C-cell Hyperplasia Research Articles

6454 Identifying Gaps in Obtaining Germline RET Testing for Patients with Medullary Thyroid Cancer

Abstract Disclosure: A.N. Lim: None. J. Comeaux: None. C. Ricker: None. K.S. Wei: None. T.E. Angell: None. Background: Medullary thyroid carcinoma (MTC) occurs sporadically or from germline pathogenic variants of the RET proto-oncogene in multiple endocrine neoplasia type 2 (MEN2). Current ATA guidelines recommend germline RET testing in all patients with C-cell hyperplasia or MTC. Because disparities may exist in the implementation of this recommendation, we analyzed records of patients with MTC to identify variables associated with germline RET testing. Methods: Patients with MTC were identified from a cohort study of all adult patients undergoing thyroid surgery from 2015-2022 at two affiliated academic centers: a private hospital or a safety-net hospital. Patients were categorized as RET-tested or not RET-tested. Data collection included: patient age, gender, ethnicity, nodule and lymph nodule findings on ultrasound (US), calcitonin and CEA levels, and surgical pathology results. Medical reports were reviewed for reasons that RET testing was or was not obtained. Results: Of 24 MTC patients, 50% were female, mean age ± SD was 50.8 ± 12.3, and 15 (62.5%) had Hispanic ethnicity. RET testing was performed in 14 (58.3%) patients and 3 (21.4%) had a pathogenic variant. RET-tested patients had a median nodule size of 3.45 cm (IQR 2.40-4.53) vs. 2.40 cm (IQR 0.98-3.25) in not-RET tested patients (p<0.05). There were no significant differences between groups in age, gender, ethnicity, preoperative US findings, preoperative calcitonin or CEA levels, or histopathologic status. RET testing was performed in 11/14 (78.6%) patients at the private hospital vs. only 5/10 (50.0%) patients at the safety-net hospital (p=0.20). Considering this, we further investigated the use of RET testing in the initial management of MTC patients. RET testing was performed or planned during initial management in 13/14 (92.9%) patients at the private hospital vs. only 5/10 (50%) patients at the safety-net hospital (p=0.05). At the private hospital, RET testing was requested for apparent sporadic disease (n=11), family history of MTC (n=1), and coexistent pheochromocytoma (n=1). At the safety-net hospital, RET testing was requested for apparent sporadic disease (n=4) and family history of MTC (n=1), but reportedly was not pursued in 5 patients because MTC appeared to be sporadic. Discussion: In this cohort of patients with MTC, larger nodule size was significantly associated with the rate of germline RET testing. Larger MTC tumor size alone may have prompted greater attention to germline testing, but also may have been associated with other findings, which could be further assessed with a larger sample size by multivariable analysis. The disparity in RET testing as part of initial management at the safety-net hospital may be multifactorial, but future analyses should explore provider decision-making, as well as facility and patient variables. Presentation: 6/1/2024

C-Cells hyperplasia, what is their role in the development of sporadic medullary cancer?

C-Cells hyperplasia, what is their role in the development of sporadic medullary cancer?

Suppressed thyroid stimulating hormone levels after initiation of a subcutaneous glucagon-like peptide-1 receptor agonist in a post-thyroidectomy patient managed with levothyroxine case report

ObjectivesGlucagon-like peptide-1 receptor agonist (GLP-1 RA) therapy has demonstrated an increased risk of thyroid C-cell hyperplasia and C-cell tumors in rodents. Due to this risk, a boxed warning for this drug class exists for people with a personal or family history of medullary thyroid carcinoma or multiple endocrine neoplasia syndrome type 2. There is a lack of data regarding any possible effect of GLP-1 RA therapy on serum thyroid levels. The objective of this case report is to describe a case of suppressed thyroid stimulating hormone levels after initiation of a subcutaneous semaglutide in a post-total thyroidectomy patient managed with levothyroxine in order to highlight the need for closer monitoring of these patients and further research in this area. Case SummaryThe patient described in the case underwent a total thyroidectomy in 2015 with stable thyroid hormone replacement requirements with levothyroxine for 5 years until the initiation and titration of subcutaneous semaglutide. The reduction in thyroid stimulating hormone (TSH) after starting GLP-1 RA therapy necessitated a 25 percent dose reduction of levothyroxine from her original dose. Practice implicationsThis patient experienced suppressed TSH levels following initiation and titration of subcutaneous semaglutide. The etiology of these changes may be related to the direct effects of GLP-1 RA therapy on TSH levels, changes in absorption related to delayed gastric emptying rates, secondary to GLP-1 RA-associated weight loss, or a combination of these proposed mechanisms. It may be prudent to exercise more frequent monitoring of medications that require weight-based dosing and those with a narrow therapeutic index when initiating and titrating GLP-1 RA-based therapies and is an area of potential study.

High Prevalence of Hypercalcitoninemia in a Large Cohort of Adult and Pediatric Patients With PTH Resistance Syndromes

Abstract Context Pseudohypoparathyroidism (PHP) refers to a group of rare hereditary disorders associated with resistance to parathyroid hormone (PTH) and other hormones now termed inactivating PTH/PTHrP disorders (iPPSD). Hypercalcitoninemia has been seldom reported in small series. Objective Our aim was to investigate the characteristics of hypercalcitoninemia in pediatric and adult patients with PHP/iPPSD. Methods We retrospectively collected data from 2 cohorts from 2 European endocrinology tertiary centers: the pediatric cohort comprised 88 children with available calcitonin (CT) measurements; the adult cohort included 43 individuals with simultaneous CT and PTH measurements. Results In the pediatric cohort, 65.9% had hypercalcitoninemia (median CT 15 ng/L); in the adult cohort 53.5% (mean CT 21.6 ng/L). There was no difference between CT in pediatric and adult population; we observed stable CT levels over a median follow-up of 134.5 months in adults. Notably, no correlations were detected between CT and PTH levels. Other etiologies of hypercalcitoninemia were excluded; adult patients underwent regular thyroid ultrasound to screen for medullary thyroid cancer (MTC). We performed 20 calcium stimulation tests in adult patients. While there was a significant difference in basal and peak CT between our patients, healthy subjects, and subjects with MTC, there was no difference with patients with C-cell hyperplasia. Conclusion This study underscores the common occurrence of hypercalcitoninemia in both pediatric and adult patients with PHP/iPPSD, in particular with subtypes iPPSD2 and iPPSD3. Furthermore, these patients show hyperresponsiveness to calcium stimulation tests falling between healthy subjects and patients with MTC. These findings contribute to the understanding of CT dynamics in the context of PHP/iPPSD.

Thyrogrit, supplemented with a sub-optimal dose of levothyroxine, restores thyroid function in rat model of propylthiouracil-induced hypothyroidism

BackgroundHypothyroidism is a common endocrine ailment, whose current standard of care is hormonal replacement therapy with levothyroxine (LT4). There is a medical need for alternative and safer therapies as LT4 is associated with special treatment considerations and adverse effects. Thyrogrit (THY) is a polyherbal formulation indicated for the treatment of hypothyroidism. The present study, describes the characterization of the phytocompounds present in THY and its in-vivo efficacy in rat model of hypothyroidism, in combination with a sub-optimal dose of LT4.MethodsUltra High Performance Liquid chromatography was employed for the identification of the phytocompounds present in THY. For the evaluation of its in-vivo efficacy, female Wistar rats were administered THY orally, 15-days prior to disease induction, and continued throughout the experiment. Subsequently, hypothyroidism was induced by oral administration of propylthiouracil (PTU). From day 45 onwards, animals were administered orally with a sub-optimal dose of LT4 (2 μg/kg) till the end of the study. On day 79, animals were euthanized, blood was collected for measurement of thyroid hormones and other clinical chemistry parameters. Weights of liver, kidney and thyroid were recorded. Finally, the thyroid was subjected to histopathological evaluation through hematoxylin and eosin (H&E staining), immunohistochemistry as well as immunofluorescence.ResultsThe principal phyto-components detected in THY by Ultra High Performance Liquid Chromatography included gallic acid, protocatechuic acid, corilagin, ellagic acid, piperine, guggulsterone E and Z, which are documented to exerted beneficial effects on thyroid function. In the in-vivo study, THY when supplemented with a low dose of levothyroxine restored the PTU-induced reduction in the serum levels of T3 and T4 and improved PTU-induced renal impairment. THY treatment ameliorated the hallmark histopathological changes associated with hypothyroidism and C-cell hyperplasia. Further, co-administration of THY and LT4 did not show any major non-clinical safety concerns even after the administration for more than twelve weeks.ConclusionThis study has demonstrated that co-administration of THY and LT4 improves the PTU-evoked alterations in the thyroid ultrastructure and function, abrogates hypothyroidism-associated renal impairment and exhibits an acceptable basic safety profile.Graphical abstract

Specific effects on the thyroid relevant for performing a dietary cumulative risk assessment of pesticide residues: 2024 update.

EFSA updated its previous work on the establishment of specific effects that are considered relevant for grouping pesticide residues targeting the thyroid and for performing the retrospective assessment of dietary cumulative risk (CRA). The two specific effects already selected in 2019 leading to the two cumulative assessment groups (CAGs) 'hypothyroidism' and 'C-cell hypertrophy, hyperplasia and neoplasia' were reconfirmed. Compared to 2019, the list of indicators that can be used to identify these specific effects was refined to only include histopathological changes. In a second phase of the work, data will be extracted on indicators of the specific effects from the dossiers on active substances (a.s.) used as plant protection products. The criteria for including a.s. into CAGs were also updated, together with the hazard characterisation methodology and the lines of evidence for assessing CAG-membership probabilities. The tasks related to the data extraction and the establishment of the CAGs on hypothyroidism and on C-cell hypertrophy, hyperplasia and neoplasia are beyond the scope of this report. This part of the CRA process has been outsourced and will be the subject of a separate report.

Diffuse C-Cells Hyperplasia Is the Source of False Positive Calcitonin Measurement in FNA Washout Fluids of Thyroid Nodules: A Rational Clinical Approach to Avoiding Unnecessary Surgery.

The FNA-CT is useful for the diagnosis of MTC. The aim of this study was to evaluate the performance of FNA-CT in TNs coexisting with CCH. This study retrospectively reviewed the records of 11 patients with TNs submitted to thyroidectomy on the basis of elevated basal and/or stimulated serum CT values, which at histology were not confirmed to be MTC. The results obtained in this group were compared with those of a previously reported group of histologically proven MTC patients submitted to an identical presurgical evaluation. All patients, negative for known mutations in the RET proto-oncogene, were preoperatively submitted to neck ultrasound, FNA-cytology, and FNA-CT. Approximately 6 of 11 patients showed increased (>36 ng/mL, as established in previous studies not involving patients with CCH) FNA-CT. All these patients showed diffuse CCH at histology in the thyroid lobe submitted to FNA; 5 of them were benign at histology, while only one was malignant (papillary thyroid carcinoma, PTC). The remaining 5 of 11 patients had low FNA-CT (<36 ng/mL), and all of them showed only focal CCH in the lobe submitted to FNA; three of them were malignant (2 PTC, 1 follicular carcinoma), while two were benign. Employing the currently proposed cut-off values, false-positive FNA-CT results may be observed in benign/malignant TNs with coexisting diffuse CCH. FNA-CT must therefore be cautiously used in the diagnostic approach for patients with TNs and a slightly increased basal or stimulated serum CT concentration in order to avoid unnecessary surgery.

C-Cell Hyperplasia and Cystic Papillary Thyroid Carcinoma in a Patient with Type 1B Pseudohypoparathyroidism and Hypercalcitoninaemia: Case Report and Review of the Literature.

Hypercalcitoninaemia has been described in patients with pseudohypoparathyroidism (PHP) type 1A and 1B. Elevated calcitonin levels are thought to result from impaired Gsα receptor signaling, leading to multiple hormone resistance. Evidence on the risk of medullary thyroid carcinoma (MTC) or C-cell hyperplasia in PHP patients with hypercalcitoninaemia is lacking. A 43-year-old Caucasian man was referred to our endocrinology clinic for chronic hypocalcemia associated with elevated serum parathormone levels and a single cystic thyroid nodule. The patient did not show skeletal deformities, and screening for concomitant hormone resistances was negative, except for the presence of elevated serum calcitonin levels. The workup led to a molecular diagnosis of sporadic PHP1B. Fine needle aspiration of the thyroid nodule was not diagnostic. The calcium stimulation test yielded an abnormal calcitonin response. Given the scarcity of data on the risk of thyroid malignancy in PHP and calcium stimulation test results, total thyroidectomy was performed. Histological examination revealed cystic papillary thyroid cancer in a background of diffuse C-cell hyperplasia. To our knowledge, we are the first to describe a rare form of thyroid cancer combined with C-cell hyperplasia in a patient with PHP and hypercalcitoninaemia. In the present case, a mere receptor resistance might not fully explain the elevated calcitonin levels, suggesting that hypercalcitoninaemia should be carefully evaluated in PHP patients, especially in the case of concomitant thyroid nodules. Further studies on larger cohorts are needed to elucidate this topic.

SAT540 A Case of Simultaneous Medullary Thyroid Cancer (MTC) And Papillary Thyroid Cancer (PTC) In a Patient With Germline RET Mutation

Abstract Disclosure: N. Vaghasia: None. G. Jaiswal: None. Introduction: There are only handful of cases reported of concurrent MTC and PTC in a patient with germline RET proto-oncogene mutation. Case: A 41 year old female with no PMH presented to Endocrine clinic for evaluation of recently diagnosed RET mutation. Patient’s nephew passed away at 5 weeks of age from abnormal organogenesis of heart and brain. Genetic testing showed germline RET mutation. Subsequently her brother and his two children was tested positive for RET mutation. Patient underwent genetic testing which was positive for RET mutation. Patient was found to be heterozygous for p.V804M (c.2410G&amp;gt;A) mutation reported as moderate risk mutation in the RET gene. The result was consistent with an increased risk for RET-related cancers. No family history of MTC, pheochromocytoma or primary hyperparathyroidism was identified. Patient was asymptomatic on presentation and no previous symptoms concerning for any RET mutation related disease. Her physical examination was normal. Patient underwent testing for pheochromocytoma and hyperparathyroidism which was unremarkable. Patient’s calcitonin level was also normal. Patient had US thyroid done to evaluate for nodule and was found to have 1.62 x 0.97 x 1.50 cm mixed solid cystic, hypoechoic, irregular margins and punctate echogenic foci right sided nodule. No abnormal cervical lymph nodes. Patient underwent FNA of the suspicious nodule which was reported as benign based on Bethesda classification. Patient’s calcitonin level was undetectable &amp;lt;0.2 pg/ml (0.0-5.0). Patient underwent total thyroidectomy and on surgical pathology had three papillary microcarcinomas, classic type, 0.4 cm (right lobe), 0.3 cm (left lobe) and 0.1 cm (right lobe). Patient had medullary microcarcinoma 0.2 cm on left lobe. Background thyroid with C-cell hyperplasia. No lymphovascular invasion, no extrathyroidal extension and margins cleared. Discussion: Association of simultaneous MTC-PTC have been reported in few case reports in patient with germline RET mutation. There has been no risk factors or specific patient phenotype identified in previous cases to suggest any association between the two. One important feature in our case is the presence of highly suspicious thyroid nodule which on FNA was benign. This raise an important question on whether the co-existence of MTC and PTC in germline RET mutation decreases sensitivity of FNA. Also it is yet unknown if specific mutation like in our case p.V804M (c.2410G&amp;gt;A) is associated with higher incidence of multi-tumor pathology or not. Finally, our patient had normal calcitonin level despite having MTC which is unusual. Conclusion: Coexistence of MTC and PTC in germline RET mutation is an uncommon association and more information is required to understand common features, risk factors, phenotype and cancer aggressiveness in these patients. At this point it cannot be concluded that the association is a mere coincidence. Presentation Date: Saturday, June 17, 2023

Pediatric head and neck manifestations associated with multiple endocrine neoplasia syndromes.

Multiple endocrine neoplasia (MEN) syndromes are a group of hereditary cancer syndromes that can predispose children to endocrine neoplasms developing within the head and neck. To examine the neoplastic manifestations of MEN type 1 (MEN1) and MEN type 2 (MEN2) in the pediatric head and neck. Single-institution, retrospective review of pediatric MEN between 2005 and 2022. Fifty-three children were genetically confirmed with MEN (15 MEN1, 34 MEN2A, and 4 MEN2B), while three patients received clinical diagnoses of MEN1. The male to female ratio was essentially equal (1.15:1), and a documented family history of cancer was present in 89% (50/56). After multidisciplinary evaluation, a familial MEN diagnosis was confirmed in 91% (51/56). The mean ages of initial presentation and surgical intervention were 8.9 years (SD 5) and 9.8 years (SD 4.8), respectively. Although patients with MEN2 received surgery earlier than patients with MEN1 (8.7 vs 12.7 years), surgical patients with MEN2 in this cohort were older relative to current American Thyroid Association (ATA) guidelines primarily due to late presentation. Thyroid malignancies were identified in 36% (9/25) of thyroidectomy specimens (21 MEN2A, 4 MEN2B), with medullary thyroid carcinoma (MTC) present in five MEN2A patients and three MEN2B patients (89%), and papillary thyroid carcinoma (PTC) present in one MEN2A patient (11%). Nearly 90% (8/9) of thyroid malignancies were occult, with some occurring earlier than predicted by current guidelines (ATA-MOD and ATA-H). Central neck dissections were performed in 24% (2 MEN1, 2 MEN2A, and 4 MEN2B), with two MEN2B (50%) demonstrating cervical lymph node (LN) metastases. Additional histopathologic findings included C-cell hyperplasia in 57% (12/21) of MEN2A thyroidectomy patients. Of the eight MEN1 parathyroidectomy patients, four demonstrated parathyroid hyperplasia and four presented with parathyroid adenoma. Nearly 60% required head and neck procedures. While MEN1 guidelines were appropriate for our cohort, we identified patients with MEN2 that developed MTC earlier than expected based on current ATA guidelines, including children in categories considered lower risk. In conjunction with a multidisciplinary approach, pediatric head and neck surgeons should be aware of the potential need for earlier surgical intervention in the pediatric MEN2 population.

Calcitonin levels in autoimmune atrophic gastritis-related hypergastrinemia.

Calcitonin (Ct) is currently the most sensitive biochemical marker of C-cell disease (medullary thyroid cancer [MTC] and C-cell hyperplasia), but its specificity is relatively low. Our aim was to examine whether autoimmune atrophic gastritis (AAG) and chronic hypergastrinemia, with or without chronic autoimmune thyroiditis (AT), are conditions associated with increased Ct levels. Three groups of patients were consecutively enrolled in this multicentric study: group A consisted of patients with histologically-proven AAG (n = 13; 2 males, 11 females); group B fulfilled the criteria for group A but also had AT (n = 92; 15 males, 77 females); and group C included patients with AT and without AAG (n = 37; 6 males, 31 females). Median Ct levels did not differ between the three groups. Ct levels were undetectable in: 8/13 cases (61.5%) in group A, 70/92 (76.1%) in group B, and 27/37 (73.0%) in group C. They were detectable but ≤ 10ng/L in 4/13 (30.8%), 20/92 (21.7%) and 7/37 (18.9%) cases, respectively; and they were > 10ng/L in 1/13 (7.7%), 2/92 (2.2%) and 3/37 (8.1%) cases, respectively (P = 0.5). Only three patients had high Ct levels (> 10ng/L) and high gastrin levels and had an MTC. There was no correlation between Ct and gastrin levels (P = 0.353, r = 0.0785). High gastrin levels in patients with AAG do not explain any hypercalcitoninemia, regardless of whether patients have AT or not. This makes it mandatory to complete the diagnostic process to rule out MTC in patients with high Ct levels and AAG.

Abstract #1399269: Never Too Old for Genetics: An Unusually Late Presentation of Medullary Thyroid Cancer in MEN2A

Virtually all germline RET pathogenic variant carriers develop medullary thyroid carcinoma (MTC). If possible, thyroidectomy should be performed prophylactically, before developing MTC. We describe a patient with pheochromocytoma found to have a germline RET p.Cys634Ser pathogenic variant at age sixty years who would be categorized as high risk based on genotype classification described by the American Thyroid Association and would have warranted prophylactic thyroidectomy at a young age. A 60-year-old man with history of hypothyroidism and osteopenia was found to have an adrenal mass during evaluation for kidney stones. It measured 4.1 x 3.2 x 3.8 cm on CT scan of abdomen and pelvis. MRI with and without gadolinium revealed a 4 cm left adrenal mass with T2 enhancement. Diagnosis of pheochromocytoma was confirmed with elevated levels of plasma free metanephrine and normetanephrine. The adrenal nodule showed avid uptake on PET CT Gallium-68 DOTATATE scan. No uptake was noted on the contralateral adrenal gland or in the neck. Patient underwent left adrenalectomy. Surgical pathology confirmed pheochromocytoma. Patient also had evidence of primary hyperparathyroidism (pHPT). Germline genetic analysis revealed a RET c.1900T >A(p.Cys634Ser) pathogenic variant confirming the diagnosis of multiple endocrine neoplasia type 2A (MEN2A). Calcitonin level was noted to be mildly elevated at 27.8 pg/ml. Subsequently, patient underwent total thyroidectomy, subtotal parathyroidectomy and bilateral central neck dissection. Surgical pathology revealed multifocal MTC, diffuse C-cell hyperplasia, and a foci of papillary thyroid microcarcinoma. Immunohistochemistry for calcitonin revealed diffuse C-cell hyperplasia. Patient was doing well on postoperative follow up and calcitonin level downtrended to < 2 pg/ml. Nearly all patients with MEN2A have either C-cell hyperplasia (CCH) or MTC, approximately 50% have a pheochromocytoma and 20-30% have pHPT. Age-related penetrance of CCH and hMTC is mutation dependent. Peak incidence in index patients is in the third decade of life in MEN2A. Our patient presented in the sixth decade of life. We decided to pursue genetic testing. The DOTATE scan did not show uptake in the neck and the calcitonin was only mildly elevated. However, as there is known complete penetrance of MTC in patients with MEN2A syndrome, patient underwent total thyroidectomy with central neck dissection with results of surgical pathology confirming presence of MTC. This case highlights the importance of considering genetic syndromes even in patients who present at older ages and challenges the classic genotype-phenotype correlation of the RET p.Cys634Ser pathogenic variant and MTC.

Insights Obtained from the Nontumorous Glandular Tissue in Patients with Endocrine Tumors.

The pathology of neoplasia tends to focus on the tumor that requires characterization, grading, and staging. However, nontumorous tissue surrounding the lesion can also provide information, particularly about pathogenetic mechanisms. In endocrine tissues, this takes the form of precursor lesions that characterize several genetic predisposition syndromes. In addition, because of the unique functional aspects of endocrine neoplasia, the nontumorous tissue provides evidence of hormone excess, with hyperplasia and/or atrophy and other involutional changes allowing the pathologist to confirm both hormone function by the tumor and the effects of medical therapies. In this article, we review the various clinically relevant features that should be assessed and reported to enhance clinical management of patients with endocrine neoplasms. For example, in thyroid there may be inflammatory thyroiditis or goiter of various etiologies; there may be C-cell hyperplasia either as a preneoplastic lesion in patients with genetic predisposition to medullary thyroid carcinoma or as a reactive phenomenon. Drug-induced changes can be seen in thyroid and adrenal cortex. In neuroendocrine tissues, the nontumorous tissues may show precursor lesions such as endocrine cell hyperplasia/dysplasia; there may be related or unrelated hyperplastic or neoplastic lesions. Some tissues, such as pituitary corticotrophs and adrenal cortex, develop changes that reflect feedback suppression by hormone excess that can serve as biomarkers of tumor functionality and provide enhanced clinicopathologic correlates.

"Graded early warning system" of RET germline mutation carriers in MEN2A/MEN2B families and total thyroidectomy (report of 7 cases)

Objective: To explore the reasonable time of prophylactic thyroidectomy for RET gene carriers in multiple endocrine neoplasia(MEN) 2A/2B families. Methods: From May 2015 to August 2021, RET gene carriers in MEN2A/MEN2B families were dynamically followed up at the Department of Thyroid Head and Neck Surgery, Beijing Tongren Hospital of Capital Medical University. The high-risk patients were encouraged to undergo prophylacitc total thyroidectomy according to the principle of "graded early warning system", namely the evaluation of gene detection, calcitonin value and ultrasound examination successively. Seven cases underwent the surgery, including 3 males and 4 females, aged from 7 to 29 years. According to the risk stratification listed in the guidelines of the American Thyroid Association in 2015, there were 2 cases of the highest risk, 2 cases of the high risk and 3 cases of the modest risk. Calcitonin index remained within the normal range in 3 cases and elevated in 4 cases before operation. All 7 patients underwent thyroidectomy with lymph node dissection of the level Ⅵ performed in 4 patients. Results: The time from suggestion to operation was 2 to 37 months, with an average of 15.1 months. The 6 patients were medullary thyroid carcinoma and 1 case with C-cell hyperplasia. The follow-up time was 2 to 82 months, with an average of 38.4 months. Postoperative serum calcitonin levels of all cases decreased to normal level, with biochemical cure. There was no sign of recurrence on ultrasound examination. All 7 patients had no serious complications, no obvious thyroid dysfunction. Their height, weight and other indicators of pediatric patients were similar to those of their peers, with normal growth and development. Conclusion: For healthy people with MEN2A/MEN2B family history, prophylactic thyroidectomy can be carried out selectively based on the comprehensive evaluation of "graded early warning system" with strict screening and close monitoring.

Update on C-Cell Neuroendocrine Neoplasm: Prognostic and Predictive Histopathologic and Molecular Features of Medullary Thyroid Carcinoma.

Medullary thyroid carcinoma (MTC) is a C-cell-derived epithelial neuroendocrine neoplasm. With the exception of rare examples, most are well-differentiated epithelial neuroendocrine neoplasms (also known as neuroendocrine tumors in the taxonomy of the International Agency for Research on Cancer [IARC] of the World Health Organization [WHO]). This review provides an overview and recent evidence-based data on the molecular genetics, disease risk stratification based on clinicopathologic variables including molecular profiling and histopathologic variables, and targeted molecular therapies in patients with advanced MTC. While MTC is not the only neuroendocrine neoplasm in the thyroid gland, other neuroendocrine neoplasms in the thyroid include intrathyroidal thymic neuroendocrine neoplasms, intrathyroidal parathyroid neoplasms, and primary thyroid paragangliomas as well as metastatic neuroendocrine neoplasms. Therefore, the first responsibility of a pathologist is to distinguish MTC from other mimics using appropriate biomarkers. The second responsibility includes meticulous assessment of the status of angioinvasion (defined as tumor cells invading through a vessel wall and forming tumor-fibrin complexes, or intravascular tumor cells admixed with fibrin/thrombus), tumor necrosis, proliferative rate (mitotic count and Ki67 labeling index), and tumorgrade (low- or high-grade) along with the tumor stage and the resection margins. Given the morphologic and proliferative heterogeneity in these neoplasms, an exhaustive sampling is strongly recommended. Routine molecular testing for pathogenic germline RET variants is typically performed in all patients with a diagnosis of MTC; however, multifocal C-cell hyperplasia in association with at least a single focus of MTC and/or multifocal C-cell neoplasia are morphological harbingers of germline RET alterations. It is of interest to assess the status of pathogenic molecular alterations involving genes other than RET like theMET variants in MTC families with no pathogenic germline RET variants. Furthermore, the status of somatic RET alterations should be determined in all advanced/progressive or metastatic diseases, especially when selective RET inhibitor therapy (e.g., selpercatinib or pralsetinib) is considered. While the role of routine SSTR2/5 immunohistochemistry remains to be further clarified, evidence suggests that patients with somatostatin receptor (SSTR)-avid metastatic disease may also benefit from the option of 177Lu-DOTATATE peptide radionuclide receptor therapy. Finally, the authors of this review make a call to support the nomenclature change of MTC to C-cell neuroendocrine neoplasm to align this entity with the IARC/WHO taxonomy since MTCs represent epithelial neuroendocrine neoplasms of endoderm-derived C-cells.

Prophylactic and Early Thyroidectomy in RET Germline Mutation Carriers in Pediatric and Adult Population: Long-Term Outcomes of a Series of 63 Patients

Prophylactic and early thyroidectomy in RET germline mutation carriers allows the removal of the thyroid before medullary thyroid carcinoma (MTC) develops, or while it is still confined to the gland. This study was aimed to assess the clinicopathological features in RET carriers according to the age at surgery and the long-term outcomes after prophylactic and early thyroidectomy. A retrospective analysis of 63 operated asymptomatic RET carriers diagnosed after familial genetic screening was performed. Twenty-one RET carriers were operated at pediatric (<18 yrs) and 42 at adult (≥18 yrs) age. Serum preoperative calcitonin levels were significantly lower in pediatric compared to adult patients (p = 0.04); moreover, adult RET carriers had a greater frequency of microMTC at pathology (p = 0.009). Permanent postoperative morbidity occurred in 9.5% of patients, without differences between the two groups. Biochemical postoperative cure was achieved in all patients. At a median follow-up of 14 years, all C-cell hyperplasia patients are disease-free; conversely, biochemical, and structural recurrence of disease occurred in three adults and one pediatric patient with microMTC. The independent predictive factors of MTC were the age at surgery, the preoperative calcitonin level and the RET mutational risk profile (p < 0.02). In conclusion, prophylactic and early thyroidectomy are safe and effective procedures in achieving definitive cure in most RET carriers. However, since recurrences may occur at long-term in case of microMTC, thyroidectomy should be possibly performed earlier to prevent microMTC development.

Age-Related Changes in Calcitonin-Producing Thyroid C-Cells of Male Wistar Rats.

Thyroid C-cells secrete the hormone calcitonin (CT) which acts as an inhibitor of bone resorption. Our aim was to examine the age-related changes in the structure and function of CT-producing C-cells, using histomorphometric, ultrastructural, and biochemical analyses. We used young adult (3-months-old), middle-aged (16-months-old), and old (24-months-old) male rats. The peroxidase-antiperoxidase method was applied for localization of CT. Stereological analysis was performed using the newCAST stereological software package. Serum samples were analyzed for the determination of CT, testosterone (T), calcium (Ca2+), and phosphorus (P). We found a significant increase in the volume density (Vv) of C-cells in both older groups (p < 0.05). The percentage of smaller volume range C-cells increased (p < 0.0001), while the proportion of greater volume range C-cells decreased (p < 0.05) with ageing. Ultrastructural analysis revealed a larger number of secretory granules in older rats. Serum CT increased (p < 0.001), while serum T and P were reduced (p < 0.01) in older rats. Serum Ca2+ was lower (p < 0.0001) in middle-aged rats compared to young adults. We revealed a 20% incidence of C-cell hyperplasia in older rats and one case of medullary thyroid carcinoma in an old rat. Our findings indicate that the ageing process causes significant histomorphometric changes at the thyroid C-cell level.

Medullary thyroid cancer with RET V804M mutation: more indolent than expected?

BackgroundSignificant genotype-phenotype variability among multiple endocrine neoplasia type 2A patients with a RET V804M mutation has been reported. MethodsPatients with a RET V804M mutation treated at a single center were identified (January 1996–December 2020). The baseline characteristics, operative details, pathology, biochemical, and long-term data were analyzed. ResultsThere were 79 patients; none developed pheochromocytoma or hyperparathyroidism or died in the study period. The mean age was 41.5 years (range = 1.0–81.0 years); 46.8% were men. Of 68 surgical patients, 53 (77.9%) underwent total thyroidectomy and 15 (22.1%) underwent total thyroidectomy with central neck dissection with or without lateral neck dissection. Twenty-four patients had elevated preoperative calcitonin, of whom 12 underwent total thyroidectomy (median = 7.5; range = 5.0–237.0 pg/mL), 10 underwent total thyroidectomy + central neck dissection (median = 27.6; range = 5.1–147.0 pg/mL), and 2 underwent total thyroidectomy + central neck dissection + lateral neck dissection (median = 3182.0; range = 361.0–6003.0 pg/mL). Pathology was benign (27.9%), papillary thyroid cancer alone (1.5%), C-cell hyperplasia (23.5%), and medullary thyroid cancer (47.1%; median tumor size = 3.0 mm). Three patients had elevated calcitonin postoperatively (median follow-up time = 60.0 months). In adjusted modeling, a preoperative calcitonin >5 pg/mL was associated with having medullary thyroid cancer on final pathology (odds ratio = 13.3; 95% confidence interval, 3.2–56.3; P < .001). ConclusionIn this large United States cohort of surgical patients with a RET V804M mutation, most had indolent disease and were without classic multiple endocrine neoplasia type 2A features. Calcitonin >5 pg/mL may serve as a meaningful value to guide surveillance and timing of surgery.

Agresivni klinički tok medularnog mikrokarcinoma štitaste žlezde

Medullary thyroid carcinoma is a form of neuroendocrine tumor that arises from parafollicular C cells which produce calcitonin. In addition to calcitonin, these cells produce smaller amounts of other peptides, including carcinoembryonic antigen (CEA), which is used as a nonspecific tumor marker in the follow-up of patients with this tumor. MTC is a rare thyroid tumor and occurs three times more often in women than in men. It can occur in two forms, sporadic (80%) and familial form (20%). The familial form can occur alone or in association with other endocrine tumors within MEN 2A and MEN 2B syndromes. The sporadic form most often occurs in the fifth and sixth decades of life. The familial form is inherited autosomally dominantly, most often based on a mutation in the RET protooncogene located on chromosome 10. C-cell hyperplasia is considered to be a premalignant lesion, which precedes medullary carcinoma. Medullary carcinoma metastasizes very early. We presented a patient with a sporadic form of MTC which appeared at a typical age. Initial values of both baseline and stimulated calcitonin were not in the range for suspected MCT, but due to persistent increases in calcitonin, with elevated baseline (63 pg / mL) and higher stimulated calcitonin (96 pg / mL), the patient was referred for surgical treatment. Due to the strong correlation of calcitonin values with tumor size, the initial calcitonin values were expected to be low because the tumor was 3 mm in size. The histopathological diagnosis was C-cell hyperplasia. However, due to the fact that nodular C-cell hyperplasia is histopathologically difficult to distinguish from medullary microcarcinoma, based on the persistent increase in calcitonin levels, the patient was likely to already have metastatic disease at the time of thyroidectomy. Definitive diagnosis was made by liver biopsy. Therapy with tyrosine kinase inhibitors was introduced, and calcitonin levels strarted to decrea, but there is an increase in carcinoembryonic antigen, which is a poor prognostic parameter.

Solid Cell Nests Hyperplasia (Ultimobranchial Body Remnants) of the Thyroid: A Pitfall

Abstract Introduction/Objective Solid cell nests (SCN) are small epithelial cell nests interspersed within thyroid parenchyma, resembling squamous/transitional epithelium. SCNs, which are ultimobranchial remnants, are popularly considered pluripotent stem-cells responsible for developing follicular and C-cells. While SCNs are not an uncommon incidental findings in thyroid, solid cell nest hyperplasia is rare. SCNs are often mistaken for benign entities such as C-cell hyperplasia (CCH) or malignant lesions such as papillary thyroid carcinoma (PTC), metastatic squamous cell carcinoma, or medullary thyroid microcarcinoma (MTC). Methods/Case Report To reiterate this diagnostic dilemma, we present a case of a 57-year-old male with a six-year history of Hashimoto thyroiditis and multiple bilateral thyroid nodules. Ultrasonography revealed two nodules, one in each lobe, measuring 2.0x1.9x1.8cm(right) and 1.6x1.5x1.5cm(left). Both were solid, hypoechoic nodules with smooth margins and no echogenic foci. Fine-needle aspiration of right nodule was suspicious for follicular neoplasm, Hürthle- cell type, and the left nodule was atypia of unknown significance. Right-hemithyroidectomy specimen revealed follicular adenoma and oncocytic adenomatous nodules in a background of florid lymphocytic thyroiditis (Hashimoto). In two blocks, small solid nests of cells were identified, largest focus measuring 0.5 cm. The cells were polygonal to epithelioid with moderate amphophilic cytoplasm. Nuclei were centrally located, irregular to oval with occasional grooves. While nests had a squamoid appearance, they did not have intercellular bridges. Although nuclear grooves and evenly dispersed chromatin and chromocenters were noted, they lacked optical clearing or intra-nuclear inclusions characteristic for PTC. Thus, excluding these two possibilities, primary diagnostic considerations were SCN versus CCH. Immunohistochemical analysis showed cells positive for P63 and CK5/6 and negative for PAX-8, TTF-1, thyroglobulin, CEA, and calcitonin. Results (if a Case Study enter NA) NA Conclusion If wrongly diagnosed as CCH, patients may be placed in a high-risk category for possible development of MTC. It is, thus, necessary to be aware of SCN, which can occasionally become hyperplastic, to prevent misdiagnosis.