Thyroid Lobe Research Articles

Non‐functional metastatic thyroid carcinoma with oesophageal invasion and ulceration in a cat

AbstractAn adult, male, neutered, domestic shorthair cat was presented with a 2‐month history of dysphagia and a movable cervical mass. Cytology of the cervical mass was consistent with carcinoma. Thoracic radiographs revealed pleural effusion, cardiomegaly, diffuse patchy interstitial pattern and pulmonary nodules. Fluid analysis of the pleural effusion was consistent with marked septic neutrophilic inflammation, and Pasteurella multocida was isolated. Contrast‐enhanced cervical and thoracic computed tomography scan revealed a cervical mass in the region of the right thyroid lobe, with circumferential invasion of the oesophageal wall and well‐defined pulmonary nodules consistent with distant metastases. Oesophago‐gastroscopy was performed and revealed a proximal, oesophageal, mural mass causing severe intraluminal obstruction. Humane euthanasia was elected. Postmortem examination with histology and immunohistochemistry confirmed a thyroid carcinoma with oesophageal invasion and pulmonary metastases. The oesophageal mucosa was extensively disrupted and ulcerated by the thyroid carcinoma. Additionally, echocardiogram and postmortem examination confirmed cardiomyopathy and congestive heart failure.

Thyroid Abscess: A Very Rare Entity in Child

Abstract Thyroid abscess is a very rare clinical entity, but potentially fatal emergency in the pediatric age group, with a mortality of 3.7%–9% in acute suppurative thyroiditis (AST), it is imperative to make a timely diagnosis and start treatment accordingly, it represents 0.1% of surgical pathologies of the thyroid. The anatomical and physiological characteristics of the gland provide it with resistance to pathogens. Recurrence is still exceptional. In this case report, we discuss a rare case of thyroid abscess in a 7-year-old girl revealing a piriform sinus fistula. Through this article, we attempt to stress the need for quick and accurate diagnosis and timely intervention to prevent complications as the condition is rare and unusual. The child presented to the pediatric emergency in January 2023 for a first episode of febrile torticollis the exploration objectified a thyroid abscess treated by probabilistic antibiotic therapy with good clinical and biological evolution, 6 months later, the child consulted again for the same symptomatology with febrile torticollis, dysphagia without signs of dysthyroidism, fever, and night sweats. Cervical computed tomography showed a mass occupying the left thyroid lobe. A cervical ultrasound showed heterogeneous hypoechoic collection; poorly limited. The biological assessment objectified a hyperleukocytosis in 19090 with a predominance of neutrophils with a C-reactive protein at 150 mg/l. The management was medical including intravenous antibiotic therapy based on amoxicillin–clavulanic acid and exploration by nasofibroscopy completed by hypopharyngoscopy showed a fistula of the piriform sinus. The treatment is based on surgery by cauterization of the sinus.

A case of anterior mediastinal mature teratoma with severe inflammatory extension into the neck

BackgroundWe present the case of a rare occurrence of an anterior mediastinal mature teratoma extending into the neck, commonly referred to as a cervicothoracic mature teratoma.Case presentationA 19-year-old female presented with right-sided neck pain and swelling, which were found to be attributed to a 14 cm cystic lesion originating from the right thyroid lobe and extending into the mediastinum. A diagnosis of mediastinal teratoma with extension to the neck was made. Robot-assisted thymectomy was initiated but was complicated by dense tumor adherence to the superior vena cava and brachiocephalic veins, prompting a switch to a midline sternotomy. Simultaneous resection of the right thyroid lobe was performed due to inflammation. The transition to a midline sternotomy allowed successful excision of the tumor, which was confirmed to be a mature teratoma confined to the thoracic region. The patient's favorable postoperative course led to discharge on day 5 with no recurrence at nine months.ConclusionsEmphasizing the challenges and the importance of prompt intervention in the management of mediastinal teratomas with neck extension.

Coexisting parathyroid adenoma, thyroid carcinoma, and tuberculosis of thyroid: a case report

BackgroundCoexisting parathyroid adenoma, thyroid carcinoma, and tuberculosis of thyroid is a very rare phenomenon. Primary thyroid tuberculosis is itself very rare despite high global prevalence of tuberculosis in developing countries. Majority of thyroid tuberculosis identified in postoperative histopathology or cytopathology. The coexistence of thyroid cancer with tuberculosis or parathyroid adenoma has been reported in the literature but not a single case of the three pathologies coexisting together has been found in the literature published. We are presenting a rare case of a constellation of synchronous parathyroid adenoma, thyroid carcinoma, and thyroid tuberculosis. This case report will provoke researchers to work on understanding the association of hypercalcemia or chronic inflammation leading to development of malignancy or parathyroid adenoma in the presence of hypothyroidism will give future perspective in managing such patients.Case presentationA Islam lady aged 45 years old, diagnosed with hypothyroidism, was evaluated for pregnancy loss and rapid weight gain from 13 years back and started on tablets of levothyroxine 25 µg once daily. She was doing well until the past 2 years; there after she noticed insidious onset of a swelling over anterior aspect of right side of the neck and bone pain in back and lower limbs. Patient underwent routine investigations and was found to have raised serum calcium (11.4 mg/dl) and parathyroid hormone (253 pg/ml). Anti-thyroid peroxidase (TPO) and anti-thyroglobulin (Tg) level were normal. Ultrasounds showed multiple nodules in both lobe of thyroid and left inferior parathyroid adenoma. The patient underwent total thyroidectomy with left inferior parathyroidectomy, and final histopathology showed features of subacute granulomatous thyroiditis along with hurthle cell change in right lobe of thyroid. The left lobe additionally showed necrotizing epitheloid cell granulomas, which on Zeihl–Neelson staining revealed presence of acid-fast bacilli. Sections from the isthmus show a focus of papillary thyroid microcarcinoma. The left inferior parathyroid gland sent as a frozen sample was found to be parathyroid adenoma. On 6-month follow-up, the patient was feeling much relief in bone pain and tolerating antitubercular drugs uneventfully.ConclusionCoexistence of parathyroid adenoma, nonmedullary thyroid carcinoma, and thyroid tuberculosis is extremely rare. Surgery is curative for hyper parathyroidism and thyroid carcinoma. Thyroid tuberculosis responds well to current antitubercular drugs. Its etiology needs to be explored more; the probable hypothesis is chronic inflammation due to latent tuberculosis might leads to development of thyroid carcinoma and parathyroid adenoma. Further studies need to be done for better understanding of underlying mechanism and better management options for such patients. To the best of our knowledge, similar cases have not been reported.

On Vascular Lesions of the Thyroid Gland with Emphasis on Intrathyroidal Hemangioma: Clinicopathologic Characterization of Two Cases and Review of the Literature

Mesenchymal neoplasms of the thyroid gland are exceptionally rare accounting for less than 0.5% of all intrathyroidal tumors with hemangiomas comprising merely 6% of them. The clinicopathologic characteristics of two additional examples of thyroid hemangioma together with a thorough review of the pertinent literature are presented. A 62-year-old man and an 18-year-old woman presented with asymptomatic, soft-to-palpation, mobile nodules of the right thyroid lobe classified as TI-RADS 5 and TI-RADS 4, respectively, on ultrasound imaging. Microscopically, lesions featured a circumscribed, unencapsulated, lobular proliferation of variably-sized, congested, vascular channels lined by a single layer of flattened, cytologically bland endothelial cells, together with interspersed residual follicles. Vascular endothelial cells were strongly positive for CD31, CD34 and ERG, and negative for pancytokeratin AE1/AE3, TTF1, and PAX8. A diagnosis of cavernous hemangioma was rendered in the clinical setting of Hashimoto thyroiditis and follicular adenoma, respectively. Following inclusion of the current cases, a total of 53 intrathyroidal hemangiomas were identified in the literature with a patient mean age of 48.9 years (range = 0.17-84) and a slight female predilection (F:M = 1.4:1). A proclivity for the right thyroid lobe (59.6%) was noted with the striking majority of cases exhibiting features of cavernous hemangioma (95.2%). Prognosis is favorable and surgical resection is considered curative. The occasionally alarming clinical presentation in conjunction with absence of pathognomonic imaging features and limited diagnostic accuracy of FNA cytopathology for such lesions renders surgical intervention necessary for definitive diagnosis of intrathyroidal hemangiomas and exclusion of other epithelial and non-epithelial pathologic entities.

Tomographic and ultrasound evaluation of the thyroid gland in pet guinea pigs.

There has been increasing interest in the literature on primary thyroid diseases in guinea pigs, which are believed to be underdiagnosed. This study describes the size and characteristics of the thyroid gland on ultrasound (US) and CT examinations in the guinea pig (Cavia porcellus) without evidence of thyroid pathology and examines the possible use of US as a routine examination for thyroid diseases. This prospective and anatomical study included 20 guinea pigs that underwent CT for dental pathologies and US for thyroid gland (TG) examination. Based on US and CT images, this study evaluated the thyroid lobe dimensions (length, height, and width) and shape. Echogenicity and homogeneity were assessed on US images, and attenuation values (HU) and homogeneity were evaluated on CT images. All animals underwent CT and US examinations under anesthesia. Thyroid lobes appeared more frequently as fusiform on CT (65%) and oval on US scans (67.5%). The attenuation values on CT scans were homogeneous. On the US scans, the TG was more frequently hypoechoic. No statistically significant differences were found between the size of the right and left thyroid lobes, both with CT and US. A statistically significant difference was found between the length values on CT and US. The US and CT thyroid gland dimensions, shape, and appearance were described. Both CT and US are useful techniques for evaluating the TG in guinea pigs.

Anaplastic transformation of papillary thyroid carcinoma in the cervical lymph nodes showing a variety of rhabdoid, epithelioid and spindle cell phenotype

Abstract Introduction/Objective Anaplastic thyroid carcinoma (ATC) is a rare undifferentiated tumor of thyroid follicular cells with a dismal prognosis. Most ATCs derive from pre-existing, well-differentiated thyroid carcinomas, most commonly papillary thyroid carcinoma (PTC). In nearly all instances, ATC arises within the thyroid gland. Completely divergent morphologies of this tumor between the bilateral cervical nodes as well as the almost exclusive presence of ATC in the metastatic and nodal locations are very unusual and are reported here. Methods/Case Report A 67-year-old man presented with a rapidly enlarging left cervical mass, hoarseness, dry cough, and drooping left eye. MRI demonstrated bilateral enlarged cervical lymph nodes spanning levels II to V, and nodules in thyroid lobes. Subsequent total thyroidectomy with bilateral radical neck dissection was performed. Histologically, the left lateral cervical masses revealed undifferentiated tumor cells with rhabdoid, epithelioid and spindle cells features. Conversely, the tumor within the thyroid lobes and the right cervical lymph nodes exhibited PTC with tall cell features. All undifferentiated tumor components stained positive with AE1-3, CK7, PAX8, and negative with thyroglobulin, EMA, CD34, S100, Melan-A, Sox 10, desmin, myogenin, and P40. INI-1 staining is retained. Only the spindle cell component stained positive with TTF1. Based on the morphology and immunoprofile, a diagnosis of anaplastic thyroid carcinoma was rendred. Results (if a Case Study enter NA) NA Conclusion Diagnosing anaplastic thyroid carcinoma outside the thyroid lesion can be challenging. In our case, only extensive sampling of the surgical specimen identified a small focus of well-differentiated PTC, staining positive for thyroglobulin, in the left cervical anaplastic carcinoma component, identifying its origin. This case adds to the scarce literature documenting unilateral anaplastic transformation in the left cervical metastatic lymph nodes, while the right cervical lymph nodes contained pure well differentiated PTC. This represents a significant potential pitfall in presurgical fine needle aspiration (FNA) evaluation of patients with ATC.

Effects of Different Fields of View and Rotation Angles on Radiation Doses to Highly Radiosensitive Organs in Children Using Dental Cone Beam Computed Tomography

Dental cone beam computed tomography (CBCT) is a diverse 3D X-ray imaging technique that has enabled clear visualization of the teeth and surrounding structures. The most common diagnostic purpose of dental CBCT examination in children is ectopic eruption and impacted teeth, and a small field of view (FOV) is often used. Since it is difficult for children to control their body movements, reducing the rotation angle is effective. However, no studies have examined the effects of different rotation angles on radiation doses to highly radiosensitive organs in children using small FOVs. The purpose of this study was to examine the effects of small FOVs (4 × 4 cm and 6 × 6 cm) and rotation angles (360° and 180°) on doses that highly sensitize organs in children using dental CBCT. The entrance surface doses to lenses, thyroid lobes, parotid glands, and sublingual glands of a pediatric whole-body phantom were measured. By reducing the FOV from 6 × 6 cm to 4 × 4 cm, the dose to the sublingual gland could be significantly decreased. Additionally, by reducing the rotation angle from 360° to 180°, the lens dose can be decreased significantly. As the rate of dose reduction varies among organs, it is important to consider the relative positions of different organs with respect to the FOV and the trajectory of the X-ray tube.

Hipertensão arterial resistente: um desafio diagnóstico

Introduction: Primary hyperaldosteronism is a leading cause of secondary arterial hypertension, affecting approximately 10% to 20% of the hypertensive population worldwide and in Brazil. This condition involves excessive aldosterone production due to factors such as adrenal adenoma, hyperplasia, or, less commonly, adrenal carcinoma and familial hyperaldosteronism. This study reports a case of resistant hypertension secondary to aldosterone-producing adenoma. Clinical Case: A 70-year-old male patient presented with episodes of dizziness, syncope, cramps, and asthenia. His medical history included resistant hypertension for over 30 years, despite treatment with five classes of antihypertensive medications. Additionally, he had a history of dyslipidemia, type 2 diabetes mellitus, non-dialysis chronic renal failure, and obstructive coronary arterydisease. Physical examination showed a BMI of 29 kg/m² (overweight), mean blood pressure of 140/90 mmHg (right arm) and 150/100 mmHg (left arm), and palpable nodules in both thyroid lobes, classified as Bethesda V based on aspiration cytopathology. Subsequently, he underwent total thyroidectomy and lymph node dissection. Laboratory tests revealed high plasma aldosterone levels with suppressed renin and an elevated aldosterone-renin ratio, raising suspicion of primary hyperaldosteronism. This diagnosis was confirmed by a computed tomography scan, which identified a 1.2 cm nodule in the right adrenal gland consistent with an adenoma. The patient underwent unilateral laparoscopic adrenalectomy. Two years post-surgery, the patient’s blood pressure was well-controlled with three antihypertensive medications, and his blood sugar, aldosterone, and renin levels were normal. Discussion and Conclusion: Most patients undergoing unilateral adrenalectomy for aldosterone-producing adenomas experience significant clinical improvement. Early screening and diagnosis of primary hyperaldosteronism are crucial for effective management, reducing the risk of complications in the cardiovascular and renal systems.

8385 Coexistence of Parathyroid Adenoma & Papillary Thyroid Cancer: A Rare Case Report

Abstract Disclosure: K. Dash: None. S. Verma: None. U. Ayyagari: None. M. Roy: None. S. Rathore: None. Prevalence of primary hyperparathyroidism (pHPT) ranges from 0.1- 0.4% in general population. Nodular thyroid disease is an increasingly common incidental diagnosis due to widespread use of ultrasound. Papillary thyroid cancer (PTC) is the most common cancer of thyroid gland. Here we report a 53 year old post-menopausal woman presented with weight loss, generalised body aches, arthralgia, myalgia, and proximal muscle weakness. She was hypertensive and clinically euthyroid. Physical examination revealed generalized tenderness all over the body but no thyroid or parathyroid nodules on palpation. Biochemical evaluation showed hypercalcemia 12.1mg/dl (8.4-10.2mg/dl), PTH>2000pg/ml (14-72pg/ml), ALP-1855 U/L (40–125 U/L), decreased phosphorous of 2.4mg/dl (25-4.6 mg/dl), and vitamin-D of 46 nmol/L ( 75-250 nmol/L). USG neck revealed a heterogeneous lesion at the lower pole of right lobe of thyroid gland & two small hypoechoic nodules seen in the right lobe of thyroid gland. FNAC from nodules was inconclusive. USG abdomen revealed nephrocalcinosis. DEXA scan showed severe osteoporosis. Tc99mSestamibi SPECT-CT showed uptake at lower pole of right lobe of thyroid. On exploration, two nodules were palpated in the right lobe of the thyroid and simultaneous right hemi-thyroidectomy was performed. Histopathologic report confirmed parathyroid adenoma (figure 1) as well as presence of carcinoma in the two nodules: one was a papillary thyroid cancer (Classic variant) and the other a follicular variant of papillary thyroid carcinoma (figure 2). Margins were negative for malignancy. She was treated with levothyroxine to maintain TSH <0.1U/L and followed up with annual ultrasound screening. At 2 year follow up, patient was symptom free with improved T score on DEXA scan and no nodule over residual thyroid gland. Discussion: Co-existence of pHPT and PTC ranges from 2.3-4.3%. The use of ultrasound neck as a routine imaging modality for localisation of parathyroid adenoma allows detection of thyroid nodules. Benign and/or malignant thyroid nodules are commonly seen in patients with pHPT and this can range from 2-15%. Women have higher risk for co-existence. The relationship between the two diseases is thought to be incidental. Some authors have suggested possible role of shared genes, embryological factors, transcription factors, vitamin-D deficiency and hyperparathyroidism that could lead to activation of angiogenic factors and carcinogenesis. Fig. 1. Parathyroid adenoma. (a)Tc99m sestamibi scan showing right inferior parathyroid adenoma (b) Parathyroid adenoma (400x high power) comprising predominantly of Chief cells with mild pleomorphism. Fig. 2. Histopathology of PTC. (a)Papillary Carcinoma thyroid. 10xPhotomicrograph showing areas of calcification. (b) Papillary Carcinoma thyroid. Photomicrograph showing thyroid with papillary pattern with areas of infiltration. Presentation: 6/1/2024

8141 A Rare Case of Follicular Adenoma with Osseous Metaplasia and Mature Bone Formation- Is Surveillance Important?

Abstract Disclosure: K. Madani: None. Y. Al-Khazraji: None. D.H. Sacoto: None. G.K. Rai: None. R. Belokovskaya: None. A.A. Franco-Akel, MD: None. Osseous metaplasia and mature bone formation (MBF) are common in malignant thyroid and parathyroid tumors. It is very unusual to have MBF in a benign tumor-like follicular adenoma, as in the case we describe. We found only twelve such cases reported in the literature, and none addressed the cancer risk or need for surveillance for the development of potential malignancy. Thus, further studies are required to investigate the need for surveillance in patients not undergoing excision and in those with remnant thyroid tissue post-removal of the adenoma for recurrence. A 43-year-old female with history of hyperlipidemia and hypothyroidism had an incidental finding of midline neck mass during the evaluation of a left upper extremity lipoma. Ultrasound of the neck showed two nodules in the Left (L) thyroid lobe: a complex nodule measured 2.2 x 1.2 x 2.1 cm and a calcified nodule measuring 1.5 x 0.8 x 0.6 cm. MRI of the neck revealed a 1.9 cm heterogeneously enhancing nodule in the mid to lower pole of the L thyroid lobe. The patient had symptoms suggestive of compression, such as dysphagia, odynophagia, and hoarseness; thus, left hemothyroidectomy was performed. Tissue biopsy was notable for follicular adenoma with osseous metaplasia and mature bone formation. The patient remained clinically and biochemically euthyroid, with only mildly elevated thyrotropin level, and treatment with levothyroxine 25 mcg once daily was initiated. On post-surgical follow-up, there was a lack of data to support close monitoring modality and strategy for the remnant thyroid lobe and neck nodal compartments. We concluded with the patient to follow up in a clinical visit for a physical exam of the neck and to obtain a follow-up sonogram at an interval of six months, in addition to monitoring TSH levels to guide hypothyroidism therapy. Osseous metaplasia has not been established as a premalignant condition, but in certain tissues like the esophagus, metaplasia is a risk factor for malignant conversion, for instance, in Barrett’s esophagus leading to esophageal adenocarcinoma. Moreover, MBF in thyroid tissue has been attributed to the activity of basic fibroblast growth factor (bFGF) and bone morphogenetic protein-2 (BMP-2), which are linked with mitogenesis and tumorigenesis. Thus, the question arises if post-excision surveillance is required in patients with a history of osseous metaplasia in remnant thyroid tissue post-lobectomy or partial thyroidectomy. At this point, more epidemiological data on similar cases may help us understand the true risk of this clinical scenario, in order to develop a reasonable approach for surveillance. Presentation: 6/3/2024

8578 Papillary Thyroid Carcinoma in Autonomous Nodule with Low Risk Characteristics in Adolescent

Abstract Disclosure: A. Aponte Velez: None. M.M. Mangual Garcia: None. Thyroid nodules in children are uncommon but are known to carry a greater risk of malignancy than adult thyroid nodules. Additionally, differentiated thyroid cancer (DTC) in children is more commonly found with extrathyroidal extension and metastases which makes the approach and treatment similar but with important differences. The incidence of DTC in children is increasing, making a personalized evaluation of thyroid nodules in pediatric patients even more valuable. Guidelines recommend evaluation of nodules based on sonographic characteristics rather than size of nodule. However, not having worrisome sonographic characteristics may not be as reassuring as in adult patients. A 13 year old female patient presented with a palpable non tender right sided solid thyroid mass. She had no family history of thyroid cancer or history of irradiation. Thyroid function tests were remarkable for TSH:0.017 and positive thyroid stimulating immunoglobulin. Thyroid Ultrasound findings described heterogenous parenchyma with multiple discrete lesions on right thyroid lobe with a dominant solid isoechoic nodule at upper lobe measuring 2.1 x 3.5 x 1.9cm and a smaller nodule in lower lobe. Thyroid scan demonstrated a large functional hot nodule occupying most of right thyroid lobe with suppression of rest of thyroid parenchyma. Ultrasound guided FNA was performed of this lesion and results were negative for malignancy. Patient underwent total thyroidectomy with pathology report revealing right thyroid nodule encapsulated classical variant of papillary thyroid carcinoma. No lymph node metastases were identified. Non neoplastic thyroid parenchyma revealed chronic lymphocytic thyroiditis. Patient underwent radioiodine therapy with Whole Body Scan post radioiodine therapy demonstrating focal increased radionuclide localization at in region of neck consistent with functional thyroid tissue. There was no evidence of metastatic disease. In children, risk of malignancy is underestimated in ultrasonography and cytology. In this patient, papillary thyroid carcinoma was identified despite being stratified as having low risk of malignancy based on ultrasonography characteristics, hyperfunctioning nodule in scintigraphy study along with negative FNA results. Hyperfunctional nodules are usually reassuring for low risk of malignancy but rarely DTC can be found as in our patient. Guidelines agree that FNA is not recommended in functional nodules as surgical resection is the main therapy in children. However, surgery may be deferred if subclinical hyperthyroidism and low risk sonographic characteristics are present such as in our patient. If surgery had been deferred, based on low risk of malignancy, the risk of progression of disease would have been higher. Prognosis of DTC in children is good but the recurrence rate along with morbidity at such a young age may improve with more studies of DTC in children. Presentation: 6/2/2024

8477 Medullary Thyroid Carcinoma Masquerading as a Cold Nodule in a Patient With Graves' Disease

Abstract Disclosure: T. Umashree: None. K.J. Farooqui: None. A. Mithal: None. Background: Only a handful of cases of MTC have been reported in the setting of Graves’ disease. Clinical Case: A 38 year old lady presented with symptoms of significant weight loss and palpitations for past six months. Thyromegaly was present, with non tender left lobe enlargement of about 3x3 cm. On further probing it was found that her father had been operated for thyroid cancer 22 years ago, the type of which patient was not aware of. TFTs reflected a thyroxtoxic state (TSH -<0.01mIU/mL [0.34-5.6] FT4 - 3.38 ng/dL [0.58-1.64] FT3 - 8.46 pg/mL [2.6-4.2]) and TRAb was positive (8.74 IU/L [<1.22]). USG neck revealed a hypoechoic lesion of 18x18x13 mm in left lobe thyroid with internal calcifications, with multiple bilateral non-significant lymph nodes. Technetium99 (Tc99) scan showed an enlarged left lobe, with diffuse thyroid uptake at 20 minutes of 4%, and a well-defined photopenic area in left lobe, corresponding to the nodule seen on USG. FNAC of the nodule was suggestive of Hürthle cell neoplasm and patient underwent left hemithyroidectomy. Surprisingly, HPE was consistent with medullary thyroid cancer. Serum calcitonin was raised at 148 pg/mL (N<4.8 for females) and plasma free metanephrines and normetanephrine were normal. F-18 DOPA PET CT showed uptake in residual right lobe of thyroid only, no other abnormal uptake was seen. She underwent completion thyroidectomy with central compartment clearance and is now under regular follow up. Genetic analysis showed RET gene mutation of Cys634Ser, which is heterozygous for MTC. Cold nodules in Graves’ disease should be viewed with suspicion, and while PTC and FTC have been reported more commonly, MTC is extremely rare in this setting. A calcitonin washout of the FNAC may have prevented this patient from undergoing two surgeries. Moreover, Hürthle cell change can also occur in C-cells of the thyroid, not just the follicular cells. Lastly, given the history of thyroid cancer in her father, index of suspicion of MTC should have been higher in this patient. Conclusion: Cold nodules in Graves’ Disease may be malignant, and should always be examined by FNAC. Though MTC is rare, it is not unknown in Grave’s disease. Presentation: 6/3/2024

6645 Paraganglioma or Benign Ectopic Thyroid Tissue?

Abstract Disclosure: J.A. Dower: None. R. MacLeod: None. B. Cardoso: None. C. Matouk: None. S. Mehra: None. G. Riccio: None. L. Williams: None. S.K. Majumdar: None. Introduction: During gestation, cells destined to form the thyroid descend through the thyroglossal duct; ectopic thyroid tissue may deposit anywhere along this route from tongue base to mediastinum (1). Less commonly, thyroid tissue can be found lateral to the duct, either alone or in association with a lymph node (2). We present a case of lateral ectopic thyroid tissue mimicking paraganglioma. Clinical Case: A healthy 32-year-old woman presented to ENT with cervical adenopathy persisting for several months after a flulike illness. FNA showed no evidence of malignancy. A neck CT with contrast ordered for further evaluation revealed a 3.2 x 2.3 x 1.5 cm enhancing mass within the right carotid space, splaying the external and internal carotid artery branches, most concerning for paraganglioma. A second, smaller lesion was noted inferiorly. Neck MRI confirmed these findings and revealed a subcentimeter T2 lesion within the right thyroid lobe. The patient was referred to endocrine for further workup. She had no symptoms of sympathetic hyperactivity and no family history suggestive of pheochromocytoma or paraganglioma. Biochemical workup was largely within normal limits: plasma metanephrines 53 pg/mL (57), normetanephrines 94 pg/mL (148), calcitonin <2 pg/mL, TSH 1.210 uIU/mL (0.27-4.2), FT4 1.52 ng/dL (0.8-1.7). Follow-up 24-h urine studies were also unremarkable: metanephrines 166 mcg (36-190), normetanephrines 159 mcg (35-482). Brain MRI, chest CT, and abdomen/pelvis MRI were negative for additional masses. DOTATATE PET/CT was completed to determine if the thyroid lesion was another potential paraganglioma requiring resection versus a nodule amenable to biopsy; uptake was confined to the carotid space lesions, so FNA of the thyroid nodule was considered safe. Thyroid FNA revealed FLUS with genetic testing indicating low likelihood of malignancy. The patient underwent tumor embolization followed by neck dissection with successful removal of both the larger and smaller masses identified on imaging. Frozen and permanent tissue section revealed that both masses consisted of benign thyroid tissue without associated lymphoid tissue. The patient experienced jaw pain with eating after surgery and is under consideration for Botox injection. Conclusion: Benign thyroid tissue can deposit in unexpected places, mimicking malignancy and paraganglioma, alike. Even a very thorough workup can mistake the identity of a mysterious mass; only the tissue itself can make the diagnosis.

8747 A Rare Receptor Resistance with Paradoxical Outcomes!

Abstract Disclosure: I. Patoli: None. S. Batool: None. A.S. Gill: None. A. Makdissi: None. Introduction: Resistance to thyroid hormone receptor is an uncommon cause of abnormal TFTs. (1) We present an interesting case of THRB resistance with cardiac arrhythmia (CA). Clinical Case: 46-year-old man with history of atrial fibrillation (Afib) was referred to endocrinology for evaluation of abnormal TFTs and thyroid nodule. He had a recent hospital admission for Afib with rapid ventricular response; 3 years ago, he was treated with amiodarone for 2 months. TFTs revealed normal TSH of 1.375, elevated FT4 of 2.76 (normal ranges 0.55-4.78 and 0.89-1.76, respectively). Neck CT scan showed large peripherally enhancing centrally necrotic mass with calcification encompassing nearly the entirety of left thyroid lobe measuring 2.2 x 3.6 x 4.6 cm. A 0.8 cm hypodensity within right thyroid lobe also visualized. Thyroid ultrasound showed nodules bilaterally with the largest one in the lower pole of left lobe. FNA biopsy showed Bethesda category- II benign, benign appearing follicular cells and abundant colloid. Repeat labs showed similar results with persistently elevated free T4 (2.56) with equilibrium dialysis, normal alpha subunit, normal TSH (2.14) with human anti-mouse antibody (HAMA) antibody was negative. Alpha subunit:TSH ratio was <1. He remained clinically euthyroid over the course of 1.5 year but repeat labs at that time indicated that TSH had increased to 17 with elevated free T4 (2.6) . MRI brain ruled out TSH secreting adenoma. He reported thyroid abnormalities in son and brother but was unable to provide details. He was referred for genetic screening which showed THRB with pathogenic variant: c.9628> G (p.Y321C). Conclusion: THRB resistance is an uncommonly diagnosed modality in endocrinology. The genes encoding thyroid hormone receptors are THRα gene and THRβ gene (2). Patients with inherited THRB pathogenic variants present with resistance to thyroid hormone and often enlarged thyroid gland. Interestingly, despite having receptor resistance, patients may manifest with CA. This is hypothesized to be due to elevated T4 and T3 concentration in the heart which primarily has higher expression of THRA (3). The diagnosis of thyroid hormone resistance is important to avoid treating asymptomatic patients where treatment is not warranted.

7355 A Case of High-Risk Thyroid Tumor Markers Found in Subcutaneous Thyroid Implants in a Patient with Benign Thyroid Pathology

Abstract Disclosure: J. Fedorko: None. S. Fatima: None. A.P. Amblee: None. C.A. Poku: None. Background: While fine needle aspiration (FNA) remains the primary diagnostic tool for thyroid malignancies, the utilization of molecular markers has become increasingly common in the workup of thyroid nodules. They play a useful role in distinguishing between malignant and benign pathology when cytology is indeterminate and in formulating treatment plans. The vast majority of research for these genetic markers is conducted in cases with thyroid malignancy. However, there have been numerous cases where these genetic markers were identified in benign thyroid tissue. Case: A 73-year-old male with left hemithyroidectomy (benign left nodule) presented 6 years later with new superficial neck nodules along the midline, left thyroid bed and R thyroid lobe. FNA of the right thyroid nodule was benign. Three months later the patient underwent an excision of the midline neck nodules which revealed thyroid tissue arranged in nests of fibrotic tissue without definite features of papillary thyroid carcinoma. Molecular analysis (Thyroseq) was positive for HRAS, E1F1AX and TERT mutations thus metastatic follicular carcinoma was suspected. The patient underwent complete thyroidectomy. Pathology revealed normal thyroid tissue and a diagnosis of thyroid neck implants was made. Given the benign pathology, the plan was for close follow-up with neck imaging every 6 months. Discussion: Thyroid tissue implants can rarely be caused by previous surgical interventions, especially partial thyroidectomy. There is literature documenting similar clinical cases in which subcutaneous thyroid implants are found in patients after undergoing total or subtotal thyroidectomy. In one case series, there were cases in which thyroid implants were discovered 26 years post-surgery, with most of the cases reporting benign pathology. Given our patient’s presentation and clinical history, the possibility remains that his subcutaneous tissue findings were caused by his prior partial thyroidectomy. A recent article reviewed 60 publications and >8000 patients for the prevalence of high-risk tumor markers (RAS mutation, RET/PTC, and PAX8/PPAR-gamma chromosomal rearrangements) in benign thyroid tissue. They concluded that prevalence findings were highly variable, warning providers to exercise caution when using these genetic markers to guide diagnosis and treatment decisions. Conclusion: While certain high-risk genetic tumor markers are increasingly used to help identify thyroid malignancies, it is important to keep in mind that these genetic markers are not exclusively found in cancerous tissue, and should not be used as the sole diagnostic tool for diagnosis and treatment. While it is imperative that metastatic disease is ruled out, it is essential to consider other pathologies when evaluating recurrent thyroid and neck masses in patients with a history of benign thyroid lesions. Presentation: 6/3/2024

7387 A Rare Case Of Concomitant Intrathyroidal Parathyroid Carcinoma With Osteitis Fibrosa Cystica, Masquerading As Oncocytic Thyroid Carcinoma - A Post-operative Diagnosis

Abstract Disclosure: Y. Koh: None. D.E. Chew: None. T.P. Quek: None. Introduction: Parathyroid carcinoma is a rare form of malignancy. An intrathyroidal location of parathyroid carcinoma further complicates the diagnosis as it may be mistakenly presumed to be of thyroid origin instead. We present a case report of an intrathyroidal parathyroid carcinoma which was diagnosed post-total thyroidectomy. Clinical case: A 72-year-old lady was found to have an intrathyroidal mass after presenting with unintentional weight loss and chronic constipation. Ultrasound of the neck showed a 4.0 x 2.9cm markedly hypoechoic solid mass in the mid-lower right thyroid lobe. Fine needle aspiration of the mass was suspicious for an oncocytic neoplasm. She underwent total thyroidectomy with central neck dissection for concerns of oncocytic thyroid carcinoma. Intraoperatively, a 4cm right hard intrathyroidal nodule invading into the right recurrent laryngeal nerve was observed. All 4 parathyroids were identified and preserved. Post-operatively, routine biochemistry to monitor for hypocalcemia showed hypercalcemia instead. This quickly transitioned into hypocalcemia on post-operative day 4, with biochemistry supportive of hungry bone syndrome [adjusted calcium 2.05mmol/L [normal range (NR) 2.15-2.5], phosphate 0.6mmol/L (NR 0.8-1.4), PTH 8.2pmol/L (NR 0.8-6.8), 25-OH vitamin D 18ug/L (NR 30-100)]. She was started on oral calcium carbonate, calcitriol and cholecalciferol aiming for normocalcemia. Evidence for underlying primary hyperparathyroidism were sought for, which showed osteitis fibrosa cystica, severe osteoporosis and an ossifying fibroma of the mandible, suggesting underlying hyperparathyroidism-jaw tumour-syndrome. The intra-operative histology was reported as oncocytic carcinoma with angio- and perineural invasion, presumed to be thyroid in origin. Given our suspicion of underlying primary hyperparathyroidism, we requested our pathology colleagues to perform additional immunochemical stains, which stained diffusely positive for parathyroid hormone, GATA3 but were negative for thyroglobulin, thyroid transcriptor factor-1, confirming its parathyroid origin. Her hungry bone syndrome resolved 22 weeks post-operatively. Till present (14 months post-operatively), her calcium and PTH levels remain normal and ultrasound of the neck did not reveal any evidence of recurrence. She declined genetic screening. Clinical Lesson: A high index of suspicion is required for the diagnosis of parathyroid carcinoma. In a patient who presents with constitutional symptoms and a neck mass, it is imperative to consider parathyroid disease as a differential diagnosis. A lesion with oncocytic morphology may be of parathyroid or thyroid origin, and the use of immunochemical stains can help differentiate them. Effective communication between clinicians and pathologists is essential in clinching the correct cytopathological diagnosis. Presentation: 6/3/2024

9365 Now You See Me: The Case Of The Ectopic Thyroid

Abstract Disclosure: S.I. Suarez: None. S.K. Majumdar: None. Introduction: Lingual thyroid refers to ectopic thyroid tissue located at the base of the tongue or within the thyroglossal tract secondary to failed descent to its usual site (1). Ninety percent of ectopic thyroid glands are found at the base of the tongue and can occur in 1 in every 100,000 patients (2, 3). Clinical presentations commonly relate to obstruction of the oropharynx, and patients may experience dysphagia or throat fullness/discomfort (1). We present a case of lingual thyroid presenting as dysphagia and progressive hypothyroidism. Case: A 38-year-old woman with a history of HLD and hypothyroidism was referred for evaluation of ectopic thyroid tissue. She presented to her provider for concerns of dysphagia, neck swelling, and excessive hair thinning/loss. She had a recent increase in levothyroxine dose from 112 to 125 mcg after a TSH of 20.4 (0.27 to 4.2 uIU/mL). Repeat tests showed a TSH of 29.4 and a free T4 level of 0.79 (0.8 to 1.7 ng/dL). She denied use of thyrotoxic medications, any radiation or surgeries to head or neck, personal or family history of autoimmune disorders. Thyroid was nonpalpable on exam. A thyroid US 5 years prior showed a 15 x 5 x 5 mm right lobe and 12 x 8 x 5 mm left lobe. CT scan of soft tissue of neck with contrast showed a 14 x 13 x 15 mm hyperintense nodular lesion midline along the anterior glossoepiglottic fold at the foramen cecum, with an 8 x 11 x 8 mm hyperintense nodular lesion at midline abutting the anterior body of the hyoid bone, and no thyroid tissue in the expected thyroid bed, findings consistent with ectopic thyroid tissue along the expected thyroglossal duct. Furthermore, an I-123 scan with SPECT confirmed the ectopic thyroid tissue. What was thought to be thyroid lobes on previous thyroid US was likely paratracheal fat. Levothyroxine was increased to 137 mcg per day with improvement at 2 months (TSH 10.4, Free T4 0.91). Adjusting levothyroxine replacement was the primary intervention, given that elevated TSH may result in hypertrophy of lingual thyroid tissue resulting in dysphagia, particularly if there is no mass or suspicion of cancer on imaging. Conclusion Hypothyroidism presenting with dysphagia in the absence of goiter, previous thyroid surgery, or detectable thyroid tissue should warrant consideration of ectopic thyroid tissue and initial therapy should be directed towards normalizing TSH in conjunction with excluding malignant causes.

5118 When Thyroid Gland Is Not Made Of Thyroid Cells

Abstract Disclosure: A. Bulut: None. L. Ma: None. J.P. Noordzij: None. S.Y. Lee: None. Introduction: Neurofibroma is a type of peripheral nerve tumor that can arise sporadically or be a part of neurofibromatosis type 1 (NF1), a rare genetic disorder. Neurofibromas within the thyroid gland are extremely rare. Here, we present the fifth reported case of primary neurofibroma of thyroid gland. Case: A 60-year-old woman with history of systemic lupus erythematosus and hypertension presented with enlargement of left thyroid gland. She was diagnosed with Graves’ disease 40 years ago, which was treated with right thyroid lobectomy one year after the initial diagnosis. Five years after the surgery, she had recurrence of her symptoms and received radioactive iodine ablation with subsequent hypothyroidism. On presentation to endocrine clinic, she had thyroid ultrasound (US), which showed surgically absent right thyroid lobe and enlarged heterogenous left thyroid lobe measuring 5.1 cm x 3.8 cm x 3.9 cm with scant blood flow without discrete nodules. In interim, patient developed dysphagia and globus sensation. Repeat thyroid US showed enlargement of left lobe to 5.6 cm x 3.7 cm x 4.7 cm. Patient underwent completion thyroidectomy. Surgical pathology showed neurofibroma (S-100+, CD34+ and MSA-) without any thyroid parenchyma. Whole-body scan revealed no other evidence of tumors. Patient was referred for genetic analysis. Discussion: Neurofibromas are benign peripheral nerve system tumors primarily consist of Schwann cells along with other components of perineurium. They can occur as a sporadic lesion which accounts for 90% of solitary neurofibroma cases or be a part of NF1 on rare occasions. NF1 is an autosomal dominant genetic disorder due to germline mutation in NF1 gene located on chromosome 17q11.2, whose manifestations include café-au-lait macules, Lisch nodules, skeletal abnormalities, neurological deficits, and other benign and malignant tumors. Neurofibromas are the hallmarks of NF1. There are only few cases in the literature reported neurofibromas adjacent to or originating from thyroid gland. To the best of our knowledge, there have been only four other cases reporting primary neurofibroma of thyroid gland, one of which developed from thyroid capsule. Our patient most likely has primary neurofibroma of thyroid gland given the lack of syndromic features, however, genetic testing is needed in order to rule out NF1. In conclusion, clinicians should consider neurofibroma in their differential in cases of enlarging thyroid gland or nodules, especially in the presence of other clinical features. Presentation: 6/1/2024

5118 When Thyroid Gland is Not Made of Thyroid Cells

Abstract Disclosure: A. Bulut: None. L. Ma: None. J.P. Noordzij: None. S.Y. Lee: None. Introduction: Neurofibroma is a type of peripheral nerve tumor that can arise sporadically or be a part of neurofibromatosis type 1 (NF1), a rare genetic disorder. Neurofibromas within the thyroid gland are extremely rare. Here, we present the fifth reported case of primary neurofibroma of thyroid gland. Case: A 60-year-old woman with history of systemic lupus erythematosus and hypertension presented with enlargement of left thyroid gland. She was diagnosed with Graves’ disease 40 years ago, which was treated with right thyroid lobectomy one year after the initial diagnosis. Five years after the surgery, she had recurrence of her symptoms and received radioactive iodine ablation with subsequent hypothyroidism. On presentation to endocrine clinic, she had thyroid ultrasound (US), which showed surgically absent right thyroid lobe and enlarged heterogenous left thyroid lobe measuring 5.1 cm x 3.8 cm x 3.9 cm with scant blood flow without discrete nodules. In interim, patient developed dysphagia and globus sensation. Repeat thyroid US showed enlargement of left lobe to 5.6 cm x 3.7 cm x 4.7 cm. Patient underwent completion thyroidectomy. Surgical pathology showed neurofibroma (S-100+, CD34+ and MSA-) without any thyroid parenchyma. Whole-body scan revealed no other evidence of tumors. Patient was referred for genetic analysis. Discussion: Neurofibromas are benign peripheral nerve system tumors primarily consist of Schwann cells along with other components of perineurium. They can occur as a sporadic lesion which accounts for 90% of solitary neurofibroma cases or be a part of NF1 on rare occasions. NF1 is an autosomal dominant genetic disorder due to germline mutation in NF1 gene located on chromosome 17q11.2, whose manifestations include café-au-lait macules, Lisch nodules, skeletal abnormalities, neurological deficits, and other benign and malignant tumors. Neurofibromas are the hallmarks of NF1. There are only few cases in the literature reported neurofibromas adjacent to or originating from thyroid gland. To the best of our knowledge, there have been only four other cases reporting primary neurofibroma of thyroid gland, one of which developed from thyroid capsule. Our patient most likely has primary neurofibroma of thyroid gland given the lack of syndromic features, however, genetic testing is needed in order to rule out NF1. In conclusion, clinicians should consider neurofibroma in their differential in cases of enlarging thyroid gland or nodules, especially in the presence of other clinical features. Presentation: 6/1/2024