Serum calcitonin negative medullary thyroid carcinoma: a systematic review of the literature

Diagnostic Performance of Preoperative Calcitonin and Procalcitonin Tests for Differential Diagnosis of Medullary Thyroid Cancer

Medullary thyroid cancer (MTC) shows a relatively poor prognosis among thyroid cancers. Though calcitonin has been used as a diagnostic marker for MTC, it has disadvantages including poor sample stability and discrepancies among results by assay. This study aimed to compare the usefulness of preoperative calcitonin and procalcitonin (PCT) in the diagnosis of MTC. Serum calcitonin and PCT levels were measured before thyroidectomy from MTC (n = 23) and other types of thyroid cancers in patients (n = 1308). Diagnostic performances of calcitonin and PCT for discerning MTC were estimated. In a multivariate analysis, preoperative calcitonin level was independently associated with the diagnosis of MTC, whereas PCT was not. Calcitonin and PCT, respectively, exhibited area under the curve values of 0.997 and 0.979 for the diagnosis of MTC, without significant differences. For calcitonin, the sensitivity, specificity, and positive and negative predictive values were 0.957, 0.992, 0.688, and 0.999, respectively, at a cut-off of 7.2 pg/mL. The corresponding values for PCT were 0.913, 0.995, 0.778, and 0.998 at a cut-off of 0.19 ng/mL. Preoperative calcitonin and PCT showed similar diagnostic utility for MTC. Depending on the patient's clinical status and laboratory environment, these tests can be used as complementary methods for detecting MTC.

Theranostics of Thyroid Cancer

Molecular imaging is pivotal in evaluating and managing patients with different thyroid cancer histotypes. The existing, pathology-based, risk stratification systems can be usefully refined, by incorporating tumor-specific molecular and molecular imaging biomarkers with theranostic value, allowing patient-specific treatment decisions. Molecular imaging with different radioactive iodine isotopes (ie, I131, I123, I124) is a central component of differentiated carcinoma (DTC)'s risk stratification while [18F]F-fluorodeoxyglucose ([18F]FDG) PET/CT is interrogated about disease aggressiveness and presence of distant metastases. Moreover, it is particularly useful to assess and risk-stratify patients with radioiodine-refractory DTC, poorly differentiated, and anaplastic thyroid cancers. [18F]F-dihydroxyphenylalanine (6-[18F]FDOPA) PET/CT is the most specific and accurate molecular imaging procedure for patients with medullary thyroid cancer (MTC), a neuroendocrine tumor derived from thyroid C-cells. In addition, [18F]FDG PET/CT can be used in patients with more aggressive clinical or biochemical (ie, serum markers levels and kinetics) MTC phenotypes. In addition to conventional radioiodine therapy for DTC, new redifferentiation strategies are now available to restore uptake in radioiodine-refractory DTC. Moreover, peptide receptor theranostics showed promising results in patients with advanced and metastatic radioiodine-refractory DTC and MTC, respectively. The current appropriate role and future perspectives of molecular imaging and theranostics in thyroid cancer are discussed in our present review.

Update on Calcitonin Screening for Medullary Thyroid Carcinoma and the Results of a Retrospective Analysis of 12,984 Patients with Thyroid Nodules

BACKGROUND

We provide an update on calcitonin (Ctn) screening for the early detection of medullary thyroid carcinoma (MTC) and present the results of a large single-center analysis evaluating sex-specific cut-off-levels and long-term courses.

METHODS

A total of 12,984 consecutive adult patients (20.1% male and 79.9% female) with thyroid nodules who had undergone routine Ctn measurement were retrospectively analyzed. Patients with confirmed suspicious Ctn values were referred for surgery.

RESULTS

Ctn measurements were elevated in 207 (1.6%) patients, with values below twice the sex-specific reference limit in 82% of these cases. Further clarification was possible in 124/207 cases, of which MTC could be ruled out in 108 cases. Histopathological assessment confirmed MTC in 16/12,984 patients.

CONCLUSIONS

Our extrapolated MTC prevalence of 0.14% is significantly lower than that described in early international screening studies. The stimulation test can usually be dispensable when using a decision-making concept based on sex-specific basal Ctn cut-off values. Ctn screening is recommended even in patients with very small thyroid nodules. High quality standards in pre-analytics, laboratory measurements, and the interpretation of data must be ensured, as well as close interdisciplinary cooperation between medical disciplines.

Diagnostic tests for medullary thyroid carcinoma: an umbrella review

PURPOSE

To summarize the more robust evidence about the performance of tools useful for diagnosis of medullary thyroid carcinoma (MTC) such as calcitonin (Ctn) and other circulating markers, ultrasound (US), fine-needle aspiration (FNA), and other imaging procedures.

METHODS

This systematic review of systematic reviews was carried out according to a predefined protocol. A search string was created. An electronical comprehensive search of literature was performed on December 2022. Quality assessment of eligible systematic reviews was performed and main findings were described.

RESULTS

Twenty-three systematic reviews were included and several findings were achieved. Ctn is the most reliable diagnostic marker of MTC with no evidence of improvement with stimulation test. CEA doubling time is more reliable than Ctn in identifying MTC with poorer prognosis. US sensitivity is suboptimal in MTC and only just over half of cases are at high risk according to Thyroid Imaging And Reporting Data Systems. Cytology can correctly detect MTC in just over half of cases and measuring Ctn in washout fluid from FNA is necessary. PET/CT is useful for detecting recurrent MTC.

CONCLUSIONS

Future guidelines of both thyroid nodule management and MTC diagnosis should consider these evidence-based data.

Other markers of medullary thyroid cancer, not only calcitonin

BACKGROUND

Medullary thyroid cancer (MTC) is a rare neuroendocrine tumor originating from parafollicular C-cells. It represents 2% of all thyroid malignancies and 0.4-1.4% of all thyroid nodules. MTC has a variable clinical course, with complete remission often difficult to achieve. An early diagnosis is still crucial in MTC management, enabling a radical surgical treatment, the only chance for curing the patient. Calcitonin (Ct) is a very sensitive MTC tumor marker in patients with thyroid nodules, although Ct-negative MTCs have been described, but not all clinical guidelines recommend the Ct routine measurement in thyroid nodules because of the absolute low prevalence of MTC in the general population and the consequent scarce positive predictive value of Ct. Moreover, the specificity of moderately high Ct levels is not high. Thus, the scientific community has been investigating the possible role of other tumor markers for MTC diagnosis and prognosis.

AIM OF THE REVIEW

The present review is an attempt to summarize the knowledge available today on the role of other serum markers for MTC alternative to Ct.

CONCLUSIONS

At present, literature data does not seem solid enough yet to establish effective flowcharts in evaluating a thyroid nodule for MTC, involving alternative serum markers, particularly in cases of moderately high CT levels. MTC is a rare diagnosis in thyroid nodules, and this makes the evaluation of any tumor serum marker accuracy problematic. More extensive and prospective studies are needed to shed more light on this intriguing challenge.

Evolution of thyroid cancer biomarkers: from laboratory test to patients’ clinical management

Over the past three decades, laboratory medicine has significantly evolved thanks to technological advances made possible by new materials and evidence. Clinicians’ ongoing requests for powerful, rapid, and minimally invasive tests has led manufacturers to develop rapid, accurate, and sensitive tests that can increase diagnostic accuracy and improve follow-up, bringing laboratory medicine ever closer to personalized medicine. The aim of this study was to critically review the main problems of the current Tg and CT biomarkers for the diagnosis/monitoring of DTC and MTC, respectively, and to identify the advantages and challenges of using the new laboratory biomarkers in the clinical management of patients with differentiated and medullary thyroid cancer. Insufficient harmonization of Tg and CT assays and lack of interchangeability of laboratory results and cutoff values pose challenges for comparability and standardization of procedures and methods. New diagnostic and monitoring approaches such as PCT or the Tg doubling time have proven to be effective. Close collaboration between clinicians and laboratory specialists remains essential to translate the advantages and limitations of current assays into appropriate clinical interpretation criteria. Over the years, the journal Clinical Chemistry and Laboratory Medicine (CCLM) has taken many steps to develop advanced research and technology in the diagnosis and monitoring of tumor cancer and to help clinicians translate it into clinical practice.

The dilemma of routine testing for calcitonin thyroid nodule's patients to detect or exclude medullary carcinoma: one single negative test should be valuable as rule-out strategy to avoid further calcitonin measurements over time

PURPOSE

While calcitonin (CT) measurement is recognized as the most accurate tool to diagnose medullary thyroid carcinoma (MTC), its routine use in patients with thyroid nodule (TN) is not universally accepted. The present study raised the question whether a TN patient with an initial normal CT can have suspicious CT levels (i.e., at least >20 pg/ml) later during his follow-up.

METHODS

The historical database of our institution was searched to select TN patients undergone multiple CT tests, having an initial normal CT, and clinically followed up for years. The event of a CT above 20 pg/ml (mild-to-moderate suspicion) and 100 pg/ml (high suspicion) was searched in the follow-up of the included patients.

RESULTS

According to the study design, the study sample encompassed 170 patients (131 female, 39 male) with initial CT value ≤10 pg/ml. On the first CT test, patients were 54.8 years and median CT was 2.1 pg/ml in both females and males. Over a period of 14.5 years and a median clinical follow-up of patients of 53.0 (23.9-102.5) months, MTC could be excluded by histology or cytology in 109 (64%) and clinically in the remaining ones. On the follow-up over time, no patients had CT >20 pg/ml and only two cases had CT just above 10 pg/ml.

CONCLUSION

According to the present results, one single CT testing with normal value could be reasonably used as a rule-out strategy in patients with TN to avoid further CT measurements.

Small-Cell Malignancies of Thyroid: Challenge Solved?

"Small-cell malignancies of thyroid" is an unsolved dilemma. This term represents an umbrella terminology in thyroid, encompassing for a small group of tumors in which some of them are well-recognized tumors like medullary thyroid carcinoma, poorly differentiated thyroid carcinoma, and primary thyroid lymphomas and teratoma, whereas the remaining are less known as primary neuroendocrine carcinoma of thyroid, primary extraskeletal Ewing family tumors, and adamantinoma-like Ewing sarcoma. When the issue comes to evaluate a cytological sample predominantly composed of small-cell morphology, metastatic small-cell carcinomas to thyroid also should be excluded. In this review, our group focused on the main cytomorphological and clinical clues of each entity that help to set up a correct differential diagnosis. The literature discussions were also included for the entities that are not yet recognized by the mother publication WHO. A key point of the issue's simple algorithm based on FNAC with small-cell morphology of thyroid was suggested by the authors.

Oncologic outcomes of calcitonin-negative medullary thyroid carcinoma

OBJECTIVE

Calcitonin (Ct)-negative medullary thyroid carcinoma (MTC) is a rare neuroendocrine tumor. This study aimed to clarify its incidence, clinicopathologic characteristics, management, and treatment outcome.

METHODS

We retrospectively analyzed data of patients with primary MTC. Patients were divided into two groups according to the preoperative serum Ct level (Ct-negative and Ct-positive). The demographic, pathologic, and molecular characteristics, and treatment outcomes were compared between the two groups. In the Ct-negative group, we analyzed the association between the operation type and treatment outcome.

RESULTS

Of the total 312 patients, 24 were diagnosed with Ct-negative MTC. The rate of lymph node metastasis was significantly higher in the Ct-positive than in the Ct-negative group (47.9% vs. 0%, p<0.001). The proportion of patients with Ki-67 ≤10% was significantly higher in the Ct-negative than in the Ct-positive group (87.5% vs. 38.2%, p<0.001). Excellent response was achieved by 91.7% and 34.7% of patients in the Ct-negative and Ct-positive groups, respectively (p<0.001). In the Ct-negative group, excellent response was achieved by all female patients, but only 50% of male patients.

CONCLUSIONS

Ct-negative MTC is rare and unlikely to develop lymph node metastasis. Unilateral lobectomy tends to provide a satisfactory chance of excellent response; however, this requires further validation.

Ca19.9 Positivity and Doubling Time Are Prognostic Factors of Mortality in Patients with Advanced Medullary Thyroid Cancer with No Evidence of Structural Disease Progression According to Response Evaluation Criteria in Solid Tumors

Background: Serum Ca19.9 positivity is a prognostic factor for mortality in patients with advanced medullary thyroid cancer (aMTC), independently from calcitonin doubling time (DT). However, it is unknown whether aMTC patients who become positive for Ca19.9 also have progressive disease (PD) according to response evaluation criteria in solid tumors (RECIST) and whether Ca19.9 DT has a role in the management of aMTC patients. The aims of this study were to evaluate whether in aMTC, when serum Ca19.9 becomes positive, PD develops, and to determine the role of Ca19.9 DT in predicting mortality and PD. Patients and Methods: Serum Ca19.9 was periodically measured in 107 aMTC patients, and the DTs were calculated. Restaging of the disease was radiologically performed in 104 of 107 patients and PD was evaluated according to RECIST. Results: At the end of follow-up, 25 of 107 patients were Ca19.9 positive and PD was identified in 30 of 104 patients. No significant association was found between Ca19.9 positivity and PD, while there was a significant association between Ca19.9 positivity and mortality (p < 0.0001). Ca19.9 DTs <6 months and <1 year were not associated with PD but were associated with mortality (p < 0.0001 and p < 0.0001, respectively). In particular, 3 patients who had a Ca19.9 DT <6 months with no evidence of PD according to RECIST died of their disease after 6, 5, and 3 months, respectively. Conclusions: Serum Ca19.9 positivity and DTs <6 months and <1 year are prognostic factors for mortality but not for PD. Serum Ca19.9 positivity and DTs <6 months and <1 year should be considered in the decision-making process of whether to initiate systemic therapy even if there is no evidence of PD according to RECIST.

Circulating pro-gastrin releasing peptide (ProGRP) in patients with medullary thyroid carcinoma

OBJECTIVES

Serum calcitonin (CT) is pivotal in medullary thyroid cancer (MTC) management. Recently, progastrin releasing peptide (ProGRP) has been proposed as a candidate complementary tumor marker of MTC. As current data are sparse our study was undertaken to evaluate the distribution of ProGRP in patients with MTC and its relationship with the tumor burden. Additionally, serial measurement of CT, carcinoembryonic antigen (CEA) and ProGRP was evaluated in three patients undergoing tyrosine kinase inhibitors (TKI).

METHODS

Seventy-eight, 125 and 62 sera from patients with MTC, non-medullary malignant and benign thyroid diseases were collected, respectively. ProGRP measurement was performed by Elecsys^® assays on Cobas e601 platform (Roche Diagnostics).

RESULTS

Significantly higher ProGRP levels were found in MTC compared to non-MTC patients. Among MTC patients ProGRP levels accurately discriminate patients with active from those with cured disease and, respectively, patients with loco-regional active disease from those with distant metastasis. Finally, ProGRP performed better than CT and CEA in monitoring the response to TKI therapy in three patients monitored serially.

CONCLUSIONS

Serum ProGRP is promising as a complementary tumor marker in MTC patients. Further studies will be required, mainly focused on monitoring ProGRP during TKI treatment for early detection of resistance and assessing its usefulness to avoid the observed false positive fluctuations that occur with CT and carcinoembryonic antigen.

Diagnostic Utility of INSM1 in Medullary Thyroid Carcinoma

Insulinoma-associated protein 1 (INSM1) is shown to be an excellent marker for neuroendocrine differentiation. However, the diagnostic utility of INSM1 in medullary thyroid carcinoma (MTC) has not yet been extensively investigated. INSM1 staining was performed on 21 MTCs, 7 MTC mimickers (including 3 papillary carcinomas, 2 poorly differentiated carcinomas, 1 follicular adenoma, and 1 nodular plasma cell hyperplasia), and 3 cases of C-cell hyperplasia. INSM1 staining of these cases was compared with the traditional MTC markers including calcitonin (CT), monoclonal carcinoembryonic antigen (mCEA), chromogranin A (CgA), and synaptophysin (Syn). The H-score was generated using the QuPath program, an open-source image analysis software. All 21 MTC cases and 3 C-cell hyperplasia cases were positive for all markers. The MTC mimickers were entirely negative for INSM1. INSM1 and Syn displayed, more consistently, high expression with minimal variability than CgA that showed a wide range of expression with significant variability. mCEA and CT exhibited mostly a high expression with some variability. Being a nuclear stain, interpretation was easier with INSM1 compared to other cytoplasmic markers. INSM1 is an excellent marker for neuroendocrine differentiation, entirely applicable in the diagnosis of MTC and C-cell hyperplasia with high sensitivity and specificity. In comparison with the traditional MTC markers, INSM1 is unique in the crisp nuclear staining pattern with a consistent, diffuse, and strong expression. INSM1 can be potentially combined with CT or mCEA as a dual stain, especially when the lesional tissue is limited for a panel of immunostains.

Calcitonin-Negative Neuroendocrine Carcinoma of the Thyroid Gland: Case Report and Literature Review

Calcitonin-negative neuroendocrine tumor (CNNET) of the thyroid is an extremely rare entity. In some of the previously reported cases within the literature, the terms “atypical medullary thyroid carcinoma,” “calcitonin-free oat cell carcinoma,” and “a distinct clinical entity” were applied to NETs without definitive evidence of calcitonin production. In the English-language literature, not only are there only few reported cases of CNNET, but the criteria for diagnosis in these cases are also controversial. Most of the current published cases were also treated surgically for local disease. We describe a case of NET of the thyroid with calcitonin, chromogranin A and thyroglobulin negativity, synaptophysin and TTF-1 positivity, and a high Ki-67 proliferation index with metastases in the cervical region as well as mediastinal adenopathies. This case was considered an unresectable thyroid carcinoma, and chemotherapy including cisplatin and etoposide was started as neoadjuvant treatment at the department of medical oncology. Total thyroidectomy plus bilateral and central cervical dissection was performed, and the patient underwent 2 cycles of adjuvant radiotherapy. Currently, the patient's ¹⁸F-FDG-PET/CT findings show a complete response 17 months after diagnosis. In conclusion, CNNET of the thyroid is very rare and there is limited evidence regarding treatment in patients with metastases. Chemotherapy including cisplatin and etoposide as well as early aggressive surgical resection appears to positively impact patients' survival.

Basal and Calcium-Stimulated Procalcitonin for the Diagnosis of Medullary Thyroid Cancers: Lights and Shadows

BACKGROUND

Procalcitonin (proCt) was recently proposed as an alternative or in addition to calcitonin (Ct) in medullary thyroid cancer (MTC) diagnostics.

METHODS

Serum basal Ct (bCt) and proCt (bproCt) levels were measured before surgery from a consecutive series of patients with (n=43) and without (n=75) MTC, retrospectively collected in Padua. Serum bproCt, bCt and stimulated proCt and Ct (sproCt and sCt) were measured in another consecutive series of 33 patients seen at three tertiary-level institutions undergoing a calcium stimulation test prior to surgery, 20 of them with a final diagnosis of MTC, and 13 with non-MTC nodular disease.

RESULTS

Median bproCt levels were higher in MTC than in non-MTC. A positive correlation was found for bproCt with bCt (P<0.01, R² = 0.75), and with tumor size (P<0.01, R² = 0.39). The cut-off for bproCt differentiating between MTC and non-MTC patients was >0.07 ng/ml (sensitivity: 85.7%, specificity: 98.9%, positive predictive value [PPV]: 98.2%, negative predictive value [NPV]: 90.6%, P<0.01). While bproCt was >0.07 ng/ml in 38/39 (97.4%) patients with MTC >10 mm, it was above said cut-off only in 15/23 (65.2%) patients with tumors ≤10 mm. A sproCt >0.19 ng/ml was able to identify MTC [sensitivity: 90.0%, specificity:100.0%, PPV: 100.0%, NPV: 86.7% (P<0.01)].

CONCLUSIONS

Our data suggest that bproCt can be a good adjunct to Ct for MTC diagnostic purposes. In consideration of its high specificity, it can be used in combination with Ct in MTC diagnostics, particularly in the case of mildly elevated basal Ct levels.

Unexpected Pathogenic RET p.V804M Variant Leads to the Clinical Diagnosis and Management of Medullary Thyroid Carcinoma

Patient: Female, 62-year-old

Final Diagnosis: Medullary thyroid microcarcinoma

Symptoms: No pain or swelling in her neck • no dysphagia or odynophagia • no changes in voice

Medication: —

Clinical Procedure: Genetic analysis

Specialty: Genetics

Clinical relevance of 18F-FDG PET/CT in the postoperative follow-up of patients with history of medullary thyroid cancer

BACKGROUND

The aim of the study was evaluation of 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography with computed tomography (PET/CT) in the detection of active disease in the patients with suspected recurrence of the medullary thyroid carcinoma (MTC).

PATIENTS AND METHODS

18F-FDG PET/CT investigation was performed in 67 patients, investigated from 2010 to 2019. _ Follow up was performed from 6 to 116 months after surgery (median 16.5 months, x± SD = 29±28.9 months). Twenty five of 67 patients underwent 99mTc-dimercaptosuccinic acid (99mTc-DMSA) scintigraphy, 11 underwent somatostatin receptor scintigraphy (SRS) with 99mTc-HYNIC TOC while 11 123I-metaiodobenzylguanidine (MIBG) scintigraphy.

RESULTS

From 67 patients, 35 (52.2%) had true positive 18F-FDG PET/CT findings (TP). Average maximal standardized uptake value (SUVmax) for all TP lesions was 5.01+3.6. In 25 (37.3%) patients findings were true negative (TN). Four (6%) patients had false positive (FP) findings while three (4.5%) were false negative (FN). Thus, sensitivity of the 18F-FDG PET/ CT was 92.11%, specificity 86.21%, positive predictive value 89.74%, negative predictive value 89.29% and accuracy 89.55%. In 27 patients (40%) 18F-FDG PET/CT finding influenced further management of the patient.

CONCLUSIONS

18F-FDG PET/CT has high accuracy in the detection of metastases/recurrences of MTC in patients after thyroidectomy as well as in evaluation and the appropriate choice of the therapy.

Medullary Thyroid Carcinoma With Elevated Serum CEA and Normal Serum Calcitonin After Surgery: A Case Report and Literature Review

Background

Medullary thyroid carcinoma (MTC) is a relatively rare malignant tumor subtype originated the parafollicular C cells of the thyroid gland, producing tumor markers including calcitonin (Ctn), carcinoembryonic antigen (CEA), and chromogranin A. Preoperative serum Ctn and CEA value is important for assessing disease burden, postoperative serum Ctn and CEA can help to determine whether there are recurrence and distant metastasis.

Case Presentation

We report a rare case in which the CEA level continued to increase and the Ctn value was normal after total thyroidectomy and central lymph node dissection in a MTC patient. The patient was asymptomatic during one and half year follow-up until lateral lymph node metastasis was revealed. However, the CEA level raised again after lateral neck lymph node dissection and bone metastases were found by 18F-FDG PET-CT.

Conclusion

This case reminded us the recurrence of MTC should be suspected for patients with simply elevated CEA after surgery for MTC. Differential diagnosis of other malignant tumors and timely lymph node biopsy is of great significance for management.

Clinical performance of calcitonin and procalcitonin Elecsys® immunoassays in patients with medullary thyroid carcinoma

Objectives

Medullary thyroid carcinoma (MTC) is caused by a malignant transformation in the parafollicular C-cells of the thyroid, where calcitonin (CT) is released. Nowadays, CT is the main tumor marker used in the diagnosis and follow-up of MTC patients. Nonetheless, procalcitonin (PCT) has recently been proposed as a useful complementary/alternative biomarker in MTC. Our aims were to investigate the diagnostic performance of CT and PCT and their combination in the differential diagnosis between active and inactive MTC and between MTC and non-MTC thyroid diseases, respectively.

Methods

Serum samples were collected from 16 patients with active (i.e. primary tumour before surgery or post-surgical recurrent disease) and 23 with inactive (i.e. complete remission) MTC, 125 patients with non-MTC benign thyroid disease and 62 patients with non-MTC thyroid cancers, respectively. Elecsys® CT and PCT measurements were simultaneously performed on the Cobas e601 platform (Roche Diagnostics, Rotkreutz, Switzerland).

Results

Both CT and PCT median values in active MTC (94 pmol/L and 1.17 ng/mL, respectively) were significantly higher compared with inactive MTC (0.28 and 0.06) and either benign (0.37 and 0.06) or malignant (0.28 and 0.06) non-MTC. Undetectable PCT was found in five non-MTC patients with false positive CT results.

Conclusions

Elecsys® PCT assay is a highly sensitive and specific alternative MTC marker. At the very least it appears useful in patients with positive CT results as negative PCT values securely exclude active MTC. The availability of both markers on the same automated platform facilitates reflex or reflective strategies to refine the laboratory diagnosis.

Characterization of "suspicious for malignancy" for non-papillary carcinoma diagnoses on thyroid fine-needle aspiration

INTRODUCTION

To evaluate the incidence, risk of malignancy, and management of "suspicious for malignancy" (SFM) for non-papillary carcinoma diagnoses according to The Bethesda System for Reporting Thyroid Cytopathology (TBSRTC).

MATERIALS AND METHODS

A retrospective search was performed for all thyroid fine-needle aspirations (FNAs) with an SFM diagnosis in the electronic Pathology database at The Johns Hopkins Hospital from 2000 to 2019. During this period, a total of 644 cases were diagnosed as SFM. Of these, 55 cases of "suspicious for non-papillary thyroid carcinoma" (SNPTC) were identified. These 55 cases were then compared with 65 random cases of "suspicious for papillary thyroid carcinomas" (SPTC) diagnoses as a control group.

RESULTS

The SNPTC subgroup consisted of 28 cases of "suspicious for medullary thyroid carcinoma" (SMTC) (50.91%), 4 cases of "suspicious for metastasis" (SMET) (7.27%), 3 cases of "suspicious for malignant lymphoma" (SML) (5.45%), 2 cases of "suspicious for poorly-differentiated thyroid carcinoma" (SPDC) (3.64%), and 18 cases of "suspicious for malignancy, not otherwise specified" (SNOS) (32.73%). When compared to SPTC, SNPTC patients' average age was older (P = 0.004). Ancillary studies assisted in diagnosing SNPTC more so than SPTC (P < 0.001). Immunohistochemical studies were performed for 11 cases, molecular studies for 6 cases, and needle rinse calcitonin level for 1 case. When correlated with surgical follow-ups, the risk of malignancy (ROM) was 91.18% for SNPTC compared to 93.75 for SPTC%.

CONCLUSIONS

SNPTC was rarely diagnosed when compared with SPTC. SMTC was the most commonly diagnosed SNPTC subgroup, followed by SNOS. The ROM of SNPTC was slightly lower than that of SPTC. Ancillary studies and previous clinical history, in addition to cytomorphology, was helpful when rendering the diagnosis of SNPTC.

Revisiting the genotype-phenotype correlation in children with medullary thyroid carcinoma: A report from the GPOH-MET registry

BACKGROUND

Medullary thyroid carcinomas (MTC) account for 3% to 5% of all thyroid cancers. In most cases, MTC is hereditary and occurs as part of the multiple endocrine neoplasia (MEN) type 2A and 2B syndromes. There is a strong genotype-phenotype correlation associated with the respective RET mutations, making risk-adapted management possible.

PROCEDURE

We report the prospectively collected data on children and adolescents of the multicenter nonrandomized German GPOH-MET registry. Children and adolescents with MTC and C-cell hyperplasia (CCH) were included.

RESULTS

From 1997 to June 2019, a total of 57 patients with MTC and 17 with CCH were reported. In patients with MTC, median follow-up was five years (range, 0-19) and median age at diagnosis 10 years (range, 0-17). Overall survival and event-free survival (EFS) were 87% and 52%, respectively. In total 96.4% of patients were affected by MEN2 syndromes, which was in 37/42 MEN2A and 3/28 MEN2B (M918T mutation) inherited. EFS in MEN2A was 78%, and in MEN2B 38% (P < 0.001). In multivariate analyses, lymph node (LN) status and postoperatively elevated calcitonin were significant prognostic factors for EFS. Notably, modest-risk mutation carriers presented with MTC at a rather young age, without raised calcitonin, and LN metastases.

CONCLUSIONS

Identification of children carrying de novo RET M918T mutations by means of the characteristic phenotype is crucial to detect MTC at an early stage, which will be associated with improved survival. As calcitonin levels may be false-negative and modest-risk mutation carriers present with a variable phenotype, particular attention should be paid to these children.

ProGRP AS A NOVEL BIOMARKER FOR THE DIFFERENTIAL DIAGNOSIS OF MEDULLARY THYROID CARCINOMA IN PATIENTS WITH THYROID NODULES

Objective: To investigate the release of progastrin-releasing peptide (ProGRP) in patients with thyroid nodules and the value of ProGRP in fine-needle aspirate washout fluid (FNA-ProGRP) in the differential diagnosis between medullary thyroid carcinoma (MTC) and non-MTC thyroid nodules. Methods: We investigated 2,446 healthy persons and 212 patients with 235 thyroid nodules. They were classified into healthy, nodular goiter, chronic thyroiditis, thyroid follicular neoplasm, papillary thyroid carcinoma, follicular thyroid carcinoma, and medullary thyroid carcinoma. The serum ProGRP and FNA-ProGRP were measured. Results: The serum ProGRP median concentration in MTC was 124.40 pg/mL, significantly higher than in other groups. The cutoff value of serum ProGRP was 68.30 pg/mL, leading to 53.85% sensitivity, 96.98% specificity, and 0.51 kappa value in MTC. The FNA-ProGRP median concentration in MTC nodules was 2,096.00 pg/mL, significantly higher than in other groups. A receiver operating characteristic analysis of MTC nodules and non-MTC nodules indicated that the cutoff value was 22.77 pg/mL, leading to 94.12% sensitivity, 98.27% specificity, and 0.85 kappa value. Conclusion: FNA-ProGRP measurement could be served as an ancillary method for the differential diagnosis between MTC and non-MTC thyroid nodules. Abbreviations: CEA = carcinoembryonic antigen; CT = calcitonin; FNAC = fine-needle aspiration cytology; FNA-CT = calcitonin in fine-needle aspirate washout fluid; FNA-ProGRP = ProGRP in fine-needle aspirate washout fluid; MTC = medullary thyroid carcinoma; ProGRP = progastrin-releasing peptide; SCLC = small-cell lung cancer; TM = tumor marker.

Calcitonin-negative medullary thyroid carcinoma: the 'triple-negative' phenotype

Calcitonin-negative medullary thyroid carcinoma is a rare, poorly understood primary neuroendocrine carcinoma of the thyroid characterised by classic medullary thyroid carcinoma morphology without raised serum calcitonin. A 24-year-old woman presented with a slow-growing, right-sided neck swelling. She underwent an ultrasound scan, cytopathological and histopathological examination, and tests for alternative diagnoses. The ultrasound showed a heterogeneous, hyperechoic nodule in the right thyroid lobe. Serum calcitonin was normal. Cytopathology and histopathology showed typical medullary thyroid carcinoma morphology but without calcitonin upon immunostaining and mRNA in situ hybridisation. A 'triple-negative' calcitonin-negative medullary thyroid carcinoma was diagnosed. A completion thyroidectomy with bilateral central lymph node dissection was performed. The patient remains well three-years post-surgery. When cytopathology suggests a medullary thyroid carcinoma, serum calcitonin, pro-calcitonin, carcinoembryonic antigen and calcitonin-gene-related peptide should be measured to identify cases of calcitonin-negative medullary thyroid carcinoma. They should also be measured post-treatment for monitoring purposes. This will aid future calcitonin-negative medullary thyroid carcinoma diagnoses and will inform prognostic stratification and influence treatment decisions.

Medullary thyroid carcinoma with double negative calcitonin and CEA: a case report and update of literature review

BACKGROUND

Medullary thyroid carcinoma is a malignant uncommon and aggressive tumour of the parafollicular C cells. In about 75% of cases it is sporadic while, in case of RET mutation, it is associated to multiple endocrine neoplasia type 2 (25% of cases). The biochemical features of medullary thyroid carcinoma include the production of calcitonin and carcinoembryogenic antigen. The above-mentioned features are useful in the diagnostic process as well as in the follow up and in the prognostication of the disease. Even if calcitonin elevation is strongly associated to MTC, it can also be found increased in many pathological different conditions as pregnancy, lactation, C-cells hyperplasia, autoimmune thyroiditis, end stage renal disease, lung and prostate cancer and several neuroendocrine tumours. Major medullary thyroid tumours are usually connected to high doses of circulating calcitonin, in fact non-secretory variants have hardly been described.

CASE PRESENTATION

We herein report the case of a 59 years old male, who had undergone total thyroidectomy for multinodular goiter with negative preoperative calcitonin, showing medullary thyroid carcinoma at definitive pathology. To the best of our knowledge, this is the first case documenting a non-secretory medullary thyroid carcinoma, with double negative markers at the time of diagnosis and at the relapse.

CONCLUSION

A Literature review underlining pathological hypothesis, differential diagnosis and alternative and innovative biomarkers to identify non-secretory medullary thyroid carcinoma was carried out.

Genetic analysis of a hereditary medullary thyroid carcinoma case with normal preoperative serum calcitonin levels

CONTEXT

Serum calcitonin is often elevated in medulla thyroid carcinoma (MTC) and thus serves as an indicator of primary and recurrent disease. However, there are MTC patients with normal Serum calcitonin and the underlying mechanisms are largely unknown.

CASE DESCRIPTION

A 48-year-old female patient presenting with a right anterior cervical mass was diagnosed with medullary carcinoma. She had elevated carcinoembryonic antigen (CEA) but normal Serum calcitonin levels. Next generation sequencing (NGS) of paired tumor and peripheral blood revealed a germline pathogenic RET mutation, indicating the hereditary nature of MTC in this patient. Two somatic loss-of-function mutations in DICER1 gene were also found, which we postulated to account for the normal calcitonin levels found in this patient. To our knowledge, this is the first report of a hereditary MTC case displaying a normal Serum calcitonin.

CONCLUSIONS

The case suggests NGS can be used in the diagnosis of hereditary MTC and exploring the reasons of normal Serum calcitonin in these patients.

An Unusual Case of Medullary Thyroid Carcinoma and A Revision of Current Literature

BACKGROUND

Medullary thyroid cancer (MTC) accounts for 5% of all thyroid cancers and occurs either sporadically or in a hereditary pattern. Routine calcitonin (CT) measurement is suggested for MTC screening in patients with nodular thyroid disease.

PATIENT FINDINGS

A 45 years-old woman incidentally discovered, with neck ultrasound, the presence of thyroid micronodules. Fine-needle aspiration (FNA) on thyroid prevailing nodule did not demonstrate cellular atypia. During follow-up, FNA was repeated on the previously analyzed nodule suspicious for Hürthle cell nodule suspicious for follicular neoplasm and on another hypoechoic right nodule which showed cellular atypia. CT was <2 pg/ml (normal values <18.2 pg/ml), anti-thyroid antibodies were positive and the patient showed a normal thyroid function. The patient also was diagnosed with primary hyperparathyroidism with an enlarged parathyroid gland behind the right thyroid lobe. Therefore, she underwent total thyroidectomy and a selective parathyroidectomy was performed. Histology showed an encapsulated microMTC (pT1aNxMx) associated with diffuse C-cell hyperplasia and lymphocytic thyroiditis. The neoplasm was positive for calcitonin and chromogranin A and negative for thyroglobulin. A right parathyroid adenoma was also diagnosed. One month after surgery basal and stimulated CT were <2 ng/ml. Genetic analysis did not reveal mutation of RET proto-oncogene. Twelve months after surgery, neck ultrasonography, chest and abdomen computed tomography did not demonstrated residual/recurrent disease with undetectable serum CT.

CONCLUSION

In the literature, few MTC cases with normal serum CT have been reported. Although MTC without elevated plasma CT is extremely rare, normal or low CT levels, do not entirely exclude this diagnosis.

Calcitonin negative Medullary Thyroid Carcinoma: a challenging diagnosis or a medical dilemma?

BACKGROUND

Medullary thyroid carcinoma is a neuroendocrine tumor belonging form a malignant growth of the thyroid parafollicular C-cells, representing from 1 to 10% of all thyroid cancer. The biochemical activity of medullary thyroid carcinoma includes the production of calcitonin and carcinoembryogenic antigen, which are sensitive tumor markers, facilitating the diagnosis, follow-up and prognostication. The diagnosis is reached through the identification of high basal calcitonin serum level or after pentagastrin stimulation test. Medullary thyroid carcinoma is able to produce other relevant biomarkers as procalcitonin, carcinoembryionic antigen and chromogranin A. In Literature are described few cases of medullary thyroid carcinoma without elevation of serum calcitonin, an extremely rare event. The aim of this study was to analyse the presentation, the main features and therapeutic management of medullary thyroid carcinoma associated with negative serum calcitonin levels.

METHODS

Using the PubMed database, a systematic review of the current Literature was carried out, up to February 2018. Finally, nineteen articles met our inclusion criteria and were selected according to the modified Newcastle-Ottawa scale.

RESULTS

Fourty-nine patients with definitive pathology confirming medullary thyroid carcinoma and with calcitonin serum level in the normal range were identified (24 female, 24 male and not reported gender in 1 case). Mean age was 51.7 years. Serum calcitonin levels were reported for 20 patients with a mean value of 8.66 pg/mL and a range of 0.8-38 pg/mL. Despite the low or undetectable calcitonin serum level, at immunochemistry in almost the half of the cases reported by the Authors, the tumors presented diffuse or focal positivity for calcitonin and carcinoembryionic antigen, while was reported a chromogranin A positivity in 41 of the 43 tested patients.

CONCLUSIONS

Calcitonin negative medullary thyroid carcinoma is an extremely rare pathology. The diagnosis and the surveillance is often challenging and delayed, due to the lack of elevation of serum markers as calcitonin and carcinoembryionic antigen. Further studies are needed, to better define options for management of non secretory medullary thyroid carcinoma and to identify new and reliable biomarkers associated to diagnosis and relapse of this medical dilemma.

Comprehensive evaluation of medullary thyroid carcinoma before surgery

BACKGROUND

Medullary thyroid carcinoma (MTC) is a rare disease, but it exhibits more aggressive behaviors. The aim of this study was to improve the diagnostic accuracy of MTC before surgery by analyzing the clinical and ultrasonic data of patients with MTC.

METHODS

The study included 71 patients (96 lesions) with histopathologically proven MTC between April 2011 and September 2016 in the Cancer Hospital of Chinese Academy of Medical Sciences and Peking Union Medical College. The clinical characteristics and sonographic findings were retrospectively reviewed and compared between the ultrasonic correct diagnosis group and the ultrasonic misdiagnosis group with the t test or Mann-Whitney U test for quantitative parameters and the χ test or Fisher exact test for qualitative parameters.

RESULTS

Compared with the ultrasonic correct diagnosis group, the proportion of the cystic change in the ultrasonic misdiagnosed group was high (25.0% vs. 4.2%), the uncircumscribed margin and irregular shape proportions were low (20.8%, 58.3% vs. 74.7%, 87.3%), calcification was relatively rare (20.8% vs. 56.3%), and rich vascularity was relatively rare (25.0% vs. 78.9%).

CONCLUSIONS

In the case of atypical MTC, such as cystic change, circumscribed margin, regular shape, no calcification, no rich vascularity, and normal cervical lymph nodes, MTC is easily misdiagnosed as benign by ultrasound. Therefore, ultrasound, cytology and serum calcitonin should be comprehensively evaluated for a preoperative diagnosis of MTC.

Serum calcitonin nadirs to undetectable levels within 1 month of curative surgery in medullary thyroid cancer

OBJECTIVE

Because serum calcitonin (CT) is a reliable marker of the presence, volume, and extent of disease in medullary thyroid cancer (MTC), both the ATA and NCCN guidelines use the 2-3 month post-operative CT value as the primary response to therapy variable that determines the type and intensity of follow up evaluations. We hypothesized that the calcitonin would nadir to undetectable levels within 1 month of a curative surgical procedure.

SUBJECTS AND METHODS

This retrospective review identified 105 patients with hereditary and sporadic MTC who had at least two serial basal CT measurements done in the first three months after primary surgery.

RESULTS

When evaluated one year after initial surgery, 42 patients (42/105, 40%) achieved an undetectable basal calcitonin level without additional therapies and 56 patients (56/84, 67%) demonstrated a CEA within the normal reference range. In patients destined to have an undetectable CT as the best response to initial therapy, the calcitonin was undetectable by 1 month after surgery in 97% (41/42 patients). Similarly, in patients destined to have a normalize their CEA, the CEA was within the reference range by 1 month post-operatively in 63% and by 6 months in 98%. By 6 months after curative initial surgery, 100% of patients had achieved a nadir undetectable calcitonin, 98% had reached the CEA nadir, and 97% had achieved normalization of both the calcitonin and CEA.

CONCLUSION

The 1 month CT value is a reliable marker of response to therapy that allows earlier risk stratification than the currently recommended 2-3 month CT measurement.

Study on the degradation rule of calcitonin in vitro in patients with medullary thyroid carcinoma

BACKGROUND

It was found that calcitonin in vitro can degrade rapidly whether in refrigeration or at room temperature, which increases the difficulty of accurate detecting of calcitonin greatly. This study was designed to solve this problem.

METHODS

Serum samples with increased calcitonin from patients with medullary thyroid carcinoma were collected and divided into refrigeration and room temperature group. Analyze the degradation rule of calcitonin in the two groups according to the time of blood draw (T0), the time of sample detection (Tx), and the concentration (y) measured at Tx.

RESULTS

The degradation rate of calcitonin was significantly different between the two storage conditions. The degradation has plateau stage and its concentration is associated with the original concentration. The degradation rule of the two groups can be expressed by the formula: y = -aln(x) + b. In the formula, b/a are constants associated with storage condition and gender. "x" is the time interval between blood draw and detection, that is, x = Tx - T0.

CONCLUSIONS

The significance of the presence of immunoreactive isoforms and fragments of calcitonin with different stability in patients with medullary thyroid carcinoma is unclear. To make the inspection report more accurate and reliable, maybe the inspection personnel should report both the instrumental and corrected result, and also indicate the correction formula on the inspection report.

Proteome profiles of different types of thyroid cancers

Proteomics profiling of tissue specimens representative for major types of thyroid cancers: papillary (classical and follicular variant), follicular, anaplastic and medullary, as well as benign follicular adenoma, was performed using shotgun LC-MS/MS approaches. A combination of Orbitrap and MALDI-TOF approach allowed to identify protein products of 3700 unique genes and revealed large differences between medullary, anaplastic and epithelium-derived differentiated cancers (papillary and follicular). Proteins characteristic for medullary and anaplastic cancers included factors associated with neuroendocrine functions and factors typically associated with advanced malignancies, respectively. Proteomes of different types of epithelium-derived differentiated cancers and follicular adenoma were compared using multi-enzyme LC-MS/MS approach, which revealed products of 4800 unique genes. A comparable overall similarity of follicular cancers to both variants of papillary cancers was found. Moreover, follicular adenoma showed higher overall similarity to follicular cancer than to either variant of papillary cancer. Proteins discriminating differentiated thyroid neoplasms included factors associated with lipid and hormone metabolism, regulation of gene expression and maintenance of DNA structure. Importantly, proteome data matched several features of transcriptome and metabolome profiles of thyroid cancers contributing to systems biology of this malignancy.

Procalcitonin measurement to screen medullary thyroid carcinoma: A prospective evaluation in a series of 2705 patients with thyroid nodules

BACKGROUND

To prospectively evaluate the role of procalcitonin (PCT) in screening of patients with thyroid nodules for medullary thyroid carcinoma (MTC).

MATERIALS AND METHODS

We measured PCT in 2705 patients with thyroid nodules referred to our centre between January 2011 and December 2017. Those with a positive PCT were operated after positive confirmatory tests such as fine-needle aspiration, measurement of calcitonin (CT) in serum and fine-needle aspiration washouts or CT stimulation testing. Patients with a negative PCT were operated based on the results of further diagnostics. The diagnostic performance of PCT was evaluated, and the best cut-off level was selected by ROC curve analysis.

RESULTS

Among 2705 patients, 9 with positive serum PCT (ie, above 0.1 μg/L) and 370 with negative PCT underwent thyroid surgery. MTC was histologically confirmed in all patients with positive PCT but not found in patients with negative PCT. Serum PCT levels were significantly higher in patients with MTC (median 0.64 μg/L, range 0.16-12.9 μg/L) than in those without (median 0.075 μg/L, range 0.075-0.16 μg/L; P < .0001). ROC curves were plotted to calculate the optimal PCT value separating patients with MTC from those without. The best cut-off was 0.155 μg/L with sensitivity, specificity, positive and negative predictive values as well as accuracy of 100%, 99.7%, 91.7%, 100% and 99.7%, respectively. Positive and negative likelihood ratios were 329 and zero, respectively.

CONCLUSIONS

Measurement of PCT is a sensitive and accurate method for detecting MTC in patients with thyroid nodules and can thus be a reliable alternative to CT measurement.

Procalcitonin as Marker of Recurrent Medullary Thyroid Carcinoma: A Systematic Review and Meta-Analysis

BACKGROUND

Calcitonin measurement is pivotal in the management of medullary thyroid carcinoma (MTC), but several pitfalls can affect its reliability. Other potential markers have been proposed, and procalcitonin (ProCT) has been reported as promising. The present study was undertaken to summarize the published data and provide more robust estimates on the reliability of ProCT as marker in the management of patients with MTC.

METHODS

The systematic review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The sources comprised studies published through May 2018. Journal Articles that reported series of MTC patients undergone ProCT during postoperative follow-up were searched. A random-effects model was used for statistical pooling of the data. The I² index was used to quantify the consistency among the studies. The Egger test evaluated the possible presence of significant publication bias. Quality assessment of the studies was performed according to Quality Assessment of Diagnostic Accuracy Studies 2 (QUADAS-2).

RESULTS

According to inclusion and exclusion criteria five papers, reporting 296 MTC patients undergone ProCT evaluation, were finally selected. The number of MTC with recurrence was 140. The pooled sensitivity of ProCT in detecting recurrence was 96% (95% confidence interval [CI], 92% to 99%), with neither heterogeneity (I²=0%) nor publication bias (Egger test, 3.16; P=0.99). The pooled specificity was 96% (95% CI, 87% to 100%) with mild heterogeneity (I²=66.6%), while Egger test was not calculable.

CONCLUSION

The present meta-analysis provides evidence that ProCT is reliable to manage MTC patients during their postoperative follow-up.

Procalcitonin as a postoperative marker in the follow-up of patients affected by medullary thyroid carcinoma

AIM

Due to the limits of calcitonin, other markers are warranted to better manage medullary thyroid carcinoma patients, and procalcitonin has been reported as promising. Here we aimed to evaluate procalcitonin as a marker of medullary thyroid carcinoma in the post-treatment follow-up.

METHODS

Medullary thyroid carcinoma patients previously treated by thyroidectomy were enrolled. After complete imaging work-up (i.e. ultrasonography, computed tomography, magnetic resonance and ¹⁸FDG-PET-CT) we identified patients with structural recurrent/persistent medullary thyroid carcinoma (active medullary thyroid carcinoma) and subjects with no evidence of disease. Then, both calcitonin and procalcitonin were measured and their performance analyzed.

RESULTS

The final series included 55 medullary thyroid carcinoma patients treated and followed-up for about five years. Of these, 43 were assessed as no evidence of disease, and 12 as active medullary thyroid carcinoma. The median value of procalcitonin was significantly higher ( P < 0.0001) in active medullary thyroid carcinoma patients (3.10 ng/mL) than in those with no evidence of disease (0.10 ng/mL). Also, calcitonin levels of active medullary thyroid carcinoma (96.7 pg/mL) were significantly ( P < 0.0001) higher than that of no evidence of disease (2.0 pg/mL). At the receiver operating characteristic curve analysis, the optimal cut-off of procalcitonin was ≥0.32 ng/mL with 92% sensitivity and 98% specificity, while the most accurate threshold of calcitonin was ≥12.0 pg/mL with 100% sensitivity and 91% specificity. There was no active medullary thyroid carcinoma with simultaneously negative results of procalcitonin and calcitonin.

CONCLUSIONS

Procalcitonin is reliable in discriminating medullary thyroid carcinoma patients with active disease from those with no evidence of disease. We suggest using procalcitonin as complementary to calcitonin to follow-up medullary thyroid carcinoma patients.

Clinical challenges with calcitonin-negative medullary thyroid carcinoma

PURPOSE

Medullary thyroid carcinoma (MTC) is a relatively uncommon malignant tumor of the parafollicular C cells of the thyroid, which distinguishing feature is the production of calcitonin (CT). CT is a well-recognized tool in the diagnosis and the postsurgical follow-up of patients with MTC with a high sensitivity and specificity, and represents a powerful prognostic indicator. Usually, there is a direct correlation between tumor size and basal CT levels. However, few cases of CT-negative MTCs have been reported in literature and criteria for diagnosis and follow-up are still controversial.

METHODS

We performed a brief review on CT-negative MTC and reported our experience on this rare condition, focusing on the clinical characteristics at presentation, the histological and immunostaining features, and the management.

RESULTS

Fifteen cases of large, palpable, CT-negative MTCs have been reported in the literature so far; moreover, we reported four cases followed at our center.

CONCLUSIONS

Although CT-negative MTC is rare, normal/low serum levels of CT and CEA cannot completely exclude the possibility of the diagnosis, when suspected. It is well accepted that early diagnosis is crucial, but there is still no consensus on the optimal postoperative surveillance strategy. The ultrasound evaluation of the cervical region, together with abdominal computerized tomography scan, chest X-ray, and fluorine18-fluorodeoxyglucose ((18)F-FDG) PET/computed tomography (FDG-PET/CT), would be recommended in the follow-up of such cases.

Pediatric Medullary Thyroid Carcinoma

Medullary thyroid carcinoma (MTC), which originates from thyroid parafollicular C cells, accounts for 3 to 5% of thyroid malignancies. MTC occurs either sporadically or in an inherited autosomal dominant manner. Hereditary MTC occurs as a familial MTC or as a part of multiple endocrine neoplasia (MEN) type 2A and B syndromes. A strong genotype-phenotype correlation has been observed between hereditary MTC and germ-line "gain of function" mutations of the RET proto-oncogene. Most cases of pediatric MTC are hereditary whereas sporadic MTC is rare in children and is usually diagnosed in adults. Therefore, MTC in children is most often diagnosed in the course of a familial genetic investigation. The standard treatment of MTC mainly requires surgery involving total thyroidectomy and central neck node dissection before extrathyroidal extension occurs. To prevent MTC development in hereditary syndromes, prophylactic thyroidectomy is performed in presymptomatic patients. An appropriate age at which the surgery should take place is determined based upon the data from genotyping, serum calcitonin measurements, and ultrasonography. For the treatment of advanced MTC cases, the broad spectrum receptor tyrosine kinase inhibitors vandetanib and cabozantinib, which also inhibit RET, are used although they are not always effective.

Use of fine-needle aspirate calcitonin to detect medullary thyroid carcinoma: A systematic review

BACKGROUND

The measurement of calcitonin in washout fluids of thyroid nodule aspirate (FNA-calcitonin) has been reported as accurate to detect medullary thyroid carcinoma (MTC). The results from these studies have been promising and the most updated version of ATA guidelines quoted for the first time that "FNA findings that are inconclusive or suggestive of MTC should have calcitonin measured in the FNA washout fluid." Here we aimed to systematically review published data on this topic to provide more robust estimates.

RESEARCH DESIGN AND METHODS

A comprehensive computer literature search of the medical databases was conducted by searching for the terms "calcitonin" AND "washout." The search was updated until April 2015.

RESULTS

Twelve relevant studies, published between 2007 and 2014, were found. Overall, 413 thyroid nodules or neck lymph nodes underwent FNA-calcitonin, 95 were MTC lesions and 93 (97.9%) of these were correctly detected by this measurement regardless of their cytologic report.

CONCLUSIONS

The present study shows that the above ATA recommendation is well supported. Almost all MTC lesions are correctly detected by FNA-calcitonin and this technique should be used to avoid false negative or inconclusive results from cytology. The routine determination of serum calcitonin in patients undergoing FNA should improve the selection of patients at risk for MTC, guiding the use of FNA-calcitonin in the same FNA sample and providing useful information to the cytopathologist for the morphological assessment and the application of tailored ancillary tests.