Von Hippel-Lindau Research Articles

Comparative analysis of stereotactic radiosurgery outcomes for supratentorial hemangioblastomas in von hippel-lindau disease and sporadic cases: A multi-center international study

BackgroundHemangioblastomas (HBs) are rare, benign central nervous system (CNS) neoplasms that rarely occur in the supratentorial. Resection with the goal of gross total resection (GTR) is often considered the primary treatment. Stereotactic radiosurgery (SRS) has been utilized more commonly in unresectable or partially resected cases. In this study, we aimed to evaluate SRS’s effectiveness and clinical outcomes in supratentorial HBs. MethodsA retrospective analysis of multi-centers from 1993 to 2022 was conducted on patients with supratentorial HB treated with SRS. ResultsThe study included 13 patients with 30 supratentorial HBs (24 von Hippel-Lindau (VHL), 6 sporadic). Median age was 26 years. Most tumors were solid (86.2 %). SRS was primary treatment in 86.7 % of cases and adjuvant in 13.3 %. VHL lesions were significantly smaller than sporadic ones (0.2 vs. 3.7 cc, p = 0.009). Median margin dose was higher in VHL cases (17 vs. 13.0 Gy, P = 0.031). For VHL cases, local control (LC) was 100 % at 6 months, 96 % (95 % CI: 88 %, 100 %) from 12 to 60 months post-SRS. For sporadic cases, LC was 100 % at 6 months, 80 % (95 % CI: 52 %, 100 %) from 12 to 60 months post-SRS (p = 0.39). No adverse radiation events or mortality occurred. ConclusionSRS demonstrated a promising role in the clinical course of supratentorial HBs. It can be considered an effective alternative to surgical resection and even a first-line therapeutic option in appropriately selected cases.

Glucose deprivation impairs hypoxia-inducible factor-1α synthesis

Hypoxia-inducible factors (HIFs) are key transcriptional mediators of the hypoxic response and are implicated in oncogenesis. HIFα is regulated by a well-characterized, oxygen-dependent degradation pathway involving the von Hippel Lindau (VHL) tumor suppressor protein. However, comparatively little is known about HIFα regulation at the translational level, particularly under cellular stress. There is evidence that HIFα expression not only responds to changes in oxygen tension, but also nutrient availability. In this study, we monitored global translation rates, ATP levels and HIF1α synthesis rates in response to glucose starvation or glycolysis inhibition. We found that both global and HIF1α-specific translation rates decline under glucose deprivation that is concomitant with ATP reduction. These results are in contrast with previous reports showing preferential HIF1α synthesis despite global translation suppression under hypoxia and suggest that a glucose requirement in cellular metabolism is associated with HIF1α translation.

Design of Murine Double Minute 2 Proteolysis Targeting Chimera Degraders with a Built-In Tumor-Targeting Ability.

Proteolysis targeting chimeras (PROTACs) are heterobifunctional molecules to induce the proteasomal degradation of target proteins. Currently, there are no tumor-targeting PROTACs for modulating oncogenic murine double minute 2 (MDM2). AS1411 is a tumor-targeting aptamer that specifically recognizes nucleolin (NCL) overexpressed on the surface of tumor cells. We recently repurposed AS1411 as an MDM2 recruiter since it could form an NCL-bridged ternary complex with MDM2. In this study, we design a PROTAC molecule AS1411-VH032 via conjugating AS1411 with a recruiter of von Hippel-Lindau (VHL) ligase VH032. AS1411-VH032 facilitates tumor-selective degradation of MDM2, leading to tumor shrinkage with no detectable toxicity. Besides being a molecular target, MDM2 also serves as an E3 ligase harnessed by PROTACs. Thus, we developed an AS1411-based homo-PROTAC homoAS1411, which induces tumor-specific suicide degradation of MDM2 and prevents tumor progression without causing side effects. Both AS1411-VH032 and homoAS1411 are promising MDM2 degraders with built-in tumor-targeting ability, which balances the antitumor efficacy with a favorable safety profile.

Pheochromocytoma-Paraganglioma Syndrome: A Multiform Disease with Different Genotype and Phenotype Features.

Pheochromocytoma and paraganglioma (PPGL) are rare tumors derived from the adrenal medulla and extra-adrenal chromaffin cells. Diagnosis is often challenging due to the great variability in clinical presentation; the complexity of management due to the dangerous effects of catecholamine excess and the potentially malignant behavior require in-depth knowledge of the pathology and multidisciplinary management. Nowadays, diagnostic ability has certainly improved and guidelines and consensus documents for treatment and follow-up are available. A major impulse to the development of this knowledge has come from the new findings on the genetic and molecular characteristics of PPGLs. Germline mutation in susceptibility genes is detected in 40% of subjects, with a mutation frequency of 10-12% also in patients with sporadic presentation and genetic testing should be incorporated within clinical care. PPGL susceptibility genes include "old genes" associated with Neurofibromatosis type 1 (NF1 gene), Von Hippel Lindau syndrome (VHL gene) and Multiple Endocrine Neoplasia type 2 syndrome (RET gene), the family of SDHx genes (SDHA, SDHB, SDHC, SDHD, SDHAF2), and genes less frequently involved such as TMEM, MAX, and FH. Each gene has a different risk of relapse, malignancy, and other organ involvement; for mutation carriers, affected or asymptomatic, it is possible to define a tailored long-life surveillance program according to the gene involved. In addition, molecular characterization of the tumor has allowed the identification of somatic mutations in other driver genes, bringing to 70% the PPGLs for which we know the mechanisms of tumorigenesis. This has expanded the catalog of tumor driver genes, which are identifiable in up to 70% of patients Integrated genomic and transcriptomic data over the last 10 years have revealed three distinct major molecular signatures, triggered by pathogenic variants in susceptibility genes and characterized by the activation of a specific oncogenic signaling: the pseudo hypoxic, the kinase, and the Wnt signaling pathways. These molecular clusters show a different biochemical phenotype and clinical behavior; they may also represent the prerequisite for implementing customized therapy and follow-up.

Pediatric patients with von Hippel-Lindau and hemangioblastomas treated successfully with belzutifan.

Hemangioblastoma is the most common tumor associated with von Hippel-Lindau (VHL), and are a leading cause of mortality. We present five pediatric patients with VHL-associated hemangioblastomas treated with belzutifan, a hypoxia-inducible factor 2a (HIF2a) inhibitor. Three patients were started on belzutifan due to vision loss from progressive retinal hemangioblastomas. Within oneyear of treatment, all three patients had improvement in hemangioblastoma size and visual acuity. For patients with intracranial lesions, belzutifan resulted in an improvement in neurologic symptoms and hemangioblastoma size. Four patients experienced grade 1-2 anemia and two patients required a dose reduction. Our report suggests that belzutifan can be an effective therapy for pediatric, adolescent, and young adult patients with VHL-associated hemangioblastomas.

A Frozen Tale of Two Tumors in the Pancreas: An Intraoperative Diagnostic Challenge of Clear Cell Pancreatic Neuroendocrine Tumor Mimicking Metastatic Clear Cell Renal Cell Carcinoma

Abstract Introduction/Objective Clear cell pancreatic neuroendocrine tumor (PanNET) is rare, with very few cases reported in the literature, and is often found in patients with von Hippel-Lindau (VHL) disease. The differential for this entity includes ectopic adrenal tissue and metastatic clear cell neoplasms. These challenges during intraoperative consultation add to the complexity of diagnosing this condition. Distinguishing it from other pancreatic lesions requires careful examination and further ancillary testing. Methods/Case Report We report a case of clear cell PanNET mimicking metastatic clear cell renal cell carcinoma (RCC) in a 56-year-old woman with recently diagnosed VHL. She presented with renal masses and a pancreatic lesion with previous biopsy showing conventional NET. Intraoperative consultation during her pancreaticoduodenectomy identified a 1.3 cm well-circumscribed, golden-yellow solid mass. Further characterization was deferred to permanent sections given the diagnostic challenge of distinguishing between a PanNET and metastatic clear cell RCC. Permanent sections showed nests of clear cells with prominent nucleoli. The neoplastic cells were immunohistochemically positive for neuroendocrine markers synaptophysin, chromogranin and insulinoma- associated protein 1(INSM1), as well as pankeratin and PAX8, with a Ki-67% proliferation index <1%, consistent with low-grade clear cell PanNET. Clear cell RCC marker, CA-IX, as well as adrenocortical marker SF1, were negative. The combination of immunohistochemical stains is key for making the diagnosis. The previously biopsied conventional PanNET was also identified, which was positive for neuroendocrine markers and had a Ki-67 proliferation index <1%. Results (if a Case Study enter NA) NA Conclusion Given the rarity of this entity and its strong association with VHL, clear cell PanNET should be considered in the intraoperative consultation to inform clinical management. Furthermore, literature review indicates that metastatic RCC in the pancreas is exceptionally rare in VHL patients and typically of low nuclear grade, suggesting low metastatic potential. Thus, this case emphasizes the diagnostic challenges and the necessity of deferring to permanent sections with immunohistochemical work-up during intraoperative consultation or when assessing small biopsies.

USP7 depletion potentiates HIF2α degradation and inhibits clear cell renal cell carcinoma progression

Clear cell renal cell carcinoma (ccRCC) is characterized by Von Hippel Lindau (VHL) gene loss of function mutation, which leads to the accumulation of hypoxia-inducible factor 2α (HIF2α). HIF2α has been well-established as one of the major oncogenic drivers of ccRCC, however, its therapeutic targeting remains a challenge. Through an analysis of proteomic data from ccRCCs and adjacent non-tumor tissues, we herein revealed that Ubiquitin-Specific Peptidase 7 (USP7) was upregulated in tumor tissues, and its depletion by inhibitors or shRNAs caused significant suppression of tumor progression in vitro and in vivo. Mechanistically, USP7 expression is activated by the transcription factors FUBP1 and FUBP3, and it promotes tumor progression mainly by deubiquitinating and stabilizing HIF2α. Moreover, the combination of USP7 inhibitors and afatinib (an ERBB family inhibitor) coordinately induce cell death and tumor suppression. In mechanism, afatinib indirectly inhibits USP7 transcription and accelerates the degradation of HIF2α protein, and the combination of them caused a more profound suppression of HIF2α abundance. These findings reveal a FUBPs-USP7-HIF2α regulatory axis that underlies the progression of ccRCC and provides a rationale for therapeutic targeting of oncogenic HIF2α via combinational treatment of USP7 inhibitor and afatinib.

Carbonic Anhydrase IX (CA9) Overexpression and Negative PAX8 Staining Can Be Used to Confirm Hemangioblastomas

Abstract Introduction/Objective Hemangioblastomas are indolent brain tumors consisting histologically of atypical stromal cells and a large number of blood vessels lined by endothelial cells. The tumors are often associated with either von Hippel- Lindau (VHL) syndrome or sporadic mutation of VHL genes. As CA9 is a marker of the hypoxic inducible factor-alpha1 cascade, its overexpression has been well known to present in clear cell renal cell carcinoma that involves the mutation of VHL gene. A few studies demonstrate overexpression of CA9 in hemangioblastomas, but not in other primary brain tumors such as gliomas and meningioma. Our two cases were used to determine if positive CA9 and negative PAX8 immuno-stains were useful markers to support the diagnosis of hemangioblastomas. Methods/Case Report One patient was a 50-year-old man and the other patient was a 75-year-old man. Two lesions were identified in the cerebellum with typical appearance of vascular channels intermingled with atypical stromal cells showing clear cell cytoplasm. The endothelial cells were positive for CD34 and ERG. The stromal cells were weakly positive for inhibin but negative for the endothelial markers GFAP, pancytokeratin and PAX8, ruling out primary glioma and metastatic clear cell renal carcinoma. The atypical stromal cells with clear cytoplasm in both tumors, however, showed strong and diffuse membranous staining for CA9 (3+). The overall findings supported the morphologic diagnosis of hemangioblastomas in both patients. Results (if a Case Study enter NA) NA Conclusion Our preliminary data indicates that positive CA9 and negative PAX8 stains are a useful pair of markers to support a diagnosis of hemangioblastoma and differentiate them from metastatic clear cell renal cell carcinoma. Additionally, CA9 can help confirm the diagnosis of hemangioblastoma when inhibin is weak or nearly negative.

Somatostatin receptor 2A expression in von Hippel-Lindau-related hemangioblastomas.

Central nervous system hemangioblastomas are the most prevalent manifestation of von Hippel-Lindau (VHL) disease and remain the main cause of mortality. Surgical resection is the primary treatment strategy, but is not always possible, and should be used as restrictively as possible. There is an unmet need for less invasive treatment strategies, such as targeted therapy. Expression of somatostatin receptor 2A (SSTR2A) in VHL-related hemangioblastomas has been described earlier, but the extent of expression in a larger population has yet to be determined. The authors hypothesize that a substantial subset of VHL-related hemangioblastomas show SSTR2A expression, which may serve as a potential new treatment target. Patients who were surgically treated for a VHL-related hemangioblastoma from 1990 until 2021 at the UMC Utrecht were included. Clinical data was derived from a clinical database. Tissue samples were histopathologically examined with use of hematoxylin and eosin staining, and immunohistochemical analysis of SSTR2A expression was performed. Forty-three tissue samples were obtained from 26 patients. Nine showed strong positivity for SSTR2A expression, whereas 13 showed moderate and 15 sparse expression. Three samples showed no expression of SSTR2A. The distribution showed right-skewedness favoring a strong expression. SSTR2A expression colocalized with endothelial markers and not with stromal cells. Additionally, within-patient variability for SSTR2A expression was described in 14 patients. SSTR2A is expressed in varying degrees in the majority of VHL-related hemangioblastomas. Future treatment with somatostatin analogues or even peptide receptor radionuclide treatment may be considered for SSTR2A-positive cases.

Emerging innovative treatment strategies for advanced clear cell renal cell carcinoma.

Dramatic advances in biological discoveries, since the 1990s, have continued to reshape the treatment paradigm of metastatic renal cell carcinoma (RCC). Von Hippel Lindau (VHL) gene alterations are associated with pro-angiogenic activity and are central to the pathogenesis of clear cell RCC (ccRCC), the most predominant histologic subtype of RCC. Antiangiogenic strategies revolving around this VHL/HIF/VEGF axis have been shown to improve survival in metastatic ccRCC. The discovery of immune checkpoints and agents that target their inhibition introduced a new treatment paradigm for patients with RCC. While initially approved as monotherapy, studies investigating immune checkpoint inhibitor combinations have led to their approval as the new standard of care, providing durable responses and unprecedented improvements in clinical outcome. Despite these advances, the projected 14390 deaths in 2024 from RCC underscore the need to continue efforts in expanding and optimizing treatment options for patients with metastatic RCC. This article reviews key findings that have transformed the way we understand and treat metastatic RCC, in addition to highlighting novel treatment strategies that are currently under development.

G‐Quadruplex RNA Based PROTAC Enables Targeted Degradation of RNA Binding Protein FMRP for Tumor Immunotherapy

AbstractFragile X mental retardation protein (FMRP), an RNA binding protein (RBP), is aberrantly hyper‐expressed in human tumors and plays an essential role in tumor invasion, metastasis and immune evasion. However, there is no small‐molecule inhibitor for FMRP so far. In this study, we developed the first FMRP‐targeting degrader based on PROteolysis TArgeting Chimera (PROTAC) technology and constructed a heterobifunctional PROTAC through linking a FMRP‐targeting G‐quadruplex RNA (sc1) to a von Hippel‐Lindau (VHL)‐targeting ligand peptide (named as sc1‐VHLL). Sc1‐VHLL specifically degraded endogenous FMRP via ubiquitination pathway in both mouse and human cancer cells. The FMRP degradation significantly changed the secretion pattern of cancer cells, resulting in higher expression of pro‐inflammatory cytokine and smaller amounts of immunomodulatory contents. Furthermore, sc1‐VHLL, when encapsulated into ionizable liposome nanoparticles (LNP), efficiently targeted tumor site and degraded FMRP in cancer cells. In CT26 tumor‐bearing mouse model, FMRP degradation within tumors substantially promoted the infiltration of lymphocytes and CD8 T cells and reduced the proportion of Treg cells, reshaping the proinflammatory tumor microenvironment and accordingly transforming cold tumor into hot tumor. When combined with immune checkpoint blockade (ICB) therapy, sc1‐VHLL based treatment remarkably inhibited the tumor growth.

G-Quadruplex RNA Based PROTAC Enables Targeted Degradation of RNA Binding Protein FMRP for Tumor Immunotherapy.

Fragile X mental retardation protein (FMRP), an RNA binding protein (RBP), is aberrantly hyper-expressed in human tumors and plays an essential role in tumor invasion, metastasis and immune evasion. However, there is no small-molecule inhibitor for FMRP so far. In this study, we developed the first FMRP-targeting degrader based on PROteolysis TArgeting Chimera (PROTAC) technology and constructed a heterobifunctional PROTAC through linking a FMRP-targeting G-quadruplex RNA (sc1) to a von Hippel-Lindau (VHL)-targeting ligand peptide (named as sc1-VHLL). Sc1-VHLL specifically degraded endogenous FMRP via ubiquitination pathway in both mouse and human cancer cells. The FMRP degradation significantly changed the secretion pattern of cancer cells, resulting in higher expression of pro-inflammatory cytokine and smaller amounts of immunomodulatory contents. Furthermore, sc1-VHLL, when encapsulated into ionizable liposome nanoparticles (LNP), efficiently targeted tumor site and degraded FMRP in cancer cells. In CT26 tumor-bearing mouse model, FMRP degradation within tumors substantially promoted the infiltration of lymphocytes and CD8 T cells and reduced the proportion of Treg cells, reshaping the proinflammatory tumor microenvironment and accordingly transforming cold tumor into hot tumor. When combined with immune checkpoint blockade (ICB) therapy, sc1-VHLL based treatment remarkably inhibited the tumor growth.

The Interplay between von Hippel-Lindau Tumor Suppressor Gene, Lon Protease, ROS Accumulation, and Inflammation in Clear Cell Renal Cell Carcinoma.

This study explores the role of the von Hippel-Lindau (VHL) tumor suppressor gene and Lon protease in the development of clear cell renal carcinoma (ccRCC) through mechanisms involving inflammation and reactive oxygen species (ROS) accumulation in kidney cells. By examining the impact of VHL on the early stages of kidney cancer development, this research highlights the contributions of inflammation and ROS, as well as the involvement of Lon protease. The findings reveal increased Lon expression and ROS levels in VHL-knockdown HK-2 cells, along with elevated phospho-c-Jun N-terminal kinase (JNK) levels, emphasizing the complex interplay between VHL, Lon protease, inflammation, and ROS in kidney cell models. These insights point to potential therapeutic pathways for ccRCC.

Genotype-phenotype correlation of ocular von Hippel-Lindau disease in Koreans.

This scientific report aims to investigate the genotype-phenotype correlations of retinal hemangioblastoma (RH) in von Hippel-Lindau (VHL) disease. The study included 77 patients with genetically confirmed VHL disease who visited an ophthalmology clinic for the evaluation of RH. The presence, location, and size of RH were evaluated, Patients were categorized into three groups based on variants: HIF-1α binding site missense (HM), non-HIF-1α binding site missense (nHM), and truncating (TR) mutations. Fifty-six patients (72.7%) had RH in either eye, and 24 had bilateral RH. Sixteen patients (20.8%) had juxtapapillary RH in either eye. Nine patients had RH ≥ 2.0 disc diameters in size. VHL c.208G>A variant was the most frequent single mutation. Compared with patients having nHM mutations (15 patients) in VHL gene, patients with HM mutations (33 patients) or TR mutations (26 patients) presented a greater number of eyes affected (p = 0.007 and 0.004, respectively), a greater number of RH (p = 0.012 and 0.003, respectively), and more frequent presentation of large RH ≥ 2.0 disc diameters (p = 0.012, and 0.013, respectively). In conclusion, this study provides a deeper understanding of the genetic spectrum of VHL disease in Korean VHL disease and highlights the importance of the location of missense mutations regarding the risk of RH.

8789 Unraveling Von Hippel Lindau Syndrome: A Comprehensive Analysis of Clinical Manifestations, Age-Related Variations, and Tumor Prevalence in a Specialized Endocrine Center

Abstract Disclosure: K.K. Pasam: None. Y. Gupta: None. A. Goyal: None. N. Tandon: None. Introduction: This study presents a thorough examination of Von Hippel Lindau (VHL) syndromes, focusing on the clinical spectrum and genetic mutations in our population. Methods: The study, conducted at the Department of Endocrinology and Metabolism from 2016 to 2022. Objectives included studying the spectrum of diseases in index patients and asymptomatic family members. Results: In our study, we identified 19 index cases and 12 asymptomatic cases identified on screening. The analysis of 31 VHL patients revealed a mean age of presentation of 24.2±11.1 years. Pancreatic cysts were the most common manifestation in 61% followed by pheochromocytoma in 54%, cerebellar hemangioblastomas in 45%, retinal angiomas in 39% and renal cell carcinoma in 35%. 16% of patients presented with nonfunctioning pancreatic neuroendocrine tumors, and one case featured an endolymphatic sac tumor.Pheochromocytomas in VHL syndrome presented at a remarkably young age, with an average of 23.1±11.4 years. Bilateral pheochromocytomas were observed in 14 (82%) and hormonal evaluation revealed urinary noradrenaline, normetanephrines, and plasma normetanephrine elevations of 5, 6, and 7-fold, respectively.The median size of pheochromocytomas in VHL syndrome was 5.4 cm. Metastatic pheochromocytoma was observed in one patient. Genetic analysis was available for 9 patients with most common mutation in exon 3 of chromosome 3. Discussion:The average age of VHL syndrome presentation in our cohort is younger than in other Indian studies. Males in our study were 45%, deviating from the absence of gender preponderance associated with VHL. Disparities in age of diagnosis and tumor prevalence compared with other international cohorts highlight potential regional and ethnic variations. Multiple pancreatic cysts in our study, with a prevalence of 61%, lower than the South Indian study's 71%. Literature comparisons indicate pancreatic cyst prevalence ranging from 42% to 51.6%. Cerebellar hemangioblastomas and retinal angiomas, typical VHL lesions, displayed prevalence rates of 45% and 39%, respectively.Pheochromocytoma, the second most common tumor in our cohort (54%), exhibited variations in prevalence compared to international studies. Higher rates reported by Fagundes et al. and Dwivedi et al. from Brazil might be attributed to recruitment biases from endocrine centers.The average age of VHL-associated pheochromocytoma presentation in our study contrasts with MEN2, emphasizing the unique features of VHL. Our study, reporting a 16% prevalence of PNETs, aligns with Binderup et al. The mean age of presentation for VHL-associated PNETs (20.8 ± 3.63 years) contrasts with Western literature, suggesting potential ethnic differences. Conclusion: Our study contributes to a nuanced understanding of VHL syndrome, shedding light on age-related variations, gender distribution, and tumor prevalence. Presentation: 6/2/2024

8789 Unraveling Von Hippel Lindau Syndrome: A Comprehensive Analysis Of Clinical Manifestations, Age-Related Variations, And Tumor Prevalence In A Specialized Endocrine Center

Abstract Disclosure: K.K. Pasam: None. Y. Gupta: None. A. Goyal: None. N. Tandon: None. Introduction: This study presents a thorough examination of Von Hippel Lindau (VHL) syndromes, focusing on the clinical spectrum and genetic mutations in our population. Methods: The study, conducted at the Department of Endocrinology and Metabolism from 2016 to 2022. Objectives included studying the spectrum of diseases in index patients and asymptomatic family members. Results: In our study, we identified 19 index cases and 12 asymptomatic cases identified on screening. The analysis of 31 VHL patients revealed a mean age of presentation of 24.2±11.1 years. Pancreatic cysts were the most common manifestation in 61% followed by pheochromocytoma in 54%, cerebellar hemangioblastomas in 45%, retinal angiomas in 39% and renal cell carcinoma in 35%. 16% of patients presented with nonfunctioning pancreatic neuroendocrine tumors, and one case featured an endolymphatic sac tumor.Pheochromocytomas in VHL syndrome presented at a remarkably young age, with an average of 23.1±11.4 years. Bilateral pheochromocytomas were observed in 14 (82%) and hormonal evaluation revealed urinary noradrenaline, normetanephrines, and plasma normetanephrine elevations of 5, 6, and 7-fold, respectively.The median size of pheochromocytomas in VHL syndrome was 5.4 cm. Metastatic pheochromocytoma was observed in one patient. Genetic analysis was available for 9 patients with most common mutation in exon 3 of chromosome 3. Discussion:The average age of VHL syndrome presentation in our cohort is younger than in other Indian studies. Males in our study were 45%, deviating from the absence of gender preponderance associated with VHL. Disparities in age of diagnosis and tumor prevalence compared with other international cohorts highlight potential regional and ethnic variations. Multiple pancreatic cysts in our study, with a prevalence of 61%, lower than the South Indian study's 71%. Literature comparisons indicate pancreatic cyst prevalence ranging from 42% to 51.6%. Cerebellar hemangioblastomas and retinal angiomas, typical VHL lesions, displayed prevalence rates of 45% and 39%, respectively.Pheochromocytoma, the second most common tumor in our cohort (54%), exhibited variations in prevalence compared to international studies. Higher rates reported by Fagundes et al. and Dwivedi et al. from Brazil might be attributed to recruitment biases from endocrine centers.The average age of VHL-associated pheochromocytoma presentation in our study contrasts with MEN2, emphasizing the unique features of VHL. Our study, reporting a 16% prevalence of PNETs, aligns with Binderup et al. The mean age of presentation for VHL-associated PNETs (20.8 ± 3.63 years) contrasts with Western literature, suggesting potential ethnic differences. Conclusion: Our study contributes to a nuanced understanding of VHL syndrome, shedding light on age-related variations, gender distribution, and tumor prevalence. Presentation: 6/2/2024

8623 Atypical VHL Genetic Variant Causing Paraganglioma

Abstract Disclosure: G. Mangu: None. J.J. Faria Briceno: None. R. Yatavelli: None. Abstract: Pheochromocytomas and paragangliomas (PPGLs) are rare chromaffin cell tumors that originate from the adrenal medulla and extra-adrenal paraganglia respectively. Previous studies have shown that incidental PPGLs are seen in older patients with mild symptoms. They have lower levels of plasma catecholamines and lower incidence of malignancy than patients with nonincidental PPGLs. We report a case of an incidental paraganglioma in a young female with atypical pathogenic variant in the VHL gene which is known to cause familial erythrocytosis but NOT VHL syndrome or PPGL. Case Presentation: A 33-year-old African American female with no significant medical history presented to the emergency room with the chief complaint of right lower quadrant pain for 2 days, which started with her menstruation. The vitals were BP 128/67, pulse 67 and physical examination was unremarkable. CT showed a 4.0 x 3.0 cm heterogenous enhancing left adrenal mass and MRI with adrenal protocol revealed 3.4 x 3.1 cm mass consistent with pheochromocytoma. Labs revealed elevated plasma nor metanephrines and 24-hour urine normetanephrines were 1020 mcg. She was asymptomatic without hypertension, palpitations, or chest pain. She underwent laparoscopic left adrenalectomy after appropriate alpha blockade. The pathology report showed left periadrenal paraganglioma with immunohistochemistry staining significant for Carbonic anhydrase IX (CAIX) membranous expression which is mostly seen in paragangliomas associated with von Hippel-Lindau syndrome. Clinically, she did not have any stigmata for hereditary PPGL syndrome. Her genetic testing revealed a pathogenic heterozygous variant in the VHL gene, Exon 3, c.598C.T (pArg200Trp), which is a missense variant expected to disrupt VHL protein function. Although she has a germline mutation in VHL, it is not the garden variant which is associated with classic VHL syndrome. It has been reported to cause autosomal recessive erythrocytosis but not PPGL. Conclusion: The pathogenic heterozygous variant in VHL gene, Exon 3, c.598C.T (pArg200Trp) is known to cause autosomal recessive familial erythrocytosis type 2 in the Chuvash population, termed as Chuvash Polycythemia. Our patient did not have polycythemia but had iron deficiency anemia from menorrhagia. Several studies have reported that this variant does not cause VHL syndrome, however it has been reported in a single family with VHL syndrome but WITHOUT pheochromocytoma. To our knowledge, incidental adrenergic paraganglioma associated with this mutation has not been reported in the literature. Presentation: 6/3/2024

8338 A Case Series of 3 Patients with Unusual Miliary Lung Metastases in Paraganglioma: Diagnostic Workup, Treatment Challenges and Outcomes

Abstract Disclosure: K.M. Charles: None. M.A. Nazari: None. A. Jha: None. A. Derkyi: None. S. Talvacchio: None. M.J. Kuo: None. M. Patel: None. T. Prodanov: None. A.S. Alzahrani: None. A. Chen: None. J. Glod: None. J. Del Rivero: None. A.M. Gharib: None. K. Pacak: None. Background: Pheochromocytomas (PCCs) and paragangliomas (PGLs, together PPGLs) are uncommon neuroendocrine tumors originating from adrenal medulla chromaffin cells and sympathetic/parasympathetic ganglia. Metastatic disease occurs in a subset of PPGLs, ranging from 5% to 30% depending on the underlying genetic factors. Metastases are typically found in the bone, lung, lymph nodes, or liver. Historically, there have been no reported cases of PPGL with miliary pattern of pulmonary metastases. Methods: Three patients were identified with pulmonary metastases. All patients were evaluated between 2016 and 2023, and all developed extensive pulmonary metastatic disease. The evaluation process involved reviewing their medical history, laboratory results, and potential therapeutic approaches. Each patient underwent surgical intervention for the primary tumor and received systemic therapies once metastatic spread was detected. Results: We present three patients with either germline succinate dehydrogenase subunit D (SDHD) or von Hippel-Lindau (VHL) pathogenic variants who developed this rare condition. Patient 1: a 14-year-old female with right PCC and a recurrent left neck PGL carrying VHL type 2 pathogenic variant: VHL c.250G>T (p.Val84Leu) and received various chemotherapies with an unfavorable response. Patient 2: a 23-year-old female with a left jugular PGL carrying SDHD pathogenic variant: SDHD c.124_127delinsA TA (p.Glu42Ilefs*44). Patient 3: a 26-year-old female with a right PCC carrying a germline VHL type 2 pathogenic variant: VHL c.439C>G (p.Leu147Val). The latter two patients experienced disease stabilization through chemotherapy and systemic targeted radiotherapy, respectively.Discussion/Conclusion: This case series is unique as it highlights the rare occurrence of miliary spread of pulmonary metastases resulting from PCC or PGL. It also provides insight into prospective treatments options and outcomes for clinicians administering care within this population of patients. Though it is not clear at this time, this case series may represent a new subset of PPGL that have different genomic features and require a different therapeutic approach. Presentation: 6/1/2024

8338 A Case Series Of 3 Patients With Unusual Miliary Lung Metastases In Paraganglioma: Diagnostic Workup, Treatment Challenges And Outcomes

Abstract Disclosure: K.M. Charles: None. M.A. Nazari: None. A. Jha: None. A. Derkyi: None. S. Talvacchio: None. M.J. Kuo: None. M. Patel: None. T. Prodanov: None. A.S. Alzahrani: None. A. Chen: None. J. Glod: None. J. Del Rivero: None. A.M. Gharib: None. K. Pacak: None. Background: Pheochromocytomas (PCCs) and paragangliomas (PGLs, together PPGLs) are uncommon neuroendocrine tumors originating from adrenal medulla chromaffin cells and sympathetic/parasympathetic ganglia. Metastatic disease occurs in a subset of PPGLs, ranging from 5% to 30% depending on the underlying genetic factors. Metastases are typically found in the bone, lung, lymph nodes, or liver. Historically, there have been no reported cases of PPGL with miliary pattern of pulmonary metastases. Methods: Three patients were identified with pulmonary metastases. All patients were evaluated between 2016 and 2023, and all developed extensive pulmonary metastatic disease. The evaluation process involved reviewing their medical history, laboratory results, and potential therapeutic approaches. Each patient underwent surgical intervention for the primary tumor and received systemic therapies once metastatic spread was detected. Results: We present three patients with either germline succinate dehydrogenase subunit D (SDHD) or von Hippel-Lindau (VHL) pathogenic variants who developed this rare condition. Patient 1: a 14-year-old female with right PCC and a recurrent left neck PGL carrying VHL type 2 pathogenic variant: VHL c.250G>T (p.Val84Leu) and received various chemotherapies with an unfavorable response. Patient 2: a 23-year-old female with a left jugular PGL carrying SDHD pathogenic variant: SDHD c.124_127delinsA TA (p.Glu42Ilefs*44). Patient 3: a 26-year-old female with a right PCC carrying a germline VHL type 2 pathogenic variant: VHL c.439C>G (p.Leu147Val). The latter two patients experienced disease stabilization through chemotherapy and systemic targeted radiotherapy, respectively. Discussion/Conclusion: This case series is unique as it highlights the rare occurrence of miliary spread of pulmonary metastases resulting from PCC or PGL. It also provides insight into prospective treatments options and outcomes for clinicians administering care within this population of patients. Though it is not clear at this time, this case series may represent a new subset of PPGL that have different genomic features and require a different therapeutic approach. Presentation: 6/1/2024

6891 Exclusive Normetanephrine Secreting Pheochromocytoma In A Young Male

Abstract Disclosure: E. Askar: None. H. Moran: None. IntroductionPheochromocytomas and paragangliomas arise from chromaffin cells and produce excessive catecholamines. Hypertension is their primary clinical symptom. they differ in their catecholamine secretory phenotype; paragangliomas typically secrete norepinephrine, while pheochromocytomas typically secrete epinephrine. Here, we present a case 21-year-old male with pheochromocytoma with elevated norepinephrine but normal epinephrine levels.Case presentationA 21 -year-old male with no past medical history presented with episodes of palpitations, sweating, and elevated blood pressure. He also reported abdominal pain. On admission, his blood pressure was 143/92 mmHg, pulse was 71/min, respiration was 16/min, and oxygen saturation was 100% in room air. The rest of physical exam was not significant. His electrolyte panel was normal. Computed tomography (CT) abdomen and pelvis with contrast was performed and showed a right adrenal mass measuring 4.9 x 4.0 x 6.5 cm which is predominantly hypoattenuating (approximately 30 Hounsfield units) with thick nodular rim of enhancement. Hormonal workup showed normal serum testosterone, DHEA-S, AM cortisol, ACTH, aldosterone, plasma metanephrine, and urine metanephrine, but profoundly high plasma normetanephrine 3641.6 (0.0-210.1) pg/mL. His 24-hour urinary normetanephrine was elevated at 14874 (80-440) ug/24hr, confirming a pheochromocytoma. The high norepinephrine level in the setting of normal epinephrine raised suspicion for Von Hippel Lindau (VHL). He was started on alpha and beta blockage and had laparoscopic removal of the right adrenal gland. The pathology report confirmed the diagnosis of pheochromocytoma confined to right adrenal. The patient was then referred for genetic testing. Conclusion: Pheochromocytoma can be a part of familial disorders, although being sporadic in nature most of the time. As demonstrated in our case, the hallmark of pheochromocytoma associated with VHL is nearly exclusive normetanephrine secretion and a high ratio of normetanephrine to metanephrine. Confirmation and testing of genes aid in proper monitoring and follow-up. The preferred course of treatment is radical resection. Presentation: 6/2/2024