcitonin (CT) immunoreactive cells shall be present--122 cases were identified from the files of the Swedish Cancer Registry. Both non-occult (n = 110) and "occult" (less than 1 cm in diameter) (n = 12) MTCs were included. Both primary tumours (n = 91) and metastatic lesions (n = 31) were investigated. The specimens available were all only conventionally formalin-fixed and paraffin-embedded. The presence of neoplastic cells immunoreactive with antisera against chromogranin A (Chr A) was compared with that of the other three MTC markers. Chr A immunoreactive cells were present in practically all the cases. Similar results were obtained when the argyrophil reaction alone and CT immunoreactivity alone were used as markers. When two of the three MTC markers were combined, it was found that virtually everyone of the 122 tumours could be identified as a MTC. In contrast, the presence of amyloid deposits was found to be a less constant MTC marker; whereas 94% of the primary tumours had amyloid deposits, they were present in only approximately 70% and 60% of the metastatic and "occult" tumours respectively. No differences in the staining reaction patterns were found between familial (n = 18) and the sporadic (n = 104) types of MTC.(ABSTRACT TRUNCATED AT 250 WORDS)

Immunocytochemistry of canine thyroid tumors

Immunocytochemical studies using the peroxidase-antiperoxidase method with commercial antibodies against thyroglobulin, calcitonin, calcitonin gene-related peptide (CGRP), neuron specific enolase (NSE), somatostatin, and neurotensin were performed on 38 Bouin-fixed, paraffin-embedded canine thyroid tumors obtained from necropsy and surgical files from 2 Ecoles Nationales Vétérinaires (Alfort and Nantes, France) and from the Laboratoire d'Histo-Cytopathologie Vétérinaire, Maisons-Alfort (France). The tumors consisted of two follicular adenomas, nine follicular carcinomas, nine solid carcinomas, 12 follicular-compact-cellular carcinomas, and six C-cell carcinomas. All 32 follicular-cell tumors were stained positively for thyroglobulin, half of them had weak to moderate positive immunoreactivity for NSE, and all histologic patterns were represented. They had no immunoreactivity for somatostatin or neurotensin. Four C-cell carcinomas had a solid alveolar pattern, while two had a pseudo follicular pattern characterized by uneven, often coalescent, pseudo-follicular formations with a multilayered epithelium surrounding a cavity that often contained red blood cells. Four C-cell carcinomas had uneven immunoreactivity for calcitonin, while all six were positive for CGRP or NSE. Immunoreactivity for CGRP was stronger or more widespread than positivity for calcitonin when both occurred in the same tumor. Some cells of three C-cell carcinomas had positive immunoreactivity for somatostatin. No immunoreactivity for neurotensin was detected. Seven tumors of follicular cell origin contained a few cells positive for calcitonin or CGRP, while three C-cell carcinomas had a few cells positive for thyroglobulin. These tumors were considered to contain entrapped remnants of normal thyroid tissue rather than being dual hormone producing tumors.

Thyroglobulin in human thyroid follicles with acid mucin

The minority of human thyroid follicles that contain acid mucin are often grouped in the C-cell area of the gland, and are lined by abundant C cells. They are thought to be derived from the ultimobranchial contribution to the thyroid gland. This study demonstrates the presence of thyroglobulin reactive follicular cells and colloid as well as calcitonin and CGRP in these ultimobranchial-related thyroid follicles. These findings add further support to the belief that the ultimobranchial body is a source of at least some C cells and follicular cells, and support the view that thyroid mixed medullary follicular neoplasia may originate from an ultimobranchial stem cell line.

Intermediate thyroid carcinoma in humans and ultimobranchial tumors in bulls: A comparative morphological and immunohistochemical study

The intermediate type of thyroid carcinoma in humans has been defined as having characteristics of both follicular and parafollicular cell carcinoma. The ultimobranchial (UB) body in mammals is believed to harbor stem cells capable of developing both follicular and parafollicular cells. Hyperplastic and neoplastic lesions of the UB remnants and of the parafollicular cell system frequently occur in bulls. Such lesions, found in 64 individuals (6%) derived from an autopsy material of 1,101 bulls, have been compared structurally and immunohistochemically with 18 human cases of thyroid carcinoma of the intermediate type, in order to define their possible biological relationship. UB changes in bulls formed a continuum ranging from hyperplastic nodules to gross tumors. They contained all epithelial components present in the normal UB remnants in cattle: UB cysts and tubules and solid nests of small basophilic immature cells, which were immunocytochemically indifferent, as wellas mature follicular and neuroendocrine cells. The indifferent cell component dominated in most bull tumors; a minority were mainly formed by mature follicular or parafollicular cells. Human tumors resembled the bull UB tumors structurally and immunohistochemically, although generally the degree of maturation was higher in human tumors. A few were mainly formed by indifferent immature cells and contained typical UB cysts and tubules. One bull tumor and one human tumor contained amyloid. UB changes in bulls were invariably associated with a marked hyperplasia of the parafollicular cell system, in some cases even with tumor development. A similar hyperplasia, but without neoplastic change, was found in 4 of 11 human cases in which nontumorous thyroid parenchyma was available for examination.The findings suggest that intermediate thyroid carcinoma rather than medullary carcinoma is the human equivalent to the bull UB tumors. It is concluded that although both the medullary and the intermediate type of carcinoma appear to be histogenetically related to the UB body, the former shows evidence of a pure parafollicular cell differentiation, whereas the latter develops both follicular and parafollicular, as well as intermediate, cell forms and sometimes also immature structures of the type seen in UB remnants of the adult human thyroid gland.

Mixed medullary-papillary carcinoma of the thyroid: a previously unrecognized variant of thyroid carcinoma

Two unusual medullary carcinomas of the thyroid gland and their metastases contained a population of cells (20% to 25%) with the characteristic clear nuclei of papillary carcinoma. The predominant component of the tumors exhibited the typical growth pattern and cytologic features of medullary carcinoma with abundant amyloid deposits. The cells with clear nuclei lined follicle-like or tubular structures. In both the primary and the metastatic lesions, immunoreactive thyroglobulin was demonstrated only in the cells with clear nuclei, while calcitonin, carcinoembryonic antigen, and neuron-specific enolase were present only in cells of the predominant medullary carcinomatous component. Moreover, intense and diffuse staining for cytokeratin was seen only in the cells with clear nuclei, but not in those of the major medullary carcinomatous component. These findings suggest the existence of a distinctive variant of mixed medullary-papillary carcinoma that can be recognized with routine stains.