Concurrent lymph node metastases of medullary and papillary thyroid carcinoma in a case with RET oncogene germline mutation

Mixed Medullary-Papillary Thyroid Carcinoma with Mixed Lymph Node Metastases: a Case Report and Review of the Literature

Papillary thyroid and medullary thyroid cancers are two distinct types of thyroid neoplasms. Co-occurrence of these cancers is rare, especially in mixed tumours with lymph node metastases. A 66-year-old man presented with a thyroid tumour. Thyroid ultrasonography revealed three separate nodules in the thyroid, suspected to be associated with lymph node metastasis. Although preoperative thyroid function was normal, calcitonin and carcinoembryonic antigen levels were elevated. The patient underwent a total cervical thyroidectomy with bilateral radical dissection. Histological and immunohistochemical analyses identified mixed medullary and papillary thyroid carcinoma (MMPTC) in the nodules in the left lobe of the thyroid and the isthmus. Mixed metastatic spread was observed in several lymph nodes from the neck dissection specimen. Accurate diagnosis of the rare co-occurrences of papillary and medullary thyroid carcinomas is crucial. TSH suppression can be effective for treating papillary thyroid carcinoma, whereas radical surgery is the preferred treatment for medullary thyroid carcinoma. Identifying lymph node metastasis before surgery is a key surgical strategy.

Thyroid Collision Tumors: The Presence of the Medullary Thyroid Carcinoma Component Negatively Influences the Prognosis

Thyroid collision tumors (TCTs) are rare pathological findings, representing <1% of thyroid cancers. This study aimed to compare the main pathological features of TCTs containing medullary thyroid carcinoma (MTC) and papillary thyroid carcinoma (PTC) components with MTC-only tumors and PTC-only tumors. Methods: The retrospective study included 69 cases diagnosed with TCTs (with simultaneous MTC and PTC components), MTC and PTC. All tumors were comparatively assessed for the classical histopathological prognostic features, including a new grading system for MTC. Results: The main component of TCTs had more frequent microscopic extrathyroidal extension (mETE) (p = 0.000), lymphovascular invasion (LVI) (p = 0.000), perineural invasion (PNI) (p = 0.044), and lymph node metastasis (p = 0.042). Additionally, the TCTs’ MTC component presented with more frequent LVI (p = 0.010). Comparing TCTs’ MTC and PTC components with MTC-only tumors and PTC-only tumors revealed that only the TCTs’ MTC components had statistically significant more frequent mETE (p = 0.010) than MTC-only tumors. When applied to the MTC component of TCTs, the pathological parameters of the new grading system of MTC showed no correlations with other microscopic or clinical aspects. Conclusion: Using classical pathological prognostic features, the comparative analysis revealed that the main TCTs’ component was more aggressive than the minor one. Contrary to PTCs, in TCTs, the medullary component was more aggressive than the papillary one, but also more aggressive than MTC-only tumors.

The Growth Kinetics of Collision Nodal Metastasis from Medullary and Papillary Thyroid Carcinomas: A Case Report

INTRODUCTION

The collision of medullary (MTC) and papillary thyroid carcinoma (PTC) in the same cervical lymph node can occur, but its growth kinetics has not been reported.

CASE PRESENTATION

We report a 27-year-old male patient who had collision nodal metastases from PTC and sporadic MTC in the central compartment. This was treated with total thyroidectomy and central neck dissection. The collision nodal metastasis persisted and presented with a single sonographically enlarging central compartmental lymph node postoperatively. The volume of the collision nodal metastasis increased from 226 to 507 mm³ over the first 8 months, from 507 to 572 mm³ over the next 6 months, and from 572 to 762 mm³ over the next 31 months. The calcitonin and carcinoembryonic antigen (CEA) fluctuated in the first 19 months followed by a steady increase at a doubling time of 1.97 and 8.42 years, respectively. Unstimulated thyroglobulin remained at 0.2 ng/mL or lower during the same period while thyrotropin (TSH) was not suppressed. Revision central neck dissection performed 4.5 years later resulted in undetectable serum calcitonin, CEA of 2 ng/mL, and thyroglobulin of 0.1 ng/mL from a preoperative calcitonin of 212 ng/L, CEA of 10 ng/mL, and thyroglobulin of 0.2 ng/mL. Further structural imaging 13.5 months later revealed no evidence of disease.

DISCUSSION

The growth kinetics of collision nodal metastasis from PTC and MTC can be similar to conventional PTC and MTC. Furthermore, the growth rate of such collision nodal metastases can be slow. Guided by tumor marker doubling time and regular structural imaging, surgical salvage performed after a period of active surveillance may still result in biochemical and structural remission.

Mixed medullary-papillary thyroid carcinoma with mixed lymph node metastases: A case report

Mixed medullary-follicular-derived carcinoma is a very rare event. It is extremely important to make the correct diagnosis, due to prognostic and treatment implications. A genetic study of these patients is advisable to exclude the presence of MEN 2.

Papillary and Medullary Thyroid Carcinomas Presenting as Collision Tumors: A Case Series of 21 Cases at a Tertiary Care Cancer Center

Collision tumor is the occurrence of two histologically and morphologically distinct tumors within the same organ with no histological admixture. Collision tumors of the thyroid are extremely rare constituting < 1% of all thyroid tumors. Clinical profiles and pathological features of Medullary thyroid carcinoma (MTC) and Papillary thyroid carcinoma (PTC) presenting as Collision tumors of thyroid, diagnosed between 2009 and 2019, at a tertiary care cancer center were retrospectively analyzed. Collision tumors comprised 4.7% of all MTC cases diagnosed over 10 years. A total of 21 cases (11males, 11 females, M:F = 1) were retrieved with the mean age of patients being 45.33 years (range 26-77 years). More than half of PTCs involved the right lobe of the thyroid (66.6%). About half (53.4%) of MTCs affected the left lobe. Imaging done pre-operatively failed to identify the smaller second tumor in 60% of the cases with both tumours in separate lobes. Pre-operative FNAC showed only MTC in all 8 cases in which it was done. Papillary microcarcinoma (m-PTC) was seen in 85.7% cases, with one case of multifocal m-PTC. MTC (mean size 3.12 cm), on an average, was 3 times larger than the PTC (mean size 0.91 cm). The histological variants of MTC included-oncocytic (1/21, 4.7%), spindle cell (1/21, 4.7%), epithelial (3/21, 14.2%) and classical (16/21, 76.2%) and of PTC included classic PTC (12/21, 57.14%), Hurthle cell (2/21, 9.52%), tall cell (1/21, 4.76%) and follicular variant of PTC (6/21, 28.57%). The microscopic extrathyroidal extension (ETE) due to MTC and PTC component was 42.8% and 9.5% respectively. Lymph node metastasis was seen in 16 (76.2%) cases; 87.5% (14/16) of which were contributed by MTC, 12.5% (2/16) by PTC alone, and 12.5% (2/16) cases showed metastasis from both MTC and PTC. MTC had a higher stage than PTC in 85.5% of cases. Collision tumors of the thyroid are exceedingly rare, and possibly underdiagnosed due to variation in sampling techniques, especially of the grossly "normal lobe". The low incidence in our cohort is in favor of the "Chance theory" of co-occurrence. This diagnosis is important due to its therapeutic and prognostic implications.

Medullary Thyroid Carcinoma and Papillary Thyroid Carcinoma in the Same Patient as a Collision Tumour

Aim

Papillary thyroid carcinoma (PTC) and medullary thyroid carcinoma (MTC) are two different types of thyroid carcinoma with significant different clinical and histological findings. Their coexistence in the same patient is a very rare event which demands different clinical approach.

Case Report

We report a case with concurrent MTC and PTC in the same thyroid having characteristics of a collision tumour. A 35-year-old patient has admitted to endocrinology outpatient department with complaint of pain in the neck. Physical examination revealed 2 cm nodule on the thyroid right lobe. Serum thyroid hormone levels were within normal range. Ultrasonography revealed a 23x15 mm hypoechoic nodule with micro calcifications and cystic areas on the right lobe. Preoperative serum calcitonin was 2 pg/ml (0-11.5). PTK 1.7 cm and MTK 1.8 cm in the same thyroid with healthy tissue in between them were detected on pathological examination. RET gene mutation was negative. She has been followed up to now without any evidence of disease.

Conclusion

This is a collision tumour since lesions with features of MTC and PTC were detected in two different locations and separated by normal thyroid tissue. Germline point mutation of the RET gene had a potential role in the development of both MTC and PTC. On the other side, familial concurrent MTC and PTC without RET gene mutation was also published. Both RET and BRAF genes had a role in the development of the medullary and papillary collision tumours. We do not know the presence of BRAF gene mutation in this case report yet.

Classical point mutations of RET, BRAF and RAS oncogenes are not shared in papillary and medullary thyroid cancer occurring simultaneously in the same gland

BACKGROUND

Papillary (PTC) and medullary (MTC) thyroid carcinomas represent two distinct entities, but quite frequently, they may occur simultaneously.

AIM

To provide genetic analysis of PTC and MTC occurring in the same patient (PTC/MTC) to elucidate their origin.

METHODS

Sequencing analysis of RAS, BRAF and RET oncogenes hot spots mutations in tumoral and normal tissues of 24 PTC/MTC patients.

RESULTS

Two of 24 patients (8.3 %) were affected by familial MTC (FMTC) harboring RET germline mutations in all tissues. Eight of 22 (36.4 %) sporadic cases did not show any somatic mutation in the three tissue components. Considering the MTC component, 10/22 (45.4 %) patients did not show any somatic mutation, 7 of 22 (31.8 %) harbored the M918T RET somatic mutation and 4/22 (18.2 %) presented mutations in the H-RAS gene. In an additional case (1/22, 4.6 %), H-RAS and RET mutations were simultaneously present. Considering the PTC component, 1 of 24 (4.2 %) patients harbored the V600E BRAF mutation, 1 of 24 (4.2 %) the T58A H-RAS mutation and 1 of 24 (4.2 %) the M1T K-RAS mutation, while the remaining PTC cases did not show any somatic mutation. In one case, the MTC harbored a RET mutation and the PTC a BRAF mutation. None of the mutations found were present in both tumors.

CONCLUSIONS

To our knowledge, this is the first study analyzing a possible involvement of RET, BRAF and RAS oncogene mutations in PTC/MTC. These data clearly suggest that the classical activating mutations of the oncogenes commonly involved in the pathogenesis of PTC and MTC may not be responsible for their simultaneous occurrence.

Papillary thyroid carcinoma and multiple endocrine neoplasia type 2

INTRODUCTION

Papillary thyroid carcinoma (PTC) is exceptional in MEN 2.

RESULTS

The analysis in 135 patients revealed two PTC, without C-cell pathology; both being positive for V804M mutation (RET proto-oncogene).

CONCLUSIONS

Few data are available about PTC in MEN 2, and without C-cell pathology is even less common. More studies are needed to correlate genetics and histology, and even for assessing PTC as only manifestation of MEN 2.

Collision tumors of the thyroid: A case report and review of the literature

BACKGROUND

Collision tumors of the thyroid are a rare pathology that present a diagnostic and treatment challenge. In this report, we present an interesting case and a review of the current literature as to inform management.

METHODS AND RESULTS

An 88-year-old woman presented with acute airway compromise and vocal cord paralysis. CT identified a thyroid mass and widespread metastasis. Histopathology identified the lesion as a collision tumor consisting of a squamous cell carcinoma (SCC) and papillary thyroid carcinoma. The patient was managed with surgery and palliative radiotherapy. However, she died from complications of a lower respiratory tract infection. We also present a review of the literature with 33 cases reviewed.

CONCLUSION

Management of collision tumors is complex because of the duality of the pathology. They should be managed in a multidisciplinary team setting and treatment should be patient specific. Generally, the most aggressive neoplasm should guide treatment. We recommend surgical management with adjunct therapy.

Synchronous occurrence of medullary and papillary carcinoma of the thyroid in a patient with cutaneous melanoma: determination of BRAFV600E in peripheral blood and tissues. Report of a case and review of the literature

The purpose of this study is to describe a case of concurrent medullary and papillary thyroid carcinoma (MTC and PTC) and cutaneous melanoma and to analyze BRAF(V600E) mutation in plasma and tissues. We report the clinical history and the laboratory, imaging, and histopathological findings of a 47-year-old man affected by multinodular goiter. BRAF(V600E)-mutated DNA was quantified in plasma samples and in cancer sections by quantitative real-time polymerase chain reaction (qPCR). At ultrasound examination, the dominant right nodule of the thyroid was weakly hyperechoic and hypervascularized, while the left one was hypoechoic without internal vascularization. Regional lymphadenomegalia was not detected. Basal plasma calcitonin was elevated, and the patient underwent total thyroidectomy and resection of central cervical lymph nodes. Histopathological examination identified two distinct foci of MTC and PTC and micrometastasis of well-differentiated carcinoma in one of the six resected lymph nodes. RET proto-oncogene germline mutations were not detected. Cutaneous melanoma of the thorax was subsequently diagnosed. BRAF(V600E) tissue DNA was detected in PTC and melanoma but not in MTC. The cell-free plasma percentage of BRAF(V600E) DNA was detected in pre-thyroidectomy peripheral blood and was drastically reduced after cancer treatments. This study confirms the occurrence of synchronous MTC and PTC and is the first evidence of the co-existence of melanoma and distinct thyroid cancers of different origin. BRAF(V600E) allele was detected in PTC and melanoma but not in MTC tissues. BRAF(V600E) molecular quantification in pre- and post-treatment blood supports our previous data, suggesting its possible role in diagnosis and follow-up of BRAF-positive tumors.

Simultaneous occurrence of medullary and papillary thyroid microcarcinomas: a case series and review of the literature

Introduction

Papillary thyroid microcarcinoma has been demonstrated to present in association with medullary thyroid carcinoma, however, medullary thyroid carcinoma and papillary thyroid carcinoma represent rare entities. In recent years this rarity has been increasingly observed. The pathogenesis is still controversial. Genetic analysis of RET proto-oncogenes in cases of simultaneous papillary thyroid carcinoma and medullary thyroid carcinoma has so far provided conflicting results; although it seems that germline mutations play a potential role in the development of both histological types.

Case presentations

This paper describes four rare cases of simultaneous medullary thyroid carcinoma and papillary thyroid microcarcinoma with unique features:

Case one was a 43-year-old Jewish woman, born in Israel, daughter of a Latvian immigrant mother and a father born in Israel. Case two was a 44-year-old Arab woman born in Israel. Case three was a 45-year-old Jewish woman, born in Israel, daughter of Moroccan immigrant parents and is unique for the presence of lymph node metastatic medullary thyroid carcinoma, and one lymph node with metastatic papillary carcinoma found in the same side. Case four was a 77-year-old Jewish woman, born in Iraq. These cases are unique in their composition of thyroid carcinoma, consisting of histologic features of medullary thyroid carcinoma, papillary thyroid microcarcinoma, and follicular thyroid adenoma. The four cases represent different ethnicity groups that live in north Israel, and case four is notable for the advanced age of the patient (77 years).

Conclusion

These four cases add more data supporting the coincidental coexistence of papillary thyroid microcarcinoma and medullary thyroid carcinoma; our results may suggest that the simultaneous occurrence of medullary thyroid carcinoma and papillary thyroid microcarcinoma is generally a simple reflection of this coincidence. Endocrinologists and pathologists should be aware of this entity. The pathologist can play a pivotal role in identifying papillary thyroid microcarcinoma in concurrent existence with medullary thyroid carcinoma.

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.

Medullary and papillary carcinoma of the thyroid gland occurring as a collision tumor with lymph node metastasis: A case report

Introduction

Papillary thyroid carcinoma and medullary thyroid carcinoma are two different thyroid neoplasia. The simultaneous occurrence of medullary thyroid carcinoma and papillary thyroid carcinoma as a collison tumor with metastases from both lesions in the regional lymph nodes is a rare phenomenon.

Case presentation

A 32-year-old Iranian man presented with a fixed anterior neck mass. Ultrasonography revealed two separate thyroid nodules as well as a suspicious neck mass that appeared to be a metastatic lesion. The results of thyroid function tests were normal, but the preoperative calcitonin serum value was elevated. Our patient underwent a total thyroidectomy with neck exploration. Two separate and ill-defined solid lesions grossly in the right lobe were noticed. Histological and immunohistochemical studies of these lesions suggested the presence of medullary thyroid carcinoma and papillary thyroid carcinoma. The lymph nodes isolated from a neck dissection specimen showed metastases from both lesions.

Conclusions

The concomitant occurrence of papillary thyroid carcinoma and medullary thyroid carcinoma and the exact diagnosis of this uncommon event are important. The treatment strategy should be reconsidered in such cases, and genetic screening to exclude multiple endocrine neoplasia 2 syndromes should be performed. For papillary thyroid carcinoma, radioiodine therapy and thyroid-stimulating hormone suppressive therapy are performed. However, the treatment of medullary thyroid carcinoma is mostly radical surgery with no effective adjuvant therapy.

Synchronous metastatic medullary and papillary thyroid carcinomas in a patient with germline RET mutation: case report, molecular analysis, and implications for pathogenesis

The occurrence of medullary thyroid carcinoma (MTC) in patients with germline RET mutation is well established, but the occasional occurrence of papillary thyroid carcinoma (PTC) in this setting remains unexplained. We report a case of synchronous MTC and PTC in a patient with germline RET mutation, and investigate the molecular pathogenesis of these two tumors. A 48-year-old man presented with cervical lymphadenopathy and was found to have metastatic MTC involving cervical and mediastinal lymph nodes. He underwent thyroidectomy and debulking of metastatic disease. The resected thyroid showed bilateral MTC and a 1-cm PTC. His lymph node metastases were predominantly MTC along with a small focus of metastatic PTC. Molecular testing using peripheral blood revealed a germline RET point mutation (Val804Met). Both tumors were analyzed for the BRAF (Val600Glu) mutation and the RET/PTC1 translocation. The PTC was positive for the BRAF mutation but negative for RET/PTC1. The MTC was negative for both abnormalities. We conclude that the MTC was caused by the germline RET mutation, while the PTC was caused by a somatic BRAF mutation. The occurrence of PTC in patients with germline RET mutations appears to be purely coincidental.

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.

When is prophylactic thyroidectomy indicated for patients with the RET codon 609 mutation?

BACKGROUND

Mutations in the RET proto-oncogene cause multiple endocrine neoplasia type 2A (MEN2A), and prophylactic thyroidectomy has generally been recommended before the age of 5 years. Patients with codon 609 mutations develop MTC at a later age and therefore the timing of prophylactic thyroidectomy is less clear. We report a three-generation family with C609Y RET mutation where members having prophylactic or therapeutic thyroidectomy call the current recommendations for age at thyroidectomy into question.

METHODS

Sixteen family members underwent thyroidectomy, for which clinical, laboratory, and pathological data were analyzed. A literature review of RET codon 609 mutations was carried out.

RESULTS

Data were collected from 16 patients from this 38-member kindred. None of these affected members had pheochromocytoma, and one had a parathyroid adenoma. Nine of 16 patients had MTC (mean age 44.7 years, range 29-59 years) and elevated basal calcitonin levels; 6 of these 9 had lymph node metastases. Two patients had C-cell hyperplasia (CCH) at ages 18 and 37 years, and five patients had normal thyroid pathology (mean age 16 years, range 5-37 years). In the literature, a family with C609Y mutation was reported, with 15 members having MTC (mean age 42 years, range 21-59 years), and 6 with CCH (mean age 24 years, range 15-37 years).

CONCLUSION

The youngest patient with C609Y RET mutation and MTC was 21 years old, and the youngest patient with CCH was 15 years old at diagnosis. These data suggest that patients with RET C609Y mutations can delay thyroidectomy until 10-15 years of age, with annual calcitonin screening prior to thyroidectomy.

A new germline point mutation in Ret exon 8 (cys515ser) in a family with medullary thyroid carcinoma

BACKGROUND

A novel Cys-Ser Ret germline point mutation in a 58-year-old woman with bilateral medullary thyroid carcinoma (MTC) prompted us to perform genetic analysis of the family and evaluate the biological consequences of such a mutation.

METHODS

Ret analysis by direct sequencing was performed in five family members. The biological activity and biochemical properties of the Ret- Cys515Ser mutant were analyzed in NIH-3T3 cells.

RESULTS

The proband's son, age 35, had the Ret- Cys515Ser mutation and the L769 CTT/CTG exon 13 polymorphic variant, which was also found in his father. Clinical evaluation of the son also revealed bilateral multifocal microscopic MTC and papillary thyroid carcinoma (PTC). In vitro and in vivo analysis indicated ligand-independent activation of the Ret-Cys515Ser mutant due to aberrant disulfide homodimerization, increased mitogenic activity, and ability to induce anchorage-independent growth in NIH-3T3 cells in comparison to wild-type Ret, suggesting a possible role of Cys515Ser in tumor development.

CONCLUSIONS

The Cys515Ser mutation adds to cysteine substitution groups that have been described in association with MTC. Our data also highlight the importance of performing a complete genetic analysis in patients who present with MTC.

A unique RET EXON 11 (G691S) polymorphism in an Indian patient with a collision tumor of the thyroid

Background

Collision tumors of the thyroid are rare, with occasional reports dealing with their genetic analysis.

Case presentation

A 59 year old lady presented with a neck mass, associated with hoarseness of voice of 5 years duration. Radiological examination revealed nodular masses in the left lobe of her thyroid, along with one in the isthmus, extending into the right lobe and associated with enlarged neck nodes. FNAC from the left thyroid showed features of medullary carcinoma. On total thyroidectomy, 2 distinct tumor nodules were identified in the left lobe with another in the isthmus, showing features of medullary carcinoma (MTC), papillary carcinoma and follicular variant of papillary carcinoma, respectively, accompanied with nodal metastasis. Subsequently, she underwent radioablation. RET gene analysis of the patient, her 2 daughters and a grandson revealed a unique G691S polymorphism on Exon 11.

Conclusion

This unique case of a collision tumor of thyroid, including component of an MTC deals with the value of RET gene analysis and therapeutic implications in the index case and in family members.

Solitary fibrous tumor of the thyroid gland

Solitary fibrous tumor (SFT) is a rare spindle-cell neoplasm more commonly involving the pleura, but recognized also in other tissues. Nineteen patients with SFT arising from the thyroid gland have been reported in the literature. The present report reviews these cases and discusses epidemiology, etio-pathogenesis, clinical-pathologic characteristics, differential diagnosis, therapy, and prognosis of thyroid SFT.

Value of routine measurement of serum calcitonin concentrations in patients with nodular thyroid disease: A multicenter study

BACKGROUND

The routine measurement of serum calcitonin (CT) has been proposed for patients with nodular thyroid disease (NTD), to detect unsuspected medullary thyroid carcinoma (MTC) before surgery.

OBJECTIVE

To assess the prevalence of hypercalcitoninemia and MTC in NTD patients; to compare the ability of CT measurement and fine needle aspiration cytology (FNAC) to predict MTC; to identify age groups of NTD patients who should be better candidates than others to undergo routine measurement of CT.

PATIENTS AND METHODS

1425 consecutive patients, referred from April 1, 2003, through March 31, 2004, to four Italian endocrine centers due to NTD, were grouped depending on age, and underwent basal and, in some cases, pentagastrin (Pg)-stimulated CT measurement, FNAC and, when indicated, surgery. Serum CT concentrations were measured by an immunoluminometric assay (ILMA).

RESULTS

Hypercalcitoninemia was found in 23 out of 1425 patients. MTC was discovered in 9 patients, all >40 yr old and showing high CT levels. Sensitivity of basal and Pg-stimulated CT to predict MTC before surgery was 100% for both tests, whereas specificity was 95 and 93%, respectively. CT specificity reached 100% when a cutoff value of 20 pg/ml was taken. FNAC showed an overall 86% sensitivity. When >10 mm MTC nodules were considered, FNAC sensitivity approached 100%. On the contrary, a correct cytological diagnosis was obtained in only one out of five patients with <10 mm MTC nodules (microMTC); in one patient with histologically proved microMTC, FNAC even demonstrated a benign lesion. Hypercalcitoninemia or MTC were associated with chronic thyroiditis in 30 or 33% of cases, respectively. C-cell hyperplasia was found in 57% of hypercalcitoninemic patients without MTC.

CONCLUSIONS

Basal CT measurement detects elevated CT values in 1.6% of NTD patients. Although CT is not a specific marker of MTC, its routine measurement represents a useful tool in the pre-operative evaluation of NTD patients, particularly those >40 yr old presenting with nodules <10 mm, even when FNAC does not show malignant features. To our knowledge, this is the first trial using ILMA to assess the ability of pre-operative CT measurement to predict MTC in a large series of NTD patients.

RET tyrosine kinase signaling in development and cancer

The variety of diseases caused by mutations in RET receptor tyrosine kinase provides a classic example of phenotypic heterogeneity. Gain-of-function mutations of RET are associated with human cancer. Gene rearrangements juxtaposing the tyrosine kinase domain to heterologous gene partners have been found in sporadic papillary carcinomas of the thyroid (PTC). These rearrangements generate chimeric RET/PTC oncogenes. In the germline, point mutations of RET are responsible for multiple endocrine neoplasia type 2 (MEN 2A and 2B) and familial medullary thyroid carcinoma (FMTC). Both MEN 2 mutations and PTC gene rearrangements potentiate the intrinsic tyrosine kinase activity of RET and, ultimately, activate the RET downstream targets. Loss-of-function mutations of RET cause Hirschsprung's disease (HSCR) or colonic aganglionosis. A deeper understanding of the molecular signaling of normal versus abnormal RET activity in cancer will enable the development of potential new treatments for patients with sporadic and inherited thyroid cancer or MEN 2 syndrome. We now review the role and mechanisms of RET signaling in development and carcinogenesis.

The oncogenic activity of RET point mutants for follicular thyroid cells may account for the occurrence of papillary thyroid carcinoma in patients affected by familial medullary thyroid carcinoma

Activating germ-line point mutations in the RET receptor are responsible for multiple endocrine neoplasia type 2-associated medullary thyroid carcinoma (MTC), whereas somatic RET rearrangements are prevalent in papillary thyroid carcinomas (PTCs). Some rare kindreds, carrying point mutations in RET, are affected by both cancer types, suggesting that, under specific circumstances, point mutations in RET can drive the generation of PTC. Here we describe a family whose siblings, affected by both PTC and MTC, carried a germ-line point mutation in the RET extracellular domain, converting cysteine 634 into serine. We tested on thyroid follicular cells the transforming activity of RET(C634S), RET(K603Q), another mutant identified in a kindred with both PTC and MTC, RET(C634R) a commonly isolated allele in MEN2A, RET(M918T) responsible for MEN2B and also identified in kindreds with both PTC and MTC, and RET/PTC1 the rearranged oncogene that characterizes bona fide PTC in patients without MTC. We show that the various RET point mutants, but not wild-type RET, scored constitutive kinase activity and exerted mitogenic effects for thyroid PC Cl 3 cells, albeit at significantly lower levels compared to RET/PTC1. The low mitogenic activity of RET point mutants paralleled their reduced kinase activity compared to RET/PTC. Furthermore, RET point mutants maintained a protein domain, the intracellular juxtamembrane domain, that exerted negative effects on the mitogenic activity. In conclusion, RET point mutants can behave as dominant oncogenes for thyroid follicular cells. Their transforming activity, however, is rather modest, providing a possible explanation for the rare association of MTC with PTC.