McKenzie, Travis J.

Introduction Previous studies have demonstrated that C 11 choline positron emission tomography/computed tomography (Choline-PET/CT) can localize abnormal parathyroid glands in the reoperative setting. This study assesses a large volume of patients with primary hyperparathyroidism (1HPT) who underwent Choline-PET/CT to confirm its utility in the setting of negative or equivocal conventional imaging. Methods All patients who underwent Choline-PET/CT for evaluation of 1HPT from July 2017 to July 2024 at a single institution were reviewed. Inclusion criteria were patients who underwent parathyroidectomy and had lab testing to assess for cure (defined as >50% drop from baseline PTH and into normal range, or resolution of hypercalcemia at follow-up). Sensitivity, positive predictive value (PPV), false negative rate (FNR), and accuracy were compared to conventional imaging (neck ultrasound, parathyroid scan, and parathyroid four-dimensional CT (4D-CT)). Subgroup analysis was conducted comparing sensitivity of modalities among index operations and separately in reoperations. Results 84 patients were included for analysis. 61 failed to localize on at least one conventional modality, and 15 failed to localize on all conventional studies. 67 patients (80%) achieved cure, of which 53 were reoperations. Choline-PET/CT outperformed conventional modalities across sensitivity, PPV, FNR, and accuracy. Choline-PET/CT also outperformed conventional modalities when comparing sensitivity in both subgroups. Conclusion C 11 choline-PET/CT is a valuable imaging modality in the reoperative setting and demonstrates utility for index operations. It provides localization when other modalities fail and allows for a high surgical cure rate. Further investigation into its utility as a primary imaging modality is warranted.

Abstract Disclosure: R. El Mouallem: None. T. McKenzie: None. A.N. Lteif: None. Background- Pancreatic neuroendocrine tumors (PNETs) are rare, but their incidence is rising. Ethanol ablation is increasingly used in adult patients with insulinomas or small nonfunctional PNETs, particularly in patients who are ineligible for surgical resection. Ethanol ablation of a PNET has not been previously reported in the pediatric population. Clinical Case- A 12-year-old female with known multiple endocrine neoplasia type 1 (MEN1) and multifocal PNETs presented for evaluation of a 1.3 cm nonfunctional, Dotatate avid pancreatic uncinate lesion. A CT angiogram of the pancreas revealed an arterially enhancing 1.3 cm nodule, which measured 8 mm one year prior. There was no evidence of metastatic disease. Given the increasing size of the lesion and young age of the patient, operative intervention was pursued. Due to the depth of the lesion and its proximity to the pancreatic duct during operative pancreas ultrasonography, surgical enucleation was deemed non-feasible. During the procedure, 7 additional subcentimeter pancreatic lesions concerning for PNETs were identified in the pancreatic body, tail, head and neck-body junction. Ultrasound guided ethanol ablation of the primary lesion was performed. Follow-up imaging demonstrated a promising response. 7 months post ablation, a Dotatate PET CT scan showed persistent focal uptake in the region of the ablated nodule. However, by 9 months, MRI abdomen revealed a decrease in the size of the lesion, now measuring 6 mm, with stable Dotatate uptake. By 19 months post ethanol ablation, the previously hyper-enhancing lesion was no longer visible on MRI, demonstrating complete structural resolution. Conclusion- This case demonstrates that ethanol ablation is a promising treatment option for PNETs in the pediatric population. Given the complexities of surgical resection in children, particularly for deep or anatomically challenging lesions, ethanol ablation offers a potentially less morbid alternative with encouraging outcomes. Further research may establish this approach as a viable option for select pediatric patients. Presentation: Sunday, July 13, 2025

Abstract Disclosure: P. Hopmann: None. S. Lund: None. T. Foster: None. B. Dy: None. T. McKenzie: None. G. Johnson: None. R.A. Wermers: None. M. Lyden: None. Background: Previous studies have demonstrated that C11 choline positron emission tomography/computed tomography (Choline-PET/CT) can localize abnormal parathyroid glands in the re-operative setting. This study assesses a large volume of patients with primary hyperparathyroidism (1HPT) who underwent Choline-PET/CT to confirm its utility in the setting of negative or equivocal conventional imaging. Methods: All patients who underwent Choline-PET/CT for evaluation of 1HPT from July 2017 to July 2024 at a single institution were reviewed. Inclusion criteria were patients who underwent parathyroidectomy and had lab testing to assess for cure (defined as >50% drop from baseline PTH and into normal range, or resolution of hypercalcemia at follow-up). Sensitivity, positive predictive value (PPV), false negative rate (FNR), and accuracy were compared to conventional imaging (neck ultrasound, parathyroid scan, and parathyroid four-dimensional CT (4D-CT)). Subgroup analysis was conducted comparing sensitivity of modalities among index operations, and separately in re-operations. Results: 176 patients were identified. 85 underwent parathyroidectomy, 1 patient was excluded due to lacking data to evaluate for cure. Of 91 patients who did not undergo parathyroidectomy, 45 were non-localizing on all imaging, and 46 had positive Choline-PET/CT findings but opted against surgery due to mild disease or prohibitive re-operative risk. Of the included 84 parathyroidectomy patients, 61 failed to localize on at least one conventional modality, and 15 failed to localize on all conventional studies. 67 patients (80%) achieved cure, of whom 53 were re-operations (range of 1-4 prior operations, average 1.5). Choline-PET/CT outperformed conventional modalities across sensitivity, PPV, FNR, and accuracy. Among index operations, Choline-PET/CT had significantly higher sensitivity than conventional modalities (100% vs 27% for ultrasound, 30% for parathyroid scan, 29% for 4D-CT; p values ≤0.01). This was also true in re-operations (95% for Choline-PET/CT vs 13% for ultrasound, 30% for parathyroid scan, 32% for 4D-CT; p values <0.01). Conclusion: C11 choline-PET/CT is a valuable imaging modality in the re-operative setting and demonstrates utility for index operations. It provides localization when other modalities fail and allows for a high surgical cure rate. Further investigation into its utility as a primary imaging modality is warranted. Presentation: Monday, July 14, 2025

Abstract Context Patients with mild autonomous cortisol secretion (MACS) can develop adrenal insufficiency after unilateral adrenalectomy. Objective This work aimed to determine the prevalence, duration, and predictors of adrenal insufficiency, and compare postoperative basal cortisol and cosyntropin stimulation test (CST). Methods In this multicenter retrospective study of patients with MACS, adrenal insufficiency was diagnosed when postoperative basal cortisol was less than 10 µg/dL and/or CST < 18 µg/dL. The results were concordant when both tests met cutoffs. Biochemical (BSS) and clinical severity scores (CSS) were calculated. Results Among 281 patients with MACS (80% women), postoperative adrenal insufficiency was diagnosed in 153 (54.5%) patients. Adrenal insufficiency inversely correlated with age (odds ratio [OR] 0.67 per 10 years; 95% CI, 0.53-0.84). Low basal cortisol and CST were associated with younger age (OR 0.64 per 10 years for both) and higher BSS (OR 1.17 and 1.22, respectively). Basal cortisol and CST were discordant in 22% of patients, and the discordance rate was more common in patients with bilateral nodules (32% vs 19%; P < .001). The median time to adrenal insufficiency recovery was 3.9 months (IQR, 3-5.9 months), with longer duration associated with higher BSS and CSS: 3 months for mild, 4 to 5 months for moderate, and 12 to 14 months for severe BSS and CSS. Conclusion Approximately half of patients with MACS developed postoperative adrenal insufficiency, with 50% recovering by 3.9 months after surgery. BSS correlated with basal cortisol, CST, and duration of adrenal insufficiency. As discordant results were noted in 22%, performing both basal cortisol and CST postoperatively should be considered.

Abstract Malignant insulinomas are rare pancreatic neuroendocrine tumors characterized by excessive insulin secretion and a high propensity for metastasis, leading to challenging management. This study retrospectively analyzed 57 patients treated for malignant insulinoma at Mayo Clinic sites between 1992 and 2024, focusing on the efficacy of systemic therapies in improving hypoglycemic control and survival outcomes. The most commonly used therapies included somatostatin analogs (SSA), everolimus, capecitabine-temozolomide (CAPTEM), and peptide receptor radionuclide therapy (PRRT). PRRT demonstrated the highest efficacy in controlling hypoglycemia (93%), followed by CAPTEM (68%) and everolimus (62%). SSA, chemotherapy, and streptozocin were less effective, with hypoglycemic improvement seen in 37.5, 33.3, and 28.6% of patients, respectively. Overall survival (OS) was longest with SSA at 84.67 months, followed by CAPTEM at 81.67 months and everolimus at 74.07 months. PRRT demonstrated a median OS of 49.73 months. In contrast, chemotherapy and streptozocin-based therapies had significantly shorter OS times of 15.23 and 8.35 months, respectively. These findings highlight significant variability in systemic therapy efficacy for malignant insulinoma, with PRRT emerging as a promising treatment for refractory hypoglycemia and long survival. Cox regression analysis identified primary tumor resection and a history of benign insulinoma as associated with longer OS. Optimal sequencing of therapies remains unclear, and individualized treatment plans based on hypoglycemic burden and tumor characteristics are critical for improving survival and quality of life in these patients.

Background: Oncocytic adrenal neoplasms, defined by ≥90 % of oncocytic cells, are rare. The significance of oncocytic changes within an adrenal neoplasm remains unclear. Methods: A retrospective study of adults who underwent adrenalectomy at a large center identified pure oncocytic neoplasms on final pathology (1997-2022). Neoplasms were categorized based on Lin-Weiss-Bisceglia system as malignant, benign, or of uncertain malignant potential. Analysis was performed using Fisher exact, Kruskal-Wallis tests, and Kaplan-Meier analysis. Results: Among a total of 33 patients, 24% had benign, 36% malignant, and 39% neoplasm of uncertain malignant potential. None of the benign neoplasms recurred, while 50% of the malignant neoplasms recurred (median of 40 months). Two of 13 neoplasms initially thought to be of uncertain malignant potential recurred as distant metastatic adrenocortical carcinoma at 11 and 25 months, over a median follow-up duration of 31 months. Ki67% was available for 20 patients: median (IQR) Ki67% was 5 (1, 5) for benign, 10 (6, 15) for malignant, and 6.5 (5, 10) for neoplasms of uncertain behavior, P = 0.05. Recurred neoplasms had higher Ki67% at initial resection compared to cases that did not recur. Conclusion: While oncocytic adrenal neoplasms are rare, a significant proportion are malignant or have malignant potential. Judicious follow-up is required for oncocytic adrenal neoplasms of uncertain malignant potential, as they can recur as metastatic adrenocortical carcinoma. Ki67% should always be obtained in cases of malignancy or uncertain malignant potential as it can predict recurrence. Larger studies are needed to evaluate the appropriate follow-up protocols for these neoplasms.

Abstract Disclosure: O. Hamidi: Advisory Board Member; Self; Corcept, Neurocrine Biosciences, Amryt Pharma, Recordati Rare Diseases, Lantheus, Xeris. B.H. Salama: None. P. Dogra: None. A.P. Dackiw: None. F. Nwariaku: None. A. Islam: None. A. Mehta: None. S.C. Oltmann: None. S. Mirfakhraee: None. T. McKenzie: None. T.R. Foster: None. M. Lyden: None. B.M. Dy: None. I. Bancos: None. Introduction: Patients with mild autonomous cortisol secretion (MACS) are at risk for adrenal insufficiency (AI) after unilateral adrenalectomy. We aimed to determine the prevalence, predictors, and duration of AI after unilateral adrenalectomy for MACS, and to compare baseline and peak cortisol post cosyntropin stimulation test (CST) in diagnosing AI. Methods: We conducted a dual-center retrospective cohort study of patients with MACS who underwent unilateral adrenalectomy and were evaluated with postoperative cosyntropin stimulation test (CST). AI was diagnosed when postoperative morning cortisol was <10μg/dL and/or CST peak cortisol was <18μg/dL. Baseline and CST peak cortisol levels were considered concordant when both met corresponding cut-offs. Biochemical (BSS) and clinical (CSS) severity scores for hypercortisolism were calculated. Results: In 100 adults with MACS (77% women, median age 56 years, interquartile range [IQR] 48-63), median adenoma size was 2.8 cm (IQR, 2.2-3.7), and 25 (25%) had bilateral nodules. Median BSS was 3 (IQR, 2-5) and median CSS was 4 (IQR, 2-8). After adrenalectomy, AI was diagnosed in 56 (56%) patients. AI was associated with higher BSS, larger tumor size, but not age, sex, BMI, tumor laterality. Baseline and CST peak cortisol levels were concordant in 76% of cases. In 14% of cases morning cortisol was <10μg/dL but CST peak cortisol was ≥18μg/dL, and in 10% of cases morning cortisol was ≥10μg/dL, but CST peak cortisol was <18μg/dL. On a multivariable analysis that included age, sex, BMI, BSS, laterality, and tumor size, only higher BSS (odd ratio [OR] = 1.6 per 1 point) was associated with postoperative baseline cortisol <10μg/dL (P<0.05 for all). Independent predictors of CST peak cortisol <18μg/dL were BSS (OR 1.5 per 1 point) and unilateral adenoma (OR 3.7). During a median postoperative follow up of 13 months, 33 (59%) patients recovered from AI. Median time to recovery was 6.0 months, with AI recovery in 28% of patients by 2 months, 42% by 3 months, 53% by 6 months, and 64% by 12 months. Conclusions: Prevalence of postoperative AI in MACS was 56%. Only 76% of patients had concordant baseline and CST peak cortisol, with peak CST cortisol being more commonly abnormal in patients treated for unilateral MACS. Patients with larger adenomas and higher BSS were at higher risk for AI. Patients with MACS should be counseled about the risk and duration of AI after adrenalectomy. Presentation: 6/3/2024

Abstract Disclosure: B. Bahrani Fard: None. N. Nikravangolsefid: None. J. Maroun: None. A. Cross: None. T. Foster: None. T. McKenzie: None. W. Young Jr: None. B.M. Dy: None. M. Lyden: None. I. Bancos: None. Background: Giant pheochromocytomas (PHEO), defined based on size > 10 cm, are rare. Data on clinical presentation, management, and prognosis of giant PHEOs are scarce. Objectives: to determine prevalence of giant PHEO and compare presentation, management, and outcomes of patients with giant vs non-giant PHEOs. Methods: We conducted a single-center retrospective cohort study of consecutive patients with giant PHEO and randomly chosen patients with non-giant PHEO (referents) at 6:1 ratio, evaluated between 2000-2023. All variables were extracted from the electronic medical record. Results: Of 828 patients with PHEO evaluated between 2000 and 2023, 31 (3.7%) had giant PHEO (median size 12 cm, IQR 10.0-13.5). In comparison to referents (n=186, median size 4 cm, IQR, 2.9-5.0), patients with giant PHEO were similar in age (median age 53 vs 55 years, P=.55), more frequently discovered based on symptoms (52% vs 32%, P=.04), and less likely to be bilateral (3% vs 12%, P=.31). Genetic testing was performed in 103 (48%) of patients, without group differences, however, patients with giant PHEO were less likely to have an associated germline mutation detected (7% vs 47%, P=.004). Patients with giant PHEO had more symptoms of catecholamine excess (median of 2 vs 1, P=.04) and presented with a higher prevalence of severe metanephrine excess >10 times above upper normal range (76% vs 30%, P<.0001). Adrenalectomy was performed in 94% of patients with giant PHEOs and in 100% referents, with higher rates of open adrenalectomy in giant PHEO (86% vs 14%, P<.0001). In addition to preoperative alpha-adrenergic blockade (89%), metyrosine was used in 14 (7%) patients, mostly in patients with giant PHEO (26% vs 3%, P<.0001). Patients with giant PHEO had a longer hospital length of stay (laparoscopic: median 5 vs 2 days, P<.0001; open: median 6 vs 5 days, P=.24), and a higher complication rate (31% vs 10%, P=.006).Median follow up was 3 years (IQR 1-8) years, similar in patients and referents. Metastases developed at a much higher rate in patients with giant PHEOs (45% vs 4% in referents, P<.0001). Disease specific mortality was 7% in patients with giant PHEOs and 0% in referents. Conclusion: Patients with giant PHEO were more symptomatic, had a higher degree of catecholamine excess, and a higher rate of perioperative complications. Almost half of patients with giant PHEO developed metastases, warranting a close follow-up. Presentation: 6/2/2024

Abstract Context Guidelines suggest performing urine steroid profiling in patients with indeterminate adrenal tumors to make a noninvasive diagnosis of adrenocortical carcinoma (ACC). However, urine steroid profiling is not widely available. Objective To determine the accuracy of clinically available serum 11-deoxycortisol, 17OH-progesterone, and 17OH-pregnenolone in diagnosing ACC. Methods We conducted a prospective single-center cohort study of patients with adrenal masses evaluated between 2015 and 2023. Serum was analyzed by liquid chromatography–mass spectrometry for 17OH-pregnenolone, 17OH-progesterone, and 11-deoxycortisol. Reference standard for adrenal mass included histopathology, imaging characteristics, imaging follow up of 2 years, or clinical follow up of 5 years. Localized Generalized Matrix Learning Vector Quantization analysis was used to develop serum steroid score and assessed with area under receiver operating curve. Results Of 263 patients with adrenal masses, 44 (16.7%) were diagnosed with ACC, 161 (61%) with adrenocortical adenomas (ACAs), 27 (10%) with other adrenal malignancies, and 31 (12%) with other. Hounsfield unit ≥ 20 was demonstrated in all ACCs, in all but 1 other adrenal malignancy, and in 58 (31%) ACAs. All 3 steroids were higher in patients with ACCs vs non-ACCs, including when comparing ACCs with functioning ACAs, and with ACAs with Hounsfield unit ≥ 20 (P < .0001 for all). Localized Generalized Matrix Learning Vector Quantization analysis yielded a serum steroid score that discriminated between ACC and non-ACC groups with a mean threshold fixed area under receiver operating curve of 0.823. Conclusion We showed that measurements of 11-deoxycortisol, 17OH-progesterone, and 17OH-pregnenolone could be valuable in diagnosing ACC. After appropriate validation, serum steroid score could be integrated in clinical practice.

Abstract Context Data on giant pheochromocytomas (PHEOs), defined based on size 10 cm or greater, are scarce. Objective This work aimed to compare presentation, management, and outcomes of patients with giant vs non–giant PHEOs. Methods A retrospective cohort study was conducted in a referral center from 2000 to 2023. Consecutive patients with giant PHEOs and randomly chosen patients with non–giant PHEO (referents) were studied at a 1:6 ratio. Outcomes included perioperative complications, metastases, and mortality. Results Of 828 patients with PHEOs, 31 (3.7%) had giant PHEO (median size 12 cm, interquartile range [IQR] 10.0-13.5 cm). In comparison to referents (n = 186, median size 4 cm, IQR, 2.9-5.0 cm), patients with giant PHEO had more symptoms of catecholamine excess (median of 2 vs 1; P = .04) and presented with a higher prevalence of severe catecholamine excess (76% vs 30%; P < .0001). Adrenalectomy was performed in 94% of patients with giant PHEOs and 100% of referents. In addition to preoperative α-adrenergic blockade (89%), metyrosine was used in 14 (7%) patients, mostly in patients with giant PHEOs (26% vs 3%; P < .0001). Patients with giant PHEOs had a higher perioperative complication rate (31% vs 10%; P = .004). During a median follow-up of 3 years, metastases developed at a higher rate in patients with giant PHEOs (45% vs 4% in referents; P < .0001). Disease-specific mortality was 7% in patients with giant PHEOs and 0% in referents (P = .02). Conclusion Patients with giant PHEOs compared to referents were more symptomatic, had a higher degree of catecholamine excess, and had a higher rate of perioperative complications. Almost half of patients with giant PHEOs developed metastases, warranting close follow-up.