Cases Of Medullary Thyroid Carcinoma Research Articles

ODP450 A Case of Metastatic Medullary Thyroid Cancer Presenting with Pathologic Hip Fracture

Abstract Introduction Medullary thyroid cancer accounts for less than 5% of thyroid malignancies. Distant metastatic disease typically presents in lymph nodes, lung, liver and bone. We present a patient who initially presented with a pathologic hip fracture with bone biopsy revealing medullary thyroid carcinoma. Case Description A 44-year-old male with no past medical history presented to the emergency department for right hip pain following a mechanical fall. Imaging showed a right femoral neck pathologic fracture as well as lytic lesions within the right femoral neck and right ilium. Family history was significant for pancreatic cancer and breast cancer. The patient underwent bone biopsy of the right femur followed by total hip arthroplasty. Bone biopsy revealed metastatic medullary thyroid carcinoma. Thyroid ultrasound showed a 1.2 centimeter right solid hypoechoic nodule along with extensive cervical lymphadenopathy. Further imaging revealed metastatic disease throughout the thoracic spine, mediastinal lymphadenopathy, and a left 2.2 centimeter adrenal lesion with peripheral enhancement and possible necrosis. Carcinoembryonic antigen (CEA) level was 551 ng/mL (normal <4.7), calcitonin was 2,498 pg/mL (normal <10), and calcium levels were normal. Plasma free metanephrines were normal and plasma normetanephrines were less than two times the upper limit of normal. Genetic testing on the bone biopsy specimen revealed a RET p. C618S variant. Germline RET testing was collected. The patient was discharged with close follow-up with oncology to initiate systemic therapy and follow-up with endocrinology for the adrenal mass. Discussion Majority of cases of medullary thyroid carcinoma are sporadic. Patients typically present with a thyroid nodule with many having cervical lymph node involvement at diagnosis and 5-10% having distant metastatic disease. Our patient's initial presentation was unique in that he presented with a pathologic fracture. Bone metastases can be seen in about 30% of cases of metastatic medullary thyroid carcinoma. Calcitonin levels greater than 500 pg/mL require additional imaging to exclude metastatic disease. If RET mutational status is unknown, patients should be screened for primary hyperparathyroidism and pheochromocytoma. Screening for pheochromocytoma is critical in preoperative management of these patients. Treatment for patients with metastatic disease involves surgery, external beam radiotherapy, and kinase inhibitors. Presentation: No date and time listed

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.

Rapid and long-lasting response to selpercatinib of paraneoplastic Cushing’s syndrome in medullary thyroid carcinoma

The endocrine secretions of carcinomas can be life-threatening. Medullary thyroid carcinoma (MTC) is a rare cancer that is often associated with cortisol secretion, leading to paraneoplastic Cushing’s syndrome. Mutations of the proto-oncogene RET are driver molecular events in 70% of MTC cases. Here, we report a case of a woman, born in 1956, who was diagnosed with sporadic MTC in 2005, with subsequent relapses treated with focal treatments. In April 2019, she presented with severe and rapidly progressive paraneoplastic Cushing’s syndrome associated with lymph node, lung, liver and bone metastases. A supraclavicular lymph node biopsy revealed a somatic p.M918T (c.2753T>C) mutation in exon 16 of the RET proto-oncogene. The patient began treatment with selpercatinib in September 2019. Clinical efficacy was immediate. Chronic diarrhea disappeared within a few days. Clinical hypercorticism quickly disappeared, with quick improvements in muscle and skin conditions and fatigue. Two months after treatment initiation, urinary free cortisol normalized to 42 µg/24 h. Levels of the tumor markers carcinoembryonic antigen (CEA) and calcitonin also greatly decreased from baseline. After 34 months of treatment, selpercatinib elicits sustained clinical, biological and morphological responses. In summary, this case report illustrates the rapid and long-lasting antisecretory effect of selpercatinib associated with tumor control. As Cushing’s syndrome associated with medullary thyroid cancer is associated with poor prognosis, this case report is very encouraging. In addition, this suggests the potential benefit of molecular testing in all cases of medullary thyroid cancer.

Medullary thyroid carcinoma diagnosed with liquid-based cytology and immunocytochemistry

ABSTRACT Medullary thyroid carcinoma (MTC) is a rare neuroendocrine malignancy that arises from the parafollicular cells (C cells) secreting calcitonin. This study summarizes our experience in the diagnosis of MTC with ultrasound-guided thyroid FNA, subsequently processed with liquid-based cytology (LBC) and immunocytochemistry (ICC). We searched our laboratory archives for thyroid FNA cases with an interpretation of positive or suspicious for MTC, during the period 2004–2018. A total of 20 cases (18 thyroid FNAs; two lymph node FNAs) were selected and included in this study. These displayed high cellularity and a discohesive pattern, with a few loose syncytial groups. There was some variation in the cell size and shape both across and within our cases. Most MTCs (n = 15) exhibited a predominant plasmacytoid/epithelioid cell morphology, whereas five of our cases showed a spindle cell pattern. Of interest, none of eight MTC microcarcinomas (≤1 cm) showed a spindle cell morphology. Amyloid was found in 11/20 cases (55%), while binucleation/multinucleation in 17/20 (85%), and nuclear pseudoinclusions in 3/20 MTC cases (15%). Nuclei exhibited a granular, “salt and pepper” chromatin in all cases. ICC was performed in 18/20 cases (90%). Calcitonin, CEA, TTF1, and Chromogranin were positive wherever applied, whereas thyroglobulin and CK19 were negative. In conclusion, ultrasound-guided thyroid FNA – processed with LBC and ICC – is a reliable modality to detect MTC preoperatively, facilitating the management of such patients.

Amphicrine Medullary Thyroid Carcinoma - a Case-Based Review Expanding on Its MUC Expression Profile.

Amphicrine phenotype in medullary thyroid carcinoma (MTC) is a rare phenomenon characterized by tumor cells that show both endocrine differentiation (calcitonin secretion) and exocrine differentiation (mucin production and secretion). Not much is known about the pathobiology of amphicrine MTCs. This report undertook a case-based review approach by discussing the cytological, histopathological, and ultrastructural features of this rare enigmatic entity, expanding on the radiological and novel MUC immunohistochemistry findings from a 28-year-old MEN2B syndrome patient with C cell hyperplasia and multifocal MTC with amphicrine features. The patient had widespread hematogenous metastases at presentation. MUC immunoexpression analysis revealed evidence of micro-lumina formation, and unique to-date unreported expression patterns of MUC1, MUC5AC, and MUC6 in an amphicrine subtype of MTC. Review of the literature identified five other MTC cases with well-documented amphicrine features. Of these six cases, two were associated with MEN2B syndrome, and four had metastatic disease. Follow-up was available in three patients, and two died of disease. Recognition of this rare subtype of MTC may be of clinical interest given their frequent link to MEN2B syndrome and biological aggressiveness.

UNUSUAL PRESENTATION OF A THYROID MALIGNANCY: A CASE REPORT

Medullary thyroid carcinoma is a rare malignancy. We report a case of Medullary thyroid carcinoma in a 56-year-old male patient. Patient presented with lower limb paresis and severe hypokalemia. Cushing’s syndrome is a rare complication of Medullary thyroid carcinoma [MTC] and is due to ectopic Adrenocorticotropic [ACTH] secretion by tumor cells. Cushing’s syndrome presents a challenging diagnostic and management issue in patients with MTC. Entire clinical history, laboratory investigations, microscopic pictures are discussed in detail.

A Case of Medullary Thyroid Carcinoma Combined with Papillary Microcarcinoma and Literature Review

A Case of Medullary Thyroid Carcinoma Combined with Papillary Microcarcinoma and Literature Review

Medullary Thyroid Cancer: Case Series Presentation

Background: Medullary thyroid carcinoma (MTC) is a rare neuro-endocrine tumor arising from the C-cells of the thyroid. About 20- 25 % of MTC cases may be associated with hereditary syndromes like MEN 2A, MEN 2B and Familial MTC.

Application of serum markers in medullary thyroid carcinoma

Objective: To discuss the diagnostic value of calcitonin(CT), carcinoembryonic antigen (CEA), neuron-specific enolase (NSE), pro-gastrin releasing peptide (Pro-GRP) and chromogranin A (CgA) in the identification of medullary thyroid carcinoma (MTC). Methods: The CT levels in 105 cases of MTC, 50 cases of papillary thyroid carcinoma, 10 cases of thyroid follicular carcinoma, 5 cases of undifferentiated thyroid carcinoma, 50 cases of benign thyroid diseases, 30 cases of non-thyroid malignant tumors and 50 cases of healthy controls were measured from February 2017 to August 2019 at the Department of Clinical Laboratory, Cancer Hospital affliated to Fudan University. Additionally, 79 cases of MTC, 30 cases of non-MTC thyroid malignant tumors and 30 healthy controls were selected for the measurement of CEA, NSE, Pro-GRP and CgA levels. The receiver operating curve was utilized to clarify the area under the curve (AUC), sensitivity, and specificity of each indicator to distinguish between different groups. Results: The medians of CT concentrations in the group of MTC patients was 607.2 (152.5,2 777.5)pg/ml, which was statistically significantly higher than that of the subjects in the group of papillary thyroid carcinoma 1.48 (0.5,2.91)pg/ml, follicular thyroid carcinoma 1.90 (0.82,2.99)pg/ml, undifferentiated thyroid carcinoma 0.50 (0.50,4.93)pg/ml, benign thyroid disease 1.30 (0.50,2.79)pg/ml, non-thyroid malignancies 1.36 (0.50,2.89)pg/ml and healthy controls 2.05 (0.89,3.18)pg/ml. The sensitivity, specificity and AUC of CT to distinguish MTC vs. non-MTC patients was 96.2%, 99.3% and 0.99, respectively. The maximum diameter (>1 cm, P=0.001, OR=15.74) and number (>1, P=0.04, OR=3.4) of nodules were two independent risk factors for elevated CT. CEA (AUC=0.94), NSE (AUC=0.65), Pro-GRP (AUC=0.94) and CgA (AUC=0.83) could all distinguish MTC vs. non-MTC thyroid malignancies. The AUC, sensitivity and specificity by combining CT, CEA, NSE, Pro-GRP and CgA to differentiate MTC vs. non-MTC thyroid malignancies was 1, 100% and 100%, respectively. Conclusions: CT, CEA, NSE, Pro-GRP and CgA may be helpful for the auxiliary diagnosis of MTC. The combination of these indicators in the diagnosis of MTC has high sensitivity and specificity.

Cytomorphological analysis of histologically confirmed cases of medullary thyroid carcinoma

Abstract Medullary thyroid carcinoma (MTC) is a rare neuroendocrine malignant tumor of parafollicular C-cell origin of the thyroid gland, whose tumor cells typically produce calcitonin. The serum level of calcitonin produced by tumor cells is a sensitive tumor marker. An elevated serum level of this and the simultaneous presence of a thyroid nodule confirmed by ultrasound raise a reasonable suspicion of MTC. Still, the first-line MTC confirmation method in diagnosing MTC is fine-needle aspiration cytology (FNA). Objective: The aim of our study was the clinicopathological and cytomorphological analysis of histologically confirmed MTC cases obtained with FNA, as well as their comparison with the clinicopathological and cytomorphological characteristics of papillary thyroid carcinoma (PTC). Material and method: In our retrospective study, we analyzed the FNA cytology findings of patients with nodular goiter examined between 2013-2019 and the available clinical data. Results: In the 7-year period, 1,808 fine-needle aspiration examinations were performed, of which we identified 12 MTC and 77 PTC cases. The average age of patients diagnosed with MTC was 53±13 years. There were nine women and three men in examined cases. The average diameter of the nodules was 14±5 mm. All of our cases were of the sporadic type. The average age of patients diagnosed with MTC was greater than that of patients diagnosed with PTC (53 vs. 44 years, p=0.02367). A female predominance is observed in both diseases, although this is more pronounced in PTC. The diameter of the MTC nodules does not differ significantly from the mean size of the PTC nodules (14 vs. 17 mm, p=0.3138). The cytomorphological characteristics of the MTC cases we examined correspond to those described in the international literature, with minor differences. Conclusions: MTC is one of the rarer thyroid cancers, which is often difficult to distinguish from other types of thyroid cancer based on clinical features alone. Average age at diagnosis is greater than patients with PTC. Accurate diagnosis is critical as it requires a different approach than other types of thyroid cancer, it may require a different surgical approach, and may benefit from targeted therapy. Therefore, knowledge of the cytomorphology of MTC is essential for accurate diagnosis and optimal patient care.

Four cases of medullary thyroid carcinomas associated with multiple endocrine neoplasia 2B with rearranged during transfection codon M918T mutation in the same family.

Multiple endocrine neoplasia (MEN) with medullary thyroid carcinoma (MTC) is associated with rearranged during transfection (RET) mutations. The authors encountered four cases of MTC-related MEN type 2B (MEN2B) with RET codon M918T mutation in one family. Case 1 included a 19 year-old male diagnosed with MTC with lung metastases. Genetic testing revealed an RET codon M918T mutation, which indicated MEN2B. The patient responded partially to vandetanib and the disease has shown no progression in 25 months. Case 2 involved the mother of the patient in Case 1. She underwent total thyroidectomy (TT) when diagnosed with MTC-related MEN2B at 12 years of age, but was not counseled adequately. Cases 3 and 4 involved the sisters of the Case 1 patient and were assessed after Case 1 was diagnosed. Genetic testing revealed the same mutation. Case 3 was diagnosed with MTC and underwent TT. Case 4 was asymptomatic but underwent prophylactic TT; histopathologic examination revealed MTC tissue. Prophylactic TT prevented MTC from being detected at an advanced state. Genetic counseling is essential in treating MEN2B. The mother was uninformed about the genetic characteristics of MEN2B, delaying the detection of MTC in her children. The present study reaffirms the importance of family history and screening.

Performing Calcitonin Immunocytochemistry on an Additional ThinPrep Slide in Fine-Needle Aspiration Diagnosis of Medullary Thyroid Carcinoma

This study reviewed the institutional experience of performing calcitonin immunostain on an additional ThinPrep slide in fine-needle aspiration (FNA) diagnosis of medullary thyroid carcinoma (MTC). Thyroid FNA cases with MTC suspected or included in the differential diagnosis during cytologic evaluation and calcitonin immunostain performed were retrieved and reviewed. Calcitonin immunostain was performed in 132 cases with 41 positive, 81 negative, and 10 indeterminate results. All calcitonin-positive cases had a cytologic diagnosis of MTC while all calcitonin-negative cases were cytologically classified as non-MTCs except for two cases suspicious for MTC. In 10 cases with an indeterminate calcitonin result, diagnoses of non-MTC and suspicious for MTC were rendered in 6 and 4 cases, respectively. Histopathologic follow-up was available in 85 (64%) cases. All cytologically diagnosed MTC cases were confirmed on histopathology. In 3 MTC cases with an indeterminate calcitonin result, 1 case was misclassified cytologically as follicular neoplasm. The calculated sensitivity, specificity, positive predictive value, and negative predictive value of calcitonin immunostain were all 100% for diagnosing MTC. Our study demonstrates the feasibility of performing calcitonin immunostain on an additional ThinPrep slide. Calcitonin immunocytochemistry is a valuable adjunct test for FNA diagnosis and differential diagnosis of MTC.

Medullary Thyroid Cancer: Case Series Reports and Literature Review

Background: Medullary thyroid carcinoma (MTC) is a rare neuro-endocrine tumor that arises from the C-cells of the thyroid. About 20- 25 % of MTC cases may be associated with hereditary syndromes like MEN 2A, MEN 2B and Familial MTC. The survival rate is related mainly to the age of the patient, stage of the disease and completion of the surgical resection.&#x0D; Methods: Retrospective review of 11 patients who were diagnosed with medullary thyroid cancer in our general surgery department during the period from 2011 to 2021. All patients had preoperative assessment including history taking, clinical examination, tumor marker (calcitonin and CEA), thyroid function testing, ultrasonography and FNAC. All patients underwent genetic assessment to exclude any underlying genetic mutation.&#x0D; Results: The mean age of diagnosis was 57.73 ± 16.45 years of age. Three patients were males and eight were females. All patients had total thyroidectomy, central and lateral neck dissection except one patient who had prophylactic thyroidectomy due to familial inherited RET mutation. Two patients had recurrence; both of them had high-stage tumor (T3 and T4) with multiple cervical lymph nodes metastasis. The sensitivity of serum calcitonin for the detection of MTC was about 98%. Patients, who had localized disease and underwent complete surgical resection, had good overall survival rates compared with patients with advanced disease.&#x0D; Conclusion: MTC represent a heterogeneous group of thyroid cancers. The overall survival is better than that of undifferentiated thyroid cancers. Complete resection of the thyroid tumor and any local or regional metastases provides the only cure for patients with MTC. Further researches are still needed to improve our understanding and management of MTC.

Medullary thyroid carcinoma (MTC): unusual metastatic sites.

SummaryMedullary thyroid carcinoma (MTC) has a varying clinical course; distant metastases are frequently present even at diagnosis. We present two MTC cases with unusual metastatic sites. Two female patients are presented with slow progressive MTC. The first case developed distant metastases 23 years after diagnosis and underwent locoregional therapies. At the same time a breast mass developed representing MTC metastasis. Treatment with vandetanib led to long-term disease stabilization. The second patient is presented with metastases in the pancreas 13 years after diagnosis. Shortly, a painful mass developed in the mandible and metastasis of MTC was diagnosed. Disease progression was recorded 20 months after the initiation of local and systemic therapy. Such cases have only rarely been reported in the literature and highlight the need for prompt recognition of unexpected MTC metastases.Learning pointsUnusual sites of metastasis may appear in patients with medullary thyroid carcinoma (MTC) years after the initial diagnosis.Although rare, unexpected MTC metastases highlight the need for prompt recognition and appropriate treatment.Local recurrences accompanied by inappropriately low calcitonin levels should prompt further investigation for possible distant metastatic disease.Systemic treatment with tyrosine kinase inhibitors may be effective even in patients with unusual metastases from MTC.

Constitutive Cytomorphologic Features of Medullary Thyroid Carcinoma Using Different Staining Methods.

(1) Background: Accurate preoperative identification of medullary thyroid carcinoma (MTC) is challenging due to a spectrum of cytomorphologic features. However, there is a scarcity of studies describing the cytomorphologic features as seen on fine-needle aspiration (FNA) smears prepared using different staining methods. (2) Methods: We performed a retrospective study on MTC cases with available FNA slides from 13 hospitals distributed across 8 Asia-Pacific countries. The differences in the constitutive cytomorphologic features of MTC with each cytopreparatory method were recorded. A comparative analysis of cytologic characteristics was carried out with appropriate statistical tests. (3) Results: Of a total of 167 MTC samples retrospectively recruited, 148 (88.6%) were interpreted as MTC/suspicious for MTC (S-MTC). The staining methods used were Papanicolaou, hematoxylin-eosin, and Romanowsky stains. Seven out of the eleven cytologic criteria can be readily recognized by all three cytopreparatory methods: high cellularity, cellular pleomorphism, plasmacytoid cells, round cells, dyshesive cells, salt-and-pepper chromatin, and binucleation or multinucleation. An accurate diagnosis was achieved in 125 (84.5%) of the 148 samples whose FNAs exhibited five or more atypical features. Conclusions: The present work is the first study on MTC to compare the morphological differences among the cytologic staining techniques. We investigated the constitutive features and the reliability of diagnostic parameters. A feasible scoring system based upon cytomorphologic data alone is proposed to achieve a high degree of diagnostic accuracy.

What Lies Beneath? - Medullary Thyroid Cancer in Nodular Graves’ Disease

Abstract Background: Medullary thyroid carcinoma (MTC) accounts for 1%-2% of thyroid cancers in the United States (US). MTC originates from thyroid parafollicular C-cells, occurring either sporadically or hereditarily as part of type 2 multiple endocrine neoplasia (MEN) or familial MTC (FMTC). Hyperthyroidism is prevalent in approximately 1.2%, and Graves’ Disease (GD) is the most common cause of hyperthyroidism in the US. GD is an autoimmune disorder that results in increased thyroid hormone production due to the stimulation of TSH receptor by thyrotropin receptor antibodies (TRAb). Thyroid carcinoma in general is uncommon in GD patients, while MTC is extraordinarily rare. We report a case of sporadic MTC in GD, which is extremely rare. A recent publication stated that there were only 15 reported cases of MTC coexisting in GD until 2019. Clinical Case: A 62-year-old male with hypertension, diabetes and obesity presented to the endocrine surgery clinic with symptoms of diaphoresis, chest pain and fullness, shortness of breath, and palpitations. The patient had a brother with a pancreatic mass of unknown pathology and multiple family members with thyroid disease. On physical exam, there was a palpable non-tender left-sided nodule with no lymphadenopathy. His FT4 was 8.5 (0.76-1.46 ng/dL), TSH was &amp;lt;0.006 (0.36-3.74 μIU/dL) and thyroid-stimulating antibody was 1.25 (&amp;lt;0.10 IU/L). Ultrasound showed a multinodular goitre with a dominant nodule in the left lower pole measuring 2.3x1.9x1.5 cm. He was diagnosed with GD, treated with methimazole, and his symptoms improved. Subsequent nuclear medicine uptake scan showed diffusely increased uptake and a cold nodule in the left thyroid lobe. Repeat labs showed low TSH (&amp;lt;0.01μIU/dL) and elevated FT4, CEA, calcitonin, PTH, metanephrine, and normetanephrine (1.04 ng/dl, 5.2 (3-5 ng/ml), 796 (&amp;lt;18 pg/ml), 58.10 (18.40-88.00 pg/mL), 90 (&amp;lt; OR = 57 pg/ml) and 222 (&amp;lt; OR = 148 pg/ml), respectively). A thyroid fine-needle aspiration (FNA) was suggestive of MTC (Bethesda Category VI). Total thyroidectomy with left central lymph node dissection revealed a 2.5cm MTC confined in the left lobe with focal lymphovascular invasion. His postoperative course was uneventful, and CEA and calcitonin levels trended down (1.1 ng/ml and &amp;lt;2 pg/mL, respectively). Conclusion: The coexistence of medullary thyroid carcinoma and Graves’ Disease is rare, incidental, with five-year survival rates lower than other thyroid cancers. A delayed diagnosis of MTC would be detrimental. Patients with thyroid nodules and GD are five times more likely to be diagnosed with thyroid carcinoma. Radiation, chemotherapy and thyroidectomy are standard treatment options for MTC, with total thyroidectomy being the preferred option. It is necessary to evaluate patients with GD for possible thyroid cancers, especially in the presence of nodules.

Biochemical and Genomic Changes of a Devastating Metastatic Medullary Thyroid Cancer

Abstract Introduction: Medullary thyroid carcinoma (MTC) is a neuroendocrine tumor of thyroid parafollicular C cells. About 25% of cases are hereditary, associated with MEN2 syndromes. RET M918 mutation (somatic or germline) is associated with the most aggressive form of MTC. If MTC is hereditary, further tumor genomic analysis is not routinely performed. Therefore, the somatic mutational landscape of hereditary MTCs is not frequently described in the literature. We present an unusual case of MTC with a germline M918 RET mutation, displaying an initial smoldering course followed by rapidly fatal widespread metastases. Whole exome sequencing (WES) of primary tumor and metastases revealed intertumoral heterogeneity with many somatic mutations including p53 mutation. Clinical Case: The patient with characteristic facies of MEN 2B presented with a neck mass at age 28. She had no family history of MEN. At diagnosis, calcitonin was 11,392 pg/mL and CEA was 729.7 ug/L. Pathology showed MTCs of 5 cm (right) and 2.1 cm (left) with lymph node metastases (pT3N1bMx). Genetic testing showed RET M918 mutation. Postoperative calcitonin and CEA were 3.3 pg/ml and 1.7 ug/L respectively. Tumor markers doubling time was initially about 1 year, but progressively shortened over time. Three years after surgery, calcitonin and CEA were 101 pg/ml and 387 ug/L respectively. CT chest and abdomen identified no distant metastasis. Over the next 4 months, calcitonin and CEA increased dramatically to 1821pg/ml and 3974 ug/L. The patient was admitted for acute liver failure and passed away. Autopsy revealed widely metastatic disease to liver, lungs, spleen, pituitary, right adrenal gland, bones, and brain. WES revealed 87, 283 and 591 somatic mutations in the primary tumor, lung and liver metastases respectively. The primary tumor had chromosome 1p loss whereas liver and lung metastases had somatic mutation of TP53 and single copy loss of chromosome 17 (biallelic inactivation of p53). Conclusion: This case illustrates intertumoral spatial and temporal genetic heterogeneity. Mutations detected by WES may or may not be cancer-related and their clinical relevance is often uncelar. We hypothesize TP53 biallelic loss might have contributed to the aggressive phenotype of this tumor. Also of note, even before the appearance of metastases, CEA was disproportionately higher than calcitonin, reflecting tumor dedifferentiation. Further studies are needed to address CEA threshold for additional imaging and imaging modality for early detection of metastases.

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

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

Ultrasonic Characteristics of Medullary Thyroid Carcinoma: Differential From Papillary Thyroid Carcinoma and Benign Thyroid Nodule.

The aim of this study was to evaluate the differences in ultrasonic features of patients with medullary thyroid carcinoma (MTC), papillary thyroid carcinoma (PTC), and benign thyroid nodules. This study included 53 cases of MTC, 151 cases of PTC, and 200 cases of benign thyroid nodule which were pathologically confirmed. There were no significant differences in sex and thyroid gland involvement among the MTC, PTC, and benign thyroid nodule groups. The age among the 3 groups was statistically different (P = 0.002). The TNM stage of MTC was significantly higher than that of PTC (P < 0.001). Compared with PTC, the lesion size, shape, margin, echogenicity, internal nodule component, and blood flow were significantly different in MTC (P < 0.001, P < 0.001, P < 0.001, P < 0.001, P = 0.045, P < 0.001). However, there were no differences in the form of calcification and cervical lymph node involvement between the 2 groups (P = 0.671, P = 0.128). Except for the lesion size and shape (P = 0.068, P = 0.444), MTC group have significant differences in the grade of Thyroid Imaging Reporting and Data System, lesion margin, echogenicity, internal nodule component, calcification, cervical lymph node, and blood flow compared with benign thyroid nodule group (P < 0.001, P = 0.014, P = 0.032, P < 0.001, P < 0.001, P < 0.001). Our data indicate that ultrasound have important value in preoperative diagnosis of MTC. The ultrasonic features of MTC include relatively large nodules, aspect ratio less than 1, smooth edge, solid hypoechoic, microcalcification, and rich blood flow. It is necessary to combine multiple ultrasonic features for the differential diagnosis of MTC, PTC, and benign thyroid nodules.

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.