Oral HIF-2α Inhibitor Belzutifan in Ocular von Hippel-Lindau Disease: Subgroup Analysis of the Single-Arm Phase 2 LITESPARK-004 Study.

OBJECTIVE: To report the efficacy of oral HIF-2α inhibitor belzutifan in participants with von Hippel-Lindau disease-associated retinal hemangioblastomas in LITESPARK-004. DESIGN: Subgroup analysis of the phase 2, single-arm, open-label LITESPARK-004 study. PARTICIPANTS: Adults with ≥1 von Hippel-Lindau disease-associated measurable renal cell carcinoma tumor not requiring immediate surgical intervention were eligible. METHODS AND INTERVENTION: Participants received oral belzutifan 120 mg once daily until disease progression or unacceptable treatment-related toxicity. MAIN OUTCOME MEASURES: Efficacy of belzutifan in retinal hemangioblastomas was a secondary end point, measured as response (improved, stable, or progressed) by independent reading center certified graders based on color fundus imaging performed every 12 weeks using the investigator's preferred imaging standards. Additional assessments, where available, included optical coherence tomography and ultra-widefield fluorescein angiography. RESULTS: Among 61 participants in LITESPARK-004, 12 had ≥1 evaluable active retinal hemangioblastoma in 16 eyes at baseline per independent reading center. As of April 1, 2022, the median follow-up for participants with ocular von Hippel-Lindau disease at baseline was 37.3 months. All 16 eyes were graded as improved, with a response rate of 100.0% (95% confidence intervals, 79.4-100.0). No new retinal hemangioblastomas or ocular disease progression were reported as of data cutoff date. Eight participants had additional multimodal eye assessments performed at the National Institutes of Health study site. Among this subgroup, 10 of 24 hemangioblastomas in 8 eyes of 6 participants measured ≥500 µm in greatest linear dimension at baseline and were further analyzed. All 10 hemangioblastomas had a mean area reduction of ≥15% by month 12 and ≥30% by month 24. CONCLUSIONS: Belzutifan showed promising activity against ocular von Hippel-Lindau disease, including capacity to control retinal hemangioblastomas, with effects sustained for >2 years while on treatment.

Diagnostic Role of Oral Fluorescein Angiography in Pediatric Ambulatory Clinics.

Oral ingestion of fluorescein can be done in ambulatory pediatric clinics. We show that oral ultra-widefield fluorescein angiography is a non-invasive approach to rapidly diagnose and manage a diverse set of pediatric retinal vascular diseases.

Multimodal management of giant solid hemangioblastomas in two patients with preoperative embolization.

Background: Hemangioblastomas are benign vascular neoplasms, World Health Organization grade I, with the most frequent location in the cerebellum. Complete microsurgical resection can be a challenge due to excessive bleeding, which is why preoperative embolization takes importance. Case Description: Two clinical cases are presented, a 25-year-old woman and a 75-year-old man, who presented with intracranial hypertension symptoms due to obstructive hydrocephalus; a ventriculoperitoneal shunt was placed in both cases; in addition, they presented with cerebellar signs. Both underwent embolization with ethylene vinyl alcohol copolymer, with blood flow reduction. After that, they underwent microsurgical resection within the 1st-week post embolization, obtaining, in both cases, gross total resection without hemodynamic complications, with clinical improvement and good surgical outcome. It is worth mentioning that surgical management is the gold standard that allows a suitable surgical approach, like in our patients, for which a lateral suboccipital craniotomy was performed. Conclusion: Solid hemangioblastomas are less frequent than their cystic counterparts. The treatment is the surgical resection, which is a challenge and always has to be considered as an arteriovenous malformation in the surgical planning, including preoperative embolization to reduce perioperative morbidity and mortality and get good outcomes.

Case Report of a Hemangioblastoma Originating from the T1 Spinal Nerve Treated with in Toto Resection, Hemicorporectomy and Pedicle Screw Stabilization.

Introduction: Previously, only 40 cases with extradural hemangioblastoma at the spinal nerve (none at the T1 nerve root) have been described in the medical literature. In toto, resection of this hypervascular tumor is essential to avoid bleeding complications. Surgery for hemangioblastoma at the cervicothoracic junction is complex and nerve resection of the T1 results in specific neurodeficits of the hand muscles which are not well known. Case Report: A 34-year-old woman was diagnosed with a slowly growing tumor located at the left foramen T1/T2. Pressure from the tumor resulted in Horner's syndrome and pain and paresthesia in the upper extremity. The tumor was resected in toto through a posterior midline approach and rib resection and transection of the left T1 and T2 spinal nerves. T2 hemicorporectomy and spinal stabilization were performed to gain access to and mobilize the tumor ventrally. Ptosis decreased after surgery and no neurodeficit was observed except the expected deficit (no deficit was present preoperatively) caused by the T1 resection specifically a small decrease in strength of the abductor and flexor pollicis brevis and opponens pollicis and the lateral two lumbricals. Histological examination of the tumor demonstrated a hemangioblastoma. von Hippel-Lindau disease was ruled out by genetic testing of the patient's blood. Eight-month postoperatively, all pre-operative symptoms had decreased considerably and the radiographic examination shoved unchanged pedicle screw/rod stabilization of the cervicothoracic junction. Conclusion: Hemangioblastoma is a rare hypervascular tumor very rarely located at the spinal nerve. The tumor should be resected in toto to avoid recurrence and bleeding. In the current case, the location was at the T1 root necessitating complex surgery with laminectomies and hemicorporectomy of T2 and a posterior rib resection/thoracotomy. Spinal stabilization is mandatory. Preferably embolization should be performed preoperatively. T1 transection results in a specific neurodeficit which should be explained to the patient preoperatively. The patients should undergo genetic testing for Hippel-Lindau disease.

Preoperative embolization and microsurgical resection of a cerebellar hemangioblastoma: embolization goals and technical nuances of the approaches. Illustrative case.

BACKGROUND: Resection remains the optimal treatment for hemangioblastomas, highly vascular tumors commonly located in the cerebellum or spinal cord. Preoperative embolization can be used with caution to reduce intraoperative blood loss and promote gross-total resection while reducing neurological morbidity. OBSERVATIONS: The authors report a case of a 44-year-old male who presented with worsening dizziness, gait imbalance, and diplopia. Imaging revealed a large vascular cerebellar mass with brainstem compression and hydrocephalus, concerning for hemangioblastoma. The patient underwent preoperative embolization of the main arterial supply from the right superior cerebellar artery, which devascularized the tumor and reduced the early venous shunting, followed by gross-total resection of the tumor. Preoperative embolization helped to facilitate safe microsurgical resection because this main arterial supply was deep to the planned surgical approach, and the Onyx cast served as a landmark of the dorsal midbrain and remaining arterial supply. This resulted in minimal intraoperative blood loss. At 2-year follow-up, the patient's diplopia and vertigo had resolved, and his gait continues to improve. LESSONS: Despite controversy regarding the use of preoperative embolization for hemangioblastoma resection, the authors emphasize its safety and utility during resection of a large cerebellar hemangioblastoma. Onyx embolization provided benefit in both reducing the tumor blood supply and serving as intraoperative visual guidance.

Patients With Hemangioblastoma: Mood Disorders and Sleep Quality.

BACKGROUND: Sleep has confirmed physical, psychological, and behavioral benefits, and disruptions can result in disturbances in these states. Moreover, it can be linked bidirectionally with susceptibility to and the subsequent status of brain tumors. The current study examined mood disorders and sleep quality before and after surgery for hemangioblastoma brain tumors. METHODS: Thirty-two patients diagnosed with hemangioblastoma brain tumors between 2017 and 2023 underwent surgical treatment. The Karnofsky Performance Status and ECOG performance status scales, the Brunel Mood Scale, the Morningness-Eveningness Questionnaire, and the Mini-Sleep Questionnaire were employed to assess the patients. RESULTS: The findings indicate that after surgery, sleep quality and mood disorders, including tension, vigor, and depression, did not exhibit significant differences in these patients (p>0.05). However, tension, vigor, depression, and sleep quality did have a significant impact on their functional status post-surgery (p<0.05). CONCLUSION: Depression is the significant mood factor in patients with brain tumors that impact their functional status. In this context, it is recommended that psychological therapies be considered for them, alongside conducting more comprehensive and in-depth studies on psychological disorders in patients with brain tumors.

Case report: A cystic capillary hemangioma located at the conus medullaris mimicking hemangioblastoma.

Capillary hemangiomas, usually found in skin and mucosal tissues, are rarely encountered within the spinal cord, presenting a significant diagnostic challenge. We report a rare case of intradural extramedullary capillary hemangioma at the conus medullaris in a 66-year-old female patient. Our initial diagnosis leaned towards a cystic hemangioblastoma based on MRI findings due to the presence of cystic formation with an enhanced mural nodule. However, surgical exploration and subsequent pathological examination revealed the lesion as a capillary hemangioma. To the authors' knowledge, this case may represent the first documented instance of a spinal capillary hemangioma that mimics a cystic hemangioblastoma.

Predictors of Progression in a Series of 81 Adult Patients Surgically Managed for an Intracranial Hemangioblastoma: Implications for the Postoperative Follow-Up.

The aim was to identify predictors of progression in a series of patients managed for an intracranial hemangioblastoma, in order to guide the postoperative follow-up modalities. The characteristics of 81 patients managed for an intracranial hemangioblastoma between January 2000 and October 2022 were retrospectively analyzed. The mean age at diagnosis was of 48 ± 16 years. Eleven (14%) patients had von Hippel-Lindau disease. The most frequent tumor location was the cerebellar hemispheres (n = 51, 65%) and 11 (14%) patients had multicentric hemangioblastomas. A gross total resection was achieved in 75 (93%) patients. Eighteen (22%) patients had a local progression, with a median progression-free survival of 56 months 95% CI [1;240]. Eleven (14%) patients had a distant progression (new hemangioblastoma and/or growth of an already known hemangioblastoma). Local progression was more frequent in younger patients (39 ± 14 years vs. 51 ± 16 years; p = 0.005), and those with von Hippel-Lindau disease (n = 8, 44% vs. n = 3, 5%, p < 0.0001), multiple cerebral locations (n = 3, 17% vs. n = 2, 3%, p = 0.02), and partial tumoral resection (n = 4, 18% vs. n = 1, 2%, p = 0.0006). Therefore, it is advisable to propose a postoperative follow-up for at least 10 years, and longer if at least one predictor of progression is present.

Pre-operative Embolization of a Cerebellar Hemangioblastoma Using Polyvinyl Alcohol (PVA) and Target Tetra 360 Detachable Coil.

Due to its hypervascularity, hemangioblastoma, a rare primary central nervous system intracranial tumor, has been treated with pre-operative embolization prior to surgical resection. Here, we describe a case treated as such. A 37-year-old male presented with worsening chronic headache and right ear tinnitus was found to have a hypervascular, heterogeneous right cerebellar lesion suspicious for arteriovenous malformation or hemangioblastoma. He underwent polyvinyl alcohol (PVA) and Target Tetra 360 (Fremont, CA: Stryker Neurovascular) detachable coil embolization followed by complete tumor resection. Pathology was consistent with hemangioblastoma. He presented with complete resolution of his symptoms immediately post-operatively and at a two-week follow-up. Our case highlighted the importance of pre-operative embolization to help achieve complete tumor resection which is considered curative in the treatment of hypervascular hemangioblastoma. The Target Tetra 360 detachable coil embolization is another material that can be considered.

Screening and surveillance recommendations for central nervous system hemangioblastomas in pediatric patients with Von Hippel-Lindau disease.

PURPOSE: Von Hippel-Lindau (VHL) disease is an autosomal-dominantly inherited tumor predisposition syndrome. One of the most common tumors are central nervous system (CNS) hemangioblastomas. Recommendations on the initiation and continuation of the screening and surveillance program for CNS tumors in pediatric VHL patients are based on small case series and thus low evidence level. To derive more robust screening recommendations, we report on the largest monocentric pediatric cohort of VHL patients. METHODS: We performed a retrospective analysis on a pediatric cohort of 99 VHL patients consulted at our VHL center from 1992 to 2023. Clinical, surgical, genetic, and imaging data were collected and statistically analyzed. RESULTS: 42 patients (50% male) developed CNS hemangioblastomas, of whom 18 patients (56% male) underwent hemangioblastoma surgery (mean age at first surgery: 14.9 ± 1.9 years; range 10.2-17). The first asymptomatic patient was operated on at the age of 13.2 years due to tumor progress. Truncating VHL mutation carriers had a significantly higher manifestation rate (HR = 3.7, 95% CI: 1.9-7.4, p < 0.0001) and surgery rate (HR = 3.3, 95% CI: 1.2-8.9, p = 0.02) compared with missense mutation carriers. CONCLUSION: We recommend starting MRI imaging at the age of 12 years with examination intervals every (1-) 2 years depending on CNS involvement. Special attention should be paid to patients with truncating variants. Affected families should be educated regularly on potential tumor-associated symptoms to enable timely MRI imaging and eventually intervention, as CNS hemangioblastoma may develop before screening begins. GERMAN CLINICAL TRIALS REGISTER REGISTRATION NUMBER: DRKS00029553, date of registration 08/16/2022, retrospectively registered.

Prognostic Factors of Spinal Intramedullary Hemangioblastoma : Analysis of Surgical Outcomes and Tumor Characteristics.

Objective: Spinal intramedullary hemangioblastoma is a rare and highly vascularized benign tumor. The characteristics of the tumor, its corresponding location, and surgical outcomes remain unknown. The purpose of this study was to identify risk factors and strategies for neurologic deterioration following hemangioblastoma surgery. Methods: A comprehensive retrospective analysis was undertaken to evaluate patients who underwent surgical intervention for intramedullary hemangioblastoma at our institution from 1993 to 2022. Patients with at least one year of follow-up data were included. The analysis covered patient demographics, pre- and post-operative Modified McCormick Scale (MMCS), tumor location, and tumor size. Results: This study included 25 cases. One-year after surgery, neurological deterioration was observed in 5 (20.0%) cases, and neurological improvement was found in 9 (36.0%) cases. Five cases were ventrally located, and twelve cases were dorsally located. Ventrally located cases were larger in tumor axial size (p = 0.029) than dorsal location tumors, resulting in poorer follow-up MMCS and a higher prevalence of von Hippel-Lindau syndrome (VHL) (p = 0.042). Three of them were confirmed to be supplied by the anterior spinal artery. In the case of dorsally located cases, there was no neurologic deterioration. Conclusion: In intramedullary spinal cord hemangioblastomas, cases located ventrally had a higher incidence of neurological deterioration following surgery than those located dorsally or in intramedullary extramedullary cases. Ventrally located hemangioblastomas were larger than those in other locations. They were mainly supplied by the anterior spinal artery in VHL patients.

Time course of tumorigenesis of a newly developed sporadic hemangioblastoma in an elderly patient: illustrative case.

BACKGROUND: von Hippel-Lindau disease-associated hemangioblastomas (HBs) account for 20%-30% of all HB cases, with the appearance of new lesions often observed in the natural course of the disease. By comparison, the development of new lesions is rare in patients with sporadic HB. OBSERVATIONS: A 65-year-old man underwent clipping for an unruptured aneurysm of the anterior communicating artery. Fourteen years later, follow-up magnetic resonance imaging (MRI) revealed a strongly enhanced mass in the right cerebellar hemisphere, diagnosed as a sporadic HB. A retrospective review of MRI studies obtained over the follow-up period revealed the gradual development of peritumoral edema and vascularization before mass formation. LESSONS: Newly appearing high-intensity T2 lesions in the cerebellum may represent a preliminary stage of tumorigenesis. Careful monitoring of these patients would be indicated, which could provide options for early treatment to improve patient outcomes.

Longitudinal Pulse-Synchronous Bouncing During Catheter Angiography-A Phenomenon Specific to Spinal Hemangioblastomas.

BACKGROUND: Spinal hemangioblastomas are often evaluated with catheter angiography for both workup and treatment planning. We report a unique longitudinal pulse-synchronous bouncing phenomenon observed during their angiographic evaluation and consider the association of pulse-synchronous bouncing with syringomyelia, another pathologic feature associated with hemangioblastomas. METHODS: Preoperative spinal angiograms and associated magnetic resonance imagings (MRIs) obtained over a 16-year period at a single institution were retrospectively evaluated. Magnetic resonance imaging (MRI) parameters included lesion and syrinx location and size. Angiograms were evaluated for bouncing phenomena. Student's t-test and Chi square test compared characteristics between groups. Linear regression analyses evaluated maximum amplitude of dynamic motion and any associated syrinx. RESULTS: Nineteen hemangioblastoma patients had preoperative angiograms available for review. Eight exhibited bouncing behavior. Between the dynamic and nondynamic cohorts, there was no difference in presence or volume of syrinxes. Lesions in the dynamic cohort trended towards a cervical location (75% vs. 36.3%, P = 0.10). No significant correlation was found between bouncing amplitude and syrinx size (R2 = 0.023). Dural contact may be related to this dynamic behavior since other high-flow lesions like AVMs do not demonstrate this phenomenon, and AVMs are pial-based and more likely to contact stationary dura. Here, there were fewer lesions abutting the thecal sac in the dynamic cohort (50% vs. 81.8%, P = 0.14). CONCLUSIONS: Though no significant relationship was established between this bouncing behavior and syrinx formation, noted trends included a greater range of motion for cervical lesions and limited motion in tumors abutting the thecal sac.

Epidemiology and economic burden of Von Hippel-Lindau Disease-associated central nervous system hemangioblastomas and pancreatic neuroendocrine tumors in the United States.

BACKGROUND: To date, real-world evidence around the clinical and economic burden related to von Hippel-Lindau (VHL) disease is limited. Therefore, this study characterized the prevalence, healthcare resource utilization (HRU), and economic burden of von Hippel-Lindau-associated central nervous system hemangioblastoma (VHL-CNS-Hb) and pancreatic neuroendocrine tumors (VHL-pNET) in the United States (US). METHODS: Patients with VHL-CNS-Hb or VHL-pNET were identified from Optum's de-identified Clinformatics® Data Mart Database (2007-2020) and matched 1:5 to control patients without VHL disease or CNS-Hb/pNET. Prevalence rates of VHL-CNS-Hb and VHL-pNET (standardized by age and sex) in 2019 were estimated. HRU and healthcare costs (2020 US dollars) were compared between the VHL-CNS-Hb/VHL-pNET and control cohorts. RESULTS: In 2019, US prevalence rates of VHL-CNS-Hb and VHL-pNET were estimated to be 1.12 cases per 100,000 (3,678 patients) and 0.12 cases per 100,000 (389 patients), respectively. Patients with VHL-CNS-Hb (N = 220) had more inpatient, outpatient, and emergency department visits and $49,645 higher annual healthcare costs than controls (N = 1,100). Patients with VHL-pNET (N = 20) had more inpatient and outpatient visits and $56,580 higher annual healthcare costs than controls (N = 100). Costs associated with surgical removal of CNS-Hb and pNET were particularly high. CONCLUSIONS: In this retrospective, claims-based study, both VHL-CNS-Hb and VHL-pNET were associated with substantial HRU and healthcare costs, particularly tumor reduction surgery-related costs. These findings provide important insight for healthcare payers regarding the expected real-world costs that enrollees with VHL-CNS-Hb and VHL-pNET may incur over the course of their disease.

A novel presentation of diaphragmatic flutter in a patient with obstructive sleep apnea and recurrent cerebellar hemangioblastoma.

We report a unique case of diaphragmatic flutter in a patient with obstructive sleep apnea who had no respiratory symptoms related to flutter and a history of recurrent cerebellar hemangioblastoma. The flutter was detected during a routine follow-up monitoring through the built-in software of the positive airway pressure device; the flow and pressure curves showed abnormal and curious oscillations. The ultrasound confirmed the diagnosis and ruled out other causes of abnormal diaphragmatic movements. This case report contributes to the scientific literature by presenting a novel case of diaphragmatic flutter associated with recurrent cerebellar hemangioblastoma. It also emphasizes the need for more research on the pathophysiology and treatment of this rare condition. CITATION: Ciorba C, Espinoza Perez JA, Alfonso Imizcoz M, Errasti Viader J, Cebollero Rivas P, De Vito EL. A novel presentation of diaphragmatic flutter in a patient with obstructive sleep apnea and recurrent cerebellar hemangioblastoma. J Clin Sleep Med. 2024;20(2):313-317.

Exceptional and Sustained Response to Belzutifan in Von Hippel-Lindau Disease-Associated Central Nervous System Hemangioblastoma.

Von Hippiel-Lindau (VHL) disease is a rare genetic disorder characterized by a variety of benign and malignant neoplastic growths arising in multiple different organ systems. About 60%-84% of patients develop hemangioblastomas, benign tumors comprised of newly formed blood vessels that often occur in the central nervous system (CNS) and retinas. Treatment options for this disease were limited before the Food and Drug Administration (FDA) approval of belzutifan, a HIF2α inhibitor. We present a case of a 25-year-old woman with VHL who underwent treatment with belzutifan over 18 months. It was noted that her CNS lesions decreased significantly in size over the course of her treatment, and she had minimal adverse effects. Her excellent and sustained therapeutic response to the treatment highlights the real-world clinical benefit of belzutifan and the possibility that this could play a crucial role in treating VHL by postponing or completely avoiding repeated surgical and radiotherapeutic intervention and their associated comorbidities.

Hemangioblastoma and arteriovenous malformation in the same patient: a not random association or two isolated entities? Systematic review starting from a unique case.

BACKGROUND: The association between intracranial hemangioblastomas and arteriovenous malformations has been documented in very few cases in literature since 1965 and might present in three modalities: "intermixed, adjacent and separated (spatially and temporally)". Often, the pattern of presentation is "intermixed". According to our systematic review, we propose an adjustment of the previous classification, specifically for these entities. We describe the first case of a truly "spatially separated" association between these two lesions. METHODS: Our study encompassed all adult patients diagnosed with both intracranial hemangioblastoma and AVM who were evaluated in the last 20-year period, from 2003 to 2023 at Helsinki University Hospital. Cases of this coexistence were retrospectively identified and collected from clinical records. For the systematic review, studies reporting the coexistence of hemangioblastoma and AVM in adult patients (>18 years old) were selected. Given the rarity of this pattern, case reports were also included. RESULTS: The combined analysis of our systematic review and institutional retrospective study revealed a total of only seven identified cases. We applied the classification of neoplasms and AVM by Yano, modifying and adapting it into our screened patient series. We systematically reclassified "adjacent" and genuinely "spatially separated" patterns based on the vascular axis supplying both lesions. CONCLUSIONS: Hemangioblastomas and AVMs rarely coexist in the same patient. Our study reports the first instance of a truly "spatially separated" sporadic association between these vascular lesions. The rarity of such coexistence underscores the need for a nuanced and systematic classification to guide the management of these infrequent cases.

Central Nervous System Dissemination of Solitary Sporadic Supratentorial Hemangioblastoma: A Case Report and Literature Review.

We report a patient with whole neuroaxis dissemination of a sporadic supratentorial hemangioblastoma (HB) for more than 15 years. A 68-year-old female patient presented with severe radiating pain in the right leg. Gadolinium-enhanced lumbar spine MRI showed an intradural mass (2.5 cm in diameter) at the L4 level. The patient had been severely disabled for 22 years after a previous intraventricular brain tumor resection. At that time, the diagnosis was angioblastic meningioma, which was thought to be incorrect. At 14 years after the brain surgery, gamma knife radiosurgery was performed three times for newly developed or recurred supratentorial and infratentorial tumors in the cerebrospinal fluid pathway. The patient underwent lumbar spinal surgery, and a gross total removal of the mass was performed, which confirmed the histopathological diagnosis of HB. We reexamined the old histopathological specimen of the intraventricular tumor from 20 years ago and changed the diagnosis from angioblastic meningioma to supratentorial HB. Six months after spinal surgery, the patient underwent a second spinal surgery and brain surgery, and the histopathological diagnosis was HB following both surgeries, which was the same following the first spinal surgery. Here, we report a sporadic supratentorial HB patient who showed cranial and spinal disseminations for more than two decades along with a literature review.

Belzutifan-induced regression of retinal capillary hemangioblastoma: A case-series.

Purpose: To report a series of three patients with von Hippel-Lindau (VHL) disease who demonstrated regression of their retinal hemangioblastomas (RH) using belzutifan in conjunction with photocoagulation therapy. Observations: Patient 1, a 23-year-old female, presented with multiple RHs in her right eye (OD) that were lasered. Her left eye (OS) revealed a large inferotemporal RH that measured approximately 2.1 mm2. Systemic belzutifan was administered. Four months after initiation of treatment, the lesion regressed to 1.4 mm2, but belzutifan was not well-tolerated and was discontinued due to side effects. At the date of belzutifan discontinuation, the lesion measured about 1.1 mm2. Focal laser photocoagulation was applied. The lesion regressed to around 0.6 mm2. Two additional laser treatments were applied one month later. On the most recent follow-up, the lesion was completely fibrosed.Patient 2, a 32-year-old male, presented with one RH OD and two RHs OS. Belzutifan was administered for one month before the patient began experiencing side effects of the medication. Consequently, the dose of belzutifan was decreased. After one month with the lowered dose, laser coagulation was applied to OS. In the most recent follow-up, five months after the initial presentation, the lesions remain less vascularized and reduced in size.Patient 3, is a 44-year-old male with a large RH OD. Following seven months of belzutifan daily, there was a significant reduction in the RH size. Conclusions: Belzutifan, a hypoxia-inducible factor inhibitor, is an FDA-approved medication for VHL disease associated with renal cell carcinoma, central nervous system hemangioblastomas, or pancreatic neuroendocrine tumors that do not require immediate surgical resection. Because of the high incidence of VHL-associated RHs, adjuvant laser photocoagulation therapy when belzutifan is suspended or withheld can allow for the regression of large lesions. In this case series, we also propose a reproducible and technically simple method to measure RH lesions size, using Optos fundus imaging.