Low-grade Neuroendocrine Tumors Research Articles

A Curious Case of Pancreatoblastoma in an Older Age Woman

Abstract Introduction/Objective Pancreatoblastoma is a malignant epithelial neoplasm of the pancreas and displays multiple lines of differentiation with acinar differentiation as the predominant pattern. The squamoid nests are considered a defining component of pancreatoblastoma. Pancreatoblastoma is seen most often in children, however, rare cases in adults have been described in the literature. In children, most pancreatoblastomas are indolent and curable, however, the prognosis is worse in adults due to the presence of frequent metastasis. Methods/Case Report We report an interesting case of pancreatoblastoma in a 65-year-old woman with no pertinent medical history who presented with abdominal discomfort. MRI abdomen showed an 11.3 cm mass with central necrosis within the head of the pancreas. Fine-needle aspiration (FNA) of the mass showed monotonous cells with neuroendocrine differentiation and FNA was signed out as a low-grade neuroendocrine tumor (NET). The patient underwent a Whipple resection for a presumed NET. On gross examination, a 14 cm large solid, fleshy, lobulated, partially encapsulated mass was noted in the head of the pancreas. H&E slides on low power showed the tumor composed of highly cellular lobules separated by fibrous bands. Within the lobules, the neoplastic cells predominantly had an acinar differentiation with focal trabecular or solid areas. Dispersed within the tumor were squamoid nests composed of plump to spindle-shaped cells with abundant eosinophilic cytoplasm arranged in whorls. Immunohistochemical stains demonstrated squamoid nests being positive for CK5/6 and had a nuclear-staining pattern with beta-catenin. The remaining tumor was positive for trypsin, chymotrypsin, BCL-10, synaptophysin (focal), chromogranin (focal), and INSM-1 (patchy). On MSK-Impact (next- generation sequencing), a mutation in CTNNB1 was detected. Results (if a Case Study enter NA) NA Conclusion In adults, it is important to consider pancreatoblastoma in the differential diagnoses of solid pancreatic tumors while being cautious not to confuse it with neuroendocrine tumor or acinar cell carcinoma. The presence of squamoid nests is critical for its diagnosis. Making a diagnosis of pancreatoblastoma through FNA or pancreatic biopsy can be exceptionally challenging in cases lacking squamoid nests.

7476 Clinical, Pathological and Biochemical Characteristics of patients with Neuroendocrine Neoplasms (NENs) at a University Hospital in Belo Horizonte, Brazil

Abstract Disclosure: R.D. Romanowski: None. F.P. Ribeiro: None. T.T. Mello: None. B.S. Soares: None. J.B. Drummond: None. Neuroendocrine neoplasms (NENs) are a group of rare, heterogeneous, and potentially aggressive neoplasms, whose incidence is on the rise, largely due to advances in diagnostic methods that allow for more precise and early identification. A recent comprehensive review focusing on the epidemiology, incidence and prevalence of NENs described global findings, however, it did not include any data from Latin America, particularly after WHO 2019 digestive system tumours classification. Methods: We carried a retrospective analysis in a single center aiming to evaluate different clinical, pathological and biochemical characteristics of a cohort of patients with NENs followed at the Neuroendocrinology Outpatient Clinic of the Federal University of Minas Gerais, Brazil, who were diagnosed between the years of 2004 and 2023. Results: The study sample (n=30) included 13 female patients (43%). The median (range) age at diagnosis was 42 (19-73) years old. The most common primary sites observed in the studied population were the pancreas (38%) and the stomach (24%). Twenty three percent of the patients had MEN1 associated NENs. Fourteen tumors (45%) were classified as G1 NENs, 7 tumors (23%) were classified as G2 NENs and two tumors (6,7%) were classified as neuroendocrine carcinomas, while tumor grade classification was not feasible in 7 patients (23%). One third of the patients had functional tumors and metastatic disease was present in 60% of the cases at the time of diagnosis. Conclusion: In general, the epidemiological characteristics here described for our patients align with the global trend. Concerning gender, we observed a higher prevalence of these tumors in men (57%), consistent with the male predominance of up to 3 times over females described around the world. Our patient population seems to be younger than the mean age reported in different case series. Tumoral grade classification was not feasible in a high proportion of patients and despite the high prevalence of well differentiated and low-grade NENs, metastases were commonly seen at diagnosis, in accordance with the literature. Presentation: 6/2/2024

7277 Diabetic Ketoacidosis As The First Manifestation Of Ectopic Cushing’s Syndrome

Abstract Disclosure: R.S. Medeiros: None. Introduction: Ectopic Cushing’s Syndrome (ECS) represents 10-20% of all ACTH-dependent CS, and the majority of cases arise from lung carcinoids. These indolent lesions usually evolve clinically over 6-24 months, whereas carcinomas are associated with faster onset of ECS. Diabetic Ketoacidosis (DKA) as a presenting manifestation of Cushing’s Syndrome (CS) is very rare, with the few cases published to date related to Cushing’s disease. Clinical Case: A 42-year-old woman was admitted in the emergency room with DKA and COVID-19. During stabilization, florid CS was clinically suspected. She reported a 6-month history of secondary amenorrhea, lack of concentration and memory, easy bruising, proximal myopathy with frequent falls evolving to daily life dependency from relatives. She also reported a 2-month diagnosis of dyslipidemia, Diabetes and hypertension, and a diagnosis of atypical pneumonia 6 months ago. Physical exam showed typical cushingoid appearance, especially for marked limb sarcopenia and proximal myopathy. An overnight dexamethasone suppression test (morning cortisol: 25.7 ug/dL), 24h urinary free cortisol (UFC; 1072.5 ug/dL; reference: <176) and serum cortisol at 23h00 (25.5 ug/dL) confirmed CS. ACTH-dependent CS was diagnosed. She had non-suppressible serum cortisol in high dose dexamethasone suppression test, and CRH stimulation test was suggestive of Cushing’s disease only by a 20% rise of cortisol at 30 minutes. Pituitary MRI was normal. Inferior Petrosal Sinus sampling was postponed for several months due to healthcare strikes. The patient started 750 mg of metyrapone in three divided doses but rapidly decreased the dose and stopped it due to clinical resolution of CS, a dramatic improvement of all glucocorticoid-related comorbidities leading to discontinuation of statin, insulin, main oral anti-hyperglycemic and antihypertensive medications, and normal midnight salivary cortisol and 24h UFC. She remained in this eucortisolemic state for 12 months. Thoracic CT scan revealed thymic hyperplasia and a 25x15 mm well-defined nodule in the lingula. A 68Ga-DOTANOC PET/CT showed a single uptake in the same lung region. The patient underwent lingulectomy plus excisional biopsy of interlobar lymph nodes, and pathology revealed a low-grade neuroendocrine tumor (Ki67<2%, <2 mitosis) without involved lymph nodes. The patient is weaning off from physiologic doses of hydrocortisone. Conclusion: DKA can rarely be the presenting manifestation of severe CS, including ECS. Clinicians should suspect on this etiology of DKA based on clinical signs and cumulative morbidity not typical of a young patient. This hint would lead to the expedite implementation of targeted therapies for initial stabilization of the CS patient, and the timely institution of a proper diagnostic approach and definitive treatment of this challenging patients. Presentation: 6/2/2024

Enhancer landscape of lung neuroendocrine tumors reveals regulatory and developmental signatures with potential theranostic implications

Well-differentiated low-grade lung neuroendocrine tumors (lung carcinoids or LNETs) are histopathologically classified as typical and atypical LNETs, but each subtype is still heterogeneous at both the molecular level and its clinical manifestation. Here, we report genome-wide profiles of primary LNETs' cis-regulatory elements by H3K27ac ChIP-seq with matching RNA-seq profiles. Analysis of these regulatory landscapes revealed three regulatory subtypes, independent of the typical/atypical classification. We identified unique differentiation signals that delineate each subtype. The "proneuronal" subtype emerges under the influence of ASCL1, SOX4, and TCF4 transcription factors, embodying a pronounced proneuronal signature. The "luminal-like" subtype is characterized by gain of acetylation at markers of luminal cells and GATA2 activation and loss of LRP5 and OTP. The "HNF+" subtype is characterized by a robust enhancer landscape driven by HNF1A, HNF4A, and FOXA3, with notable acetylation and expression of FGF signaling genes, especially FGFR3 and FGFR4, pivotal components of the FGF pathway. Our findings not only deepen the understanding of LNETs' regulatory and developmental diversity but also spotlight the HNF+ subtype's reliance on FGFR signaling. We demonstrate that targeting this pathway with FGF inhibitors curtails tumor growth both in vitro and in xenograft models, unveiling a potential vulnerability and paving the way for targeted therapies. Overall, our work provides an important resource for studying LNETs to reveal regulatory networks, differentiation signals, and therapeutically relevant dependencies.

Clinicopathological Features of Pediatric Insulinoma: A Single-Centre Study.

Aims/Background: Insulinoma is an extremely rare condition in pediatric patients. This study aims to examine the pathological and clinical characteristics of pediatric insulinoma. Methods: A retrospective, single-center study was conducted involving five pediatric patients diagnosed with insulinoma. The study involved evaluating the postoperative status of the patients during follow-up and analyzing their clinical manifestations, diagnostic work-up, pathological findings, and therapeutic approaches. Results: The study cohort comprised four males and one female, aged between 4 and 9 years. Common symptoms included dizziness and fatigue. The insulinomas were located in various parts of the pancreas: two in the head, one in the neck, one in the body, and one in the tail. After undergoing subtotal pancreatectomy, four patients experienced no side effects during a follow-up period of 41 to 153 months. One patient, who underwent an incomplete pancreatic resection, required ongoing postoperative treatment with 150 mg Creon due to pancreatic enzyme deficiency. Postoperative pathological results indicated that all cases were low-grade neuroendocrine tumours, classified as grade 1 (G1) or grade 2 (G2). Two cases exhibited capsule invasion, and one case showed microvascular invasion. Despite these invasions, no recurrences or metastases have been observed to date. Conclusion: Surgical resection is a viable treatment option for pediatric insulinoma, yielding a favorable prognosis. The presence of capsular and microvascular invasions does not seem to affect the overall prognosis in these cases.

Neuroendocrine Lesions Arising From Mediastinal Teratoma-A Case Report and Literature Review.

Background. Neuroendocrine lesions arising from mediastinal teratomas are rare tumors with only small number of patients reported in literature. The behavior of these lesions appears to be different from traditional neuroendocrine neoplasms. A comprehensive review will be valuable for histologic assessment and treatment planning for similar cases. Case presentation. We present an example of a 57-year-old man who presented with cough. Subsequent work-up revealed an anterior mediastinal mass of 2.1 cm on computed tomography. The patient underwent robot-assisted thoracoscopic thymectomy. Histological examination revealed a mature cystic teratoma with a neuroendocrine component consisting of clusters of tumor cells with round to oval nuclei and a "salt-and-pepper" chromatin pattern. The tumor cells were immunoreactive to cytokeratin, synaptophysin, chromogranin, and INSM1, with a Ki-67 proliferative index of 4%. A histological diagnosis was mature teratoma with well-differentiated low-grade neuroendocrine tumor (carcinoid) was made. The patient was well and without disease after complete surgical excision at 10 months. Literature review. Literature reviewed yielded 13 examples of neuroendocrine lesions arising from mediastinal teratomas. No disease-related mortality was reported, even in lesions with high-grade neuroendocrine, carcinomatous, or immature teratomatous components. Conclusions. Surgical removal is the mainstay of treatment of these lesions, and the presence of a neuroendocrine component does not appear to negatively affect prognosis.

Chromothripsis is a novel biomarker for prognosis and differentiation diagnosis of pancreatic neuroendocrine neoplasms.

This study aimed to identify the role of chromothripsis as a novel biomarker in the prognosis and differentiation diagnosis of pancreatic neuroendocrine neoplasms (pNENs). We conducted next-generation gene sequencing in a cohort of 30 patients with high-grade (G3) pNENs. As a reference, a similar analysis was also performed on 25 patients with low-grade (G1/G2) pancreatic neuroendocrine tumors (pNETs). Chromothripsis and its relationship with clinicopathological features and prognosis were investigated. The results showed that DNA damage response and repair gene alteration and TP53 mutation were found in 29 and 11 patients, respectively. A total of 14 out of 55 patients had chromothripsis involving different chromosomes. Chromothripsis had a close relationship with TP53 alteration and higher grade. In the entire cohort, chromothripsis was associated with a higher risk of distant metastasis; both chromothripsis and metastasis (ENETS Stage IV) suggested a significantly shorter overall survival (OS). Importantly, in the high-grade pNENs group, chromothripsis was the only independent prognostic indicator significantly associated with a shorter OS, other than TP53 alteration or pathological pancreatic neuroendocrine carcinomas (pNECs) diagnosis. Chromothripsis can guide worse prognosis in pNENs, and help differentiate pNECs from high-grade (G3) pNETs.

Distinguishing Bronchial Carcinoid from Benign Bronchocele using 68Ga-DOTATOC PET/CT Imaging.

Bronchial carcinoids are low-grade neuroendocrine tumors with slow growth rates and the potential to spread to nearby lymph nodes. Here we present a challenging case of bronchial carcinoid visualized alongside an adjacent benign bronchocele. Chest computed tomography (CT) identified the endobronchial mass with unclear morphological and diagnostic insights. A differential diagnosis of several benign and malignant etiologies was made. Subsequently, an endobronchial biopsy confirmed lung carcinoid. For better evaluation, a 68Ga-labeled 1,4,7,10-tetraazacyclododecane-N,N',N'',N'''-tetraacetic acid-d-Phe1-Tyr3-octreotide (68Ga-DOTATOC) positron emission tomography/CT scan was performed. The scan revealed a locally confined endobronchial mass with intense 68Ga-DOTATOC expression. Adjacent benign bronchocele was visualized with insignificant 68Ga-DOTATOC expression. Histopathological examination of the resected upper lobe confirmed these findings. This case highlights the importance of somatostatin receptor imaging in accurately identifying the extent of carcinoid tumors in the primary, nodal, and metastatic domains.

Observation for localized, low-grade duodenal neuroendocrine tumors: Equivalent outcomes to resection

Observation for localized, low-grade duodenal neuroendocrine tumors: Equivalent outcomes to resection

Treatment and Long-Term Safety Outcomes of Peptide Receptor Radionuclide Therapy for Metastatic Neuroendocrine Tumours: An Asian Experience

Purpose: Peptide receptor radionuclide therapy (PRRT) is a targeted molecular therapy used to treat neuroendocrine tumours (NETs). It has been shown to be effective and well tolerated in patients with metastatic NETs in several centres in the USA, Europe, and Australia. Tolerability and efficacy data emerging from Asian centres remain few. Epidemiological evidence suggests that there are differences in neuroendocrine neoplasms between the population groups. We aim to describe the treatment and safety outcomes of PRRT in the Asian population. Methods: One hundred and seven (107) patients with metastatic NETs who had undergone PRRT treatment from January 2012 to March 2019 were included in this retrospective study. The response rates using RECIST 1.1 and qualitative analysis were examined. The overall and progression-free survival curves were also evaluated. Results: The median progression-free survival was 49 months. Response assessment after completion of treatment showed that 33 (37.9%) of 87 patients had partial or complete response. Subgroup analysis comparing high- and low-grade NET showed that there was a significant difference in the time to progression curves. Comparison of the number of cycles and progression-free and overall survival also showed a significant difference. Ten patients (9%) had grade 3 or more haematological toxicities. Four patients (4%) had grade 3/4 hepatobiliary toxicities, although the presence of extensive liver metastases was a confounding factor. None of the patients had grade 3/4 acute kidney injury. Conclusion: Our results show that PRRT is safe and effective in the treatment of metastatic NET in the Asian population. There was a significant difference in the progression-free survival curves between low-grade and high-grade NET and in the progression-free and overall survival comparing the number of cycles received.

A Case Series of Choroidal and Orbital Neuroendocrine Tumors: Metastasis: Two Patients Treated With Peptide Radionuclide Therapy.

Neuroendocrine tumors (NETs) are rare cancers with heterogeneous histologies, response to treatments, and prognoses. Majority of these cancers originate in the gastrointestinal tract and metastasize to the liver. We report the cases of 5 patients with low-grade NET disease with rare metastases to the choroids. Two of the patients were treated with peptide receptor radionuclide therapy (lutetium 177 [ 177 Lu]). This is the first report confirming peptide radionuclide therapy safety in patients with low-grade NET with ocular metastases.

Atypical neoplastic solitary focal uptake of 18F-PSMA-1007 in PET/CT in patients with biochemically recurrent prostate cancer

It is established that prostate-specific membrane antigen (PSMA), despite its name, is expressed in many tissues other than the prostate gland, both within physiological conditions and in various pathological processes. Additionally, apart from prostate cancer, other malignant tumors are characterized by increased PSMA expression which, according to many authors, is associated with neoangiogenesis. These factors are reflected in the results of PSMA-radioligand imaging and require comprehensive approach to image interpretation including evaluation of computed tomography and magnetic resonance semiotics. In addition, rare cases of distant visceral prostate cancer metastasis in the form of solitary lesions also should be considered during interpretation of the results of radiologic imaging including positron emission tomography/computed tomography.We present two clinical cases in which positron emission tomography/computed tomography revealed solitary foci of pathological 18F-PSMA-1007 uptake outside the areas of typical metastatic spread (with exception of advanced disease) of prostate cancer, specifically in the stomach wall and the left cerebellar hemisphere. In the first case histological examination results revealed a metachronous low grade neuroendocrine tumor of the stomach, in the second case a metastatic lesion of the cerebellum was diagnosed as part of the underlying disease.

Carcinoid tumorlet/typical carcinoid of the lung: An incidental bronchoscopic finding and cytological dilemma

Carcinoid tumors of the lung are low-grade neuroendocrine tumors with the potential to progress to high-grade tumors. Diagnosing a typical carcinoid of the lung/tumorlet is a tough nut to crack, especially in their early stages when there is no well-defined lesion in the imaging. Besides, differentiating a carcinoid from low-grade adenocarcinomas of the lung cytologically is quite challenging due to their similar morphology. We report a case of typical carcinoid of lung/tumorlet in a 42-year-old male who presented with hemoptysis. Flexible fibreoptic bronchoscopy revealed a bump in the right middle bronchus. Bronchial biopsy showed a cellular smear with a monotonous round to oval bland-looking cells distributed in singles and in acini, having a high nuclear-cytoplasmic ratio, scant cytoplasm, regular round nuclei, and inconspicuous nucleoli. No atypical mitotic figures or necrosis were seen. With these features, a cytological diagnosis of a typical carcinoid was made. Biopsy was not attempted again due to the small size of the lesion and inaccessibility. Serum chromogranin levels were elevated, confirming the diagnosis. The PET scan was unremarkable. The patient was referred to medical oncology for further management. This report will create awareness about diagnosing early carcinoid/tumorlet, especially with the increasing use of bronchoscopy and cytological diagnostic caution of overdiagnosis of malignancy.

Low-Grade Appendiceal Mucinous Neoplasia and Neuroendocrine Appendiceal Synchronous Tumor: A Rare Case Report and Review of Literature for 13 Cases

Low-Grade Appendiceal Mucinous Neoplasia and Neuroendocrine Appendiceal Synchronous Tumor: A Rare Case Report and Review of Literature for 13 Cases

Metastatic Type 1 low-grade gastric neuroendocrine tumor treated with peptide receptor radionuclide therapy in a young adult: a case report.

Metastatic Type 1 low-grade gastric neuroendocrine tumor treated with peptide receptor radionuclide therapy in a young adult: a case report.

Use and perceived utility of [18 F]FDG PET/CT in neuroendocrine neoplasms: A consensus report from the European Neuroendocrine Tumor Society (ENETS) Advisory Board Meeting 2022.

Somatostatin receptor (SST) PET/CT is the gold standard for well-differentiated neuroendocrine tumours (NET) imaging. Higher grades of neuroendocrine neoplasms (NEN) show preferential [18F]FDG (FDG) uptake, and even low-grade NET may de-differentiate over time. FDG PET/CT's prognostic role is widely accepted; however, its impact on clinical decision-making remains controversial and its use varies widely. A questionnaire-based survey on FDG PET/CT use and perceived decision-making utility in NEN was submitted to the ENETS Advisory Board Meeting attendees (November 2022, response rate = 70%). In 3/15 statements, agreement was higher than 75%: (i) FDG was considered useful in NET, irrespective of grade, in case of mis-matched lesions (detectable on diagnostic CT but negative/faintly positive on SST PET/CT), especially if PRRT is contemplated (80%); (ii) in NET G3 if curative surgery is considered (82%); and (iii) in NEC prior to surgery with curative intent (98%). FDG use in NET G3, even in the presence of matched lesions, as a baseline for response assessment was favoured by 74%. Four statements obtained more than 60% consensus: (i) FDG use in NET G3 if locoregional therapy is considered (65%); (ii) in neuroendocrine carcinoma before initiating active therapy as a baseline for response assessment (61%); (iii) biopsy to re-assess tumour grade prior to a change in therapeutic management (68%) upon detection of FDG-positivity on the background of a prior G1-2 NET; (iv) 67% were in favour to reconsider PRRT to treat residual SST-positive lesions after achieving complete remission on FDG of the SST-negative disease component. Multidisciplinary opinion broadly supports the use of FDG PET/CT for characterisation of disease biology and to guide treatment selection across a range of indications, despite the lack of full consensus in many situations. This may reflect existing clinical access due to lack of reimbursement or experience with this investigation, which should be addressed by further research.

NEN in a dish: A patient-derived organoid biobank illuminates potential novel therapeutic opportunities for neuroendocrine neoplasms

Neuroendocrine neoplasms are rare cancers with limited treatment options and preclinical models. In this issue of Cancer Cell, Dayton etal. establish a patient-derived tumor organoid biobank encompassing pulmonary low-grade neuroendocrine tumors (LNETs) and high-grade neuroendocrine carcinomas (LCNECs), identifying novel biomarker-dependent therapeutic vulnerabilities using niche perturbation and drug response assays.

Incidence, Clinicopathological Features and Oncologic Outcome of Appendiceal Neoplasms: A Single-Center Cohort Study

Appendiceal tumors represent a large amalgam of different tumor lineages. The continuous evolution in their pathological classifications has led to some variable recommended attitudes over time. The aim of this study is to review the incidence, clinicopathological characteristics, therapeutic approach and oncological results in this type of tumor at our institution. This is a single-centre retrospective cohort study. Every pathologic report catalogued as an appendiceal specimen was reviewed for a time period of 5 years (2013–2017) at our institution. Demographic, clinical, pathological and oncologic follow-up data were recorded. A descriptive study of the sample was completed. A total of 1434 appendiceal specimens was analyzed. Appendiceal neoplasms incidence was 3.2%. Epithelial tumors were the predominant histological subtype, making up 68% of the cases. Low-grade appendiceal mucinous neoplasia and neuroendocrine tumors were the most frequent neoplasms with malignant potential, with 13 and 6 cases, respectively. In more than 80% of neoplasia cases, the definitive treatment was appendectomy. Mortality cases were related to tumors with a very poor prognosis and an advanced stage. All patients had adequate oncological follow-up. Although it is still quite rare, the incidence of appendiceal tumors is increasing with an epidemiological change in favor of mucinous neoplasms currently predominating. Therefore, it is necessary to know and use an updated anatomo-pathological classification in order to provide correct treatment in the first or second surgical stage, as well as the correct follow-up of patients.

THU094 Multiple Endocrine Neoplasia Type 1 Tumor Recurrence After Loss To Follow Up

Abstract Disclosure: S.J. Sternlieb: None. K.G. Romo: None. R.S. Boothe: None. D. Englert: None. N. Manuel: None. Q.Z. Iqbal: None. Multiple Endocrine Neoplasia Type 1 Tumor Recurrence After Loss to Follow-up Sternlieb, S. J., Romo, K.G., Boothe, R., Manuel, N., Iqbal, Q.Z., Grissett, B., Englert, D. Background: MEN1 is a rare, autosomal dominant tumor disorder due to mutations in the MEN1 tumor suppressor gene. It is characterized by parathyroid, enteropancreatic and pituitary tumors. We present a young woman with MEN1 with prolactinoma, primary hyperparathyroidism and multiple pancreatic neuroendocrine tumors. Clinical Case: A 30-year-old woman with MEN1 presented with complaints of abdominal pain and GI bleeding (GIB). She was diagnosed with a prolactinoma at age 14 after presenting for primary amenorrhea and galactorrhea. She didn’t tolerate medical therapy with bromocriptine or cabergoline and required transphenoidal resection. At age 19, she presented with hypoglycemia and was found to have multiple pancreatic neuroendocrine tumors (NET) as well as a left (L) adrenal gland tumor. She underwent distal pancreatectomy and L adrenalectomy. Ten tumors in the pancreas stained variably for insulin, glucagon, gastrin and VIP. Multiple cortical adenomas were found in the adrenal gland. Post-operatively she developed a spinal cord hematoma related to placement of an epidural catheter for pain control, which led to permanent paraplegia. At age 21, she was diagnosed with primary hyperparathyroidism. She underwent left parathyroidectomy, then was lost to follow-up for 9 years. EGD showed multiple superficial duodenal ulcers. MRI brain identified a right (R) cavernous sinus mass inseparable from the R pituitary. CT abdomen showed a pancreatic head mass. Given the concern for neuroendocrine etiology, she underwent an EUS showing a pancreatic mass and a liver mass. Pancreatic mass pathology confirmed low-grade NET with Ki67 proliferation rate <1%, positive synaptophysin and chromogranin staining. After multidisciplinary discussion, the consensus was to continue PPI and sucralfate for GI ulcers, start lanreotide, and obtain somatostatin receptor scintigraphy. Surgery was not recommended unless significant GIB occurred on maximal therapy. She was referred to follow-up with GI, endocrinology, and NSGY. Since discharge, she has presented several times to other hospitals for abdominal pain, but has not adhered to follow-up. Conclusions: This case of recurrent neuroendocrine and pituitary tumors despite prior resections demonstrates the consequences of prolonged loss to follow-up with MEN1. Without routine surveillance, recurrence is likely. This patient lives in a rural area with lack of access to nearby subspecialty care, which is a barrier. More resources are needed to support patients with social barriers and progressive endocrinopathies. Key words: MEN1, prolactinoma, gastrinoma, NET, health care barriers Presentation: Thursday, June 15, 2023

The maximal contrast-enhanced range of CT for differentiating the WHO pathological subtypes and risk subgroups of thymic epithelial tumors.

To explore the value of maximal contrast-enhanced (CEmax) range using contrast-enhanced CT (CECT) imaging in differentiating the pathological subtypes and risk subgroups of thymic epithelial tumors (TETs). The pre-treatment-CECT images of 319 TET patients from May 2012 to November 2021 were analyzed retrospectively. The CEmax was defined as the maximum difference between the CT value of the solid tumor on pre-contrast and contrast-enhanced images. The mean CEmax value was calculated at three different tumor levels. There was a significant difference in the CEmax among the eight main pathological subtypes [types A, AB, B1, B2, and B3 thymoma, thymic carcinoma (TC), low-grade neuroendocrine tumor (NET) and high-grade NET] (p < 0.001). Among the eight subtypes, the CEmax values of types A, AB, and low-risk NET were higher than those of the other subtypes (all p < 0.001), and there was no difference among types B1-B3 and high-risk NET (all p > 0.05). There was no difference for CEmax values between NET and TC (p = 0.491). For the risk subgroups, the CEmax of TC (including NET) was 35.35 ± 11.41 HU, which was lower than that of low-risk thymoma (A and AB) (57.73±21.24 HU) (P < 0.001) and was higher than that of high-risk thymoma (B1-B3) (27.37±8.27 HU) (P < 0.001). The CEmax cut-off values were 38.5 HU and 30.5 HU respectively (AUC: 0.829 and 0.712; accuracy, 72.4% and 67.7%). The tumor CEmax on CECT helps differentiate the pathological subtypes and risk subgroups of TETs. In this study, an improved simplified risk grouping method was proposed based on the traditional (2004 edition) simplified risk grouping method for TETs. If Type B1 thymoma is classified as high-risk, radiologists using this improved method may improve the accuracy in differentiating risk level of TETs compared with the traditional method.