Hereditary Hemorrhagic Telangiectasia: Genetics, Pathophysiology, Diagnosis, and Management

Catheter embolization for pulmonary arteriovenous malformations during chemotherapy for appendiceal adenocarcinoma: A case report of associated brain abscess

Pulmonary arteriovenous malformations are rare, abnormal, low-resistance vascular structures that connect a pulmonary artery to a vein. They are common in patients with hereditary hemorrhagic telangiectasia; however, acquired malformations can occur in patients with underlying diseases such as chest trauma, hepatic cirrhosis, and mitral stenosis. Pulmonary arteriovenous malformations bypass the normal pulmonary capillary bed and result in intrapulmonary right-to-left shunts, which may cause central nervous system complications such as brain abscesses or ischemic stroke. Brain abscesses related to pulmonary arteriovenous malformations are not uncommon; however, reports of their occurrence during chemotherapy are limited. Here, we report the case of a 68-year-old woman with bilateral pulmonary arteriovenous malformations and appendiceal adenocarcinoma who developed a bacterial brain abscess during chemotherapy. The infection was treated using abscess drainage and antibiotic therapy. After the brain abscess healed, catheter embolization was performed on the pulmonary arteriovenous malformations and chemotherapy was resumed. The present case suggests that if a patient with a malignancy has a pulmonary arteriovenous malformation, clinicians should pay special attention to complications such as brain abscesses during chemotherapy. For patients who do not urgently need chemotherapy, embolization of the pulmonary arteriovenous malformation before chemotherapy may be a better treatment option.

Hereditary haemorrhagic telangiectasias with recurrent ischemic stroke hinted by manganese deposition in the basal ganglia: a case report and literature review

BACKGROUND

Hereditary hemorrhagic telangiectasia (HHT) is a rare autosomal dominant inherited vascular disorder that can involve multiple organs, thus can be associated with so many clinical departments that proper screening and diagnosis of HHT are needed for providing better management of both patients and their family members.

CASE PRESENTATION

We present a 58-year-old female patient with recurrent paradoxical brain embolism due to HHT. She received aspirin therapy and underwent pulmonary arteriovenous malformation embolization, recovering well and discharged 3 days postoperatively. Though ischemic stroke caused by HHT-induced vascular disorders has been reported, our patient presented with both recurrent paradoxical brain embolisms and radiologic findings of bilateral globus pallidus manganese deposition at the same time, a combination rarely reported. We also review the literature on the clinical features and management of HHT for prompt diagnosis of this genetic disease behind paradoxical embolism.

CONCLUSIONS

When patients with ischemic stroke, especially recurrent ischemic stroke, have combined arteriovenous malformations (AVMs) in single or multiple organs, or clues for AVMs like manganese deposition in globus pallidus, genetic diseases such as HHT may be the reason for ischemic stroke and shouldn't be missed in the evaluation of embolic sources.

Molecular and Functional Cargo of Plasma-Derived Exosomes in Patients with Hereditary Hemorrhagic Telangiectasia

Background: Hereditary Hemorrhagic Telangiectasia (HHT) is a genetic disorder leading to frequent bleeding in several organs. As HHT diagnosis is demanding and depends on clinical criteria, liquid biopsy would be beneficial. Exosomes from biofluids are nano-sized vesicles for intercellular communication. Their cargo and characteristics represent biomarkers for many diseases. Here, exosomes of HHT patients were examined regarding their biosignature. Methods: Exosomes were isolated from the plasma of 20 HHT patients and 17 healthy donors (HDs). The total exosomal protein was quantified, and specific proteins were analyzed using Western blot and antibody arrays. Human umbilical vein endothelial cells (HUVECs) co-incubated with exosomes were functionally examined via immunofluorescence, proliferation, and scratch assay. Results: The levels of the angiogenesis-regulating protein Thrombospondin-1 were significantly higher in HHT compared to HD exosomes. Among HHT, but not HD exosomes, a negative correlation between total exosomal protein and soluble Endoglin (sENG) levels was found. Other exosomal proteins (ALK1, ALK5) and the particle concentration significantly correlated with disease severity parameters (total consultations/interventions, epistaxis severity score) in HHT patients. Functionally, HUVECs were able to internalize both HD and HHT exosomes, inducing a similar change in the F-Actin structure and a reduction in migration and proliferation. Conclusions: This study provided first insights into the protein cargo and function of HHT-derived exosomes. The data indicate changes in sENG secretion via exosomes and reveal exosomal Thrombospondin-1 as a potential biomarker for HHT. Several exosomal characteristics were pointed out as potential liquid biomarkers for disease severity, revealing a possible new way of diagnosis and prognosis of HHT.

The Role of Thalidomide and Its Analogs in the Treatment of Hereditary Hemorrhagic Telangiectasia: A Systematic Review

Background: Hereditary hemorrhagic telangiectasia (HHT) is a disease characterized by arteriovenous malformations and telangiectases, in which the endothelium and immune system play a role in the pathophysiology. Therefore, treatments with antiangiogenic properties which are also regarded as immunomodulators were demonstrated to play an important role in treatment. This systematic review aimed to gather the accumulated information of the use of thalidomide and its analogs in the treatment of HHT. Methods: In this systematic review, publications that were published up to March 2024 and met the inclusion criteria were compiled using the keywords 'thalidomide', 'lenalidomide', 'pomalidomide', 'immunomodulatory drugs' and 'HHT' in Medline and Scholars databases. Results: A total of 53 articles were evaluated and 15 were included in the study. Thalidomide was the predominant used agent and was observed to be used in patients with ages ranging from 37 to 77 years, with doses ranging from 50 to 200 mg daily, and the mean follow-up period was observed to be 6-60 months. Assessments regarding efficacy were based on the epistaxis severity score (ESS), hemoglobin level, and transfusion independence. While thalidomide showed significant efficacy, it also had an adverse event rate of any severity of up to 85% of patients. Use of lenalidomide to control bleeding in HHT was reported in a single case report, while the use of pomalidomide was observed to be investigated in Phase 1 and Phase 2 studies in patients aged 48 to 70 years, with doses ranging from 1 to 5 mg daily for 6-24 months. This treatment was reported to provide significant improvement in hemoglobin levels and ESS. Adverse events of any severity were observed at a frequency of 60-66%. Conclusions: Antiangiogenic agents such as thalidomide, lenalidomide, and pomalidomide may be effective in managing HHT. However, further studies are needed to optimize the timing, dose, and sequence.

Ischemic cholangitis: Lethal complication of Osler-Weber-Rendu disease

Osler-Weber-Rendu disease (OWRD), also known as hereditary haemorrhagic telangiectasia (HHT), is an autosomal dominant genetic disorder characterised by arteriovenous malformations in several organs. Ischemic cholangitis is a rare life-threatening complication of OWRD, with only a few documented cases in the literature. A liver transplant is the main curative treatment. In this paper, we report a case of a 33-year-old woman with a history of recurrent epistaxis, admitted with abdominal pain and fever, physical examination found multiple cutaneous and mucosal telangiectasias and the biological workup showed cholestasis, abdominal imaging identified arterio-venous shunts and multiple cystic hepatic lesions, one of them seemed to communicate with an intrahepatic biliary duct, finally the diagnosis of ischemic cholangitis due to OWRD was retained and antibiotic treatment has been initiated. We review the various therapeutic options available to improve the management of this fatal complication.

Management of hereditary hemorrhagic telangiectasia-like symptoms induced by trastuzumab emtansine in a breast cancer patient: case report

Trastuzumab emtansine (T-DM1) is a targeted therapy combining trastuzumab and emtansine for human epidermal growth factor receptor 2(HER2)-positive breast cancer, with common side effects including fatigue, nausea, pain, headache, low platelet count, and elevated liver enzymes. Hereditary Hemorrhagic Telangiectasia (HHT) is an autosomal dominant vascular dysplasia characterized by vascular malformations and telangiectasias in various organs. We present a case of a female patient with advanced breast cancer who developed HHT-like symptoms while on T-DM1 treatment. A 59-year-old woman treated with radiotherapy and T-DM1 every 21 days developed recurring nosebleeds and mucocutaneous and liver telangiectasias indistinguishable from HHT three months after receiving the first dose of T-DM1. Other organ vascular malformations were ruled out through screening protocols. The patient had no previous HHT symptoms or family history. Nasal care measures like lubrication and antifibrinolytics (tranexamic acid) were provided. In addition, propranolol was also prescribed due to its antiangiogenic and antitumoral properties, leading to significantly decreased epistaxis and telangiectasias. Microtubule disruptions caused by T-DM1, along with other angiogenic mechanisms may contribute to the development of telangiectasias resembling HHT. The use of propranolol, an initial approach for HHT, proved to be effective in this case. It is crucial for oncologists and HHT specialists to be aware of this rare adverse event associated with T-DM1 and to implement appropriate management strategies.

Survival strategies: How tumor hypoxia microenvironment orchestrates angiogenesis

During tumor development, the tumor itself must continuously generate new blood vessels to meet their growth needs while also allowing for tumor invasion and metastasis. One of the most common features of tumors is hypoxia, which drives the process of tumor angiogenesis by regulating the tumor microenvironment, thus adversely affecting the prognosis of patients. In addition, to overcome unsuitable environments for growth, such as hypoxia, nutrient deficiency, hyperacidity, and immunosuppression, the tumor microenvironment (TME) coordinates angiogenesis in several ways to restore the supply of oxygen and nutrients and to remove metabolic wastes. A growing body of research suggests that tumor angiogenesis and hypoxia interact through a complex interplay of crosstalk, which is inextricably linked to the TME. Here, we review the TME's positive contribution to angiogenesis from an angiogenesis-centric perspective while considering the objective impact of hypoxic phenotypes and the status and limitations of current angiogenic therapies.

The double whammy of ER-retention and dominant-negative effects in numerous autosomal dominant diseases: significance in disease mechanisms and therapy

The endoplasmic reticulum (ER) employs stringent quality control mechanisms to ensure the integrity of protein folding, allowing only properly folded, processed and assembled proteins to exit the ER and reach their functional destinations. Mutant proteins unable to attain their correct tertiary conformation or form complexes with their partners are retained in the ER and subsequently degraded through ER-associated protein degradation (ERAD) and associated mechanisms. ER retention contributes to a spectrum of monogenic diseases with diverse modes of inheritance and molecular mechanisms. In autosomal dominant diseases, when mutant proteins get retained in the ER, they can interact with their wild-type counterparts. This interaction may lead to the formation of mixed dimers or aberrant complexes, disrupting their normal trafficking and function in a dominant-negative manner. The combination of ER retention and dominant-negative effects has been frequently documented to cause a significant loss of functional proteins, thereby exacerbating disease severity. This review aims to examine existing literature and provide insights into the impact of dominant-negative effects exerted by mutant proteins retained in the ER in a range of autosomal dominant diseases including skeletal and connective tissue disorders, vascular disorders, neurological disorders, eye disorders and serpinopathies. Most crucially, we aim to emphasize the importance of this area of research, offering substantial potential for understanding the factors influencing phenotypic variability associated with genetic variants. Furthermore, we highlight current and prospective therapeutic approaches targeted at ameliorating the effects of mutations exhibiting dominant-negative effects. These approaches encompass experimental studies exploring treatments and their translation into clinical practice.

Hereditary Hemorrhagic Telangiectasia in a Patient Undergoing Hemodialysis with Anticoagulants and Antiplatelets

Hereditary hemorrhagic telangiectasia (HHT) is an autosomal dominant disorder that causes abnormal blood vessel formation and bleeding. We herein report a 61-year-old woman with aggravated HHT symptoms after hemodialysis initiation. She was diagnosed with HHT based on her recurrent bleeding, abnormal blood vessel formation, and family history. Despite bleeding complications, the patient required anticoagulants and antiplatelet agents to treat cardiovascular complications. Eventually, the patient died of extensive cerebral hemorrhaging. Our experience suggests that special attention should be paid to bleeding complications in high-risk patients.

A Rare Association: Hereditary Hemorrhagic Telangiectasia with Liver Cirrhosis Causing Portal Hypertension

Hereditary hemorrhagic telangiectasia (HHT), also known as Rendu-Osler-Weber syndrome, is a vascular disorder of autosomal dominant etiology. The hallmark clinical feature is the presence of recurrent episodes of epistaxis in patients with vascular malformations and a tendency to bleed. We present the case of a 71-year-old woman who presented to the emergency department with upper gastrointestinal bleeding caused by esophageal varices, in conjunction with gastric angiodysplasias. The presence of oronasopharyngeal telangiectasias and hepatomegaly raised suspicion of HHT. The diagnostic workup confirmed the presence of angiodysplasia in the gastric region, portal arteriovenous malformation, and a pulmonary shunt.

Multifocal Abscesses, Necrotizing Fasciitis, Iron Deficiency Anemia, and Hypophosphatemia Induced by Ferric Carboxymaltose Infusions: Report of a Case of Hereditary Hemorrhagic Telangiectasia

Hereditary hemorrhagic telangiectasia (HHT) is a rare autosomal dominant vascular dysplasia in which disrupted angiogenesis leads to increased formation of mucocutaneous telangiectasias or major vascular malformations. Iron deficiency anemia and recurrent abscesses are commonly reported in these patients, reinforcing screening and targeted therapies for these conditions. We report a 50-year-old man with HHT affected by repeated episodes of iron deficiency anemia secondary to recurrent epistaxis requiring frequent intravenous iron infusions. He eventually developed hypophosphatemia and hyperphosphaturia secondary to ferric carboxymaltose. He also had a history of recurrent multifocal abscesses, including a severe presentation of necrotizing fasciitis, requiring multiple surgical interventions. Despite the identification of hypogammaglobulinemia, only after consistent dental treatment and antibiotic prophylaxis did the abscesses stop recurring. We highlight the need for careful consideration of all possible complications inherent to the disease itself but also those related to comorbidities or existing treatments.

Current guidelines for diagnosis and management of hepatic involvement in hereditary hemorrhagic teleangiectasia

Hereditary hemorrhagic teleangiectasia (HHT), also known as Rendu-Osler-Weber syndrome, is the most common cause of hepatic vascular malformations in adults. Different vascular shunts (arteriovenous, arterioportal or portovenous) lead to different clinical manifestations. Even though no hepatic-related symptoms are reported in the majority of cases, the severity of liver disease could lead to refractory medical conditions, in some cases requiring liver transplantation. The aim of this manuscript is to provide an updated overview of the current evidence regarding the diagnosis and treatment of HHT liver involvement and liver-related complications.

[Hereditary hemorrhagic telangiectasia]

Hereditary hemorrhagic telangiectasia, also known as Rendu-Osler - Weber disease, is a rare, autosomal dominant vascular disease, with prevalence of 1/5,000. The condition is characterized by muco-cutaneous telangiectasias, which are responsible for a hemorrhagic syndrome of variable severity, as well as arteriovenous malformations (AVMs) appearing in the lungs, the liver, and the nervous system. They can be the source of shunts, which may be associated with high morbidity (neurological ischemic stroke, brain abscess, high-output heart failure, biliary ischemia…). It is therefore crucial to establish a clinical diagnosis using the Curaçao criteria or molecular diagnosis based on genetic analysis of the ENG, ACVRL1, SMAD4 and GDF2 genes. In most cases, multidisciplinary management allows patients to have normal life expectancy. Advances in interventional radiology and better understanding of the pathophysiology of angiogenesis have resulted in improved therapeutic management. Anti-angiogenic treatments, such as bevacizumab (BVZ, an anti-VEGF antibody), have proven to be effective in cases involving bleeding complications and severe liver damage with cardiac repercussions. Other anti-angiogenic agents are currently being investigated, including tyrosine kinase inhibitors.

An Unusual Cause of Right Heart Dysfunction and High Output Heart Failure in a Young Woman

A 35-year-old female presented to our emergency department with clinical signs of acute heart failure. Clinical workup identified severe right heart (RH) dilation and dysfunction with a crossing membrane structure in the right atrium. Right heart catheterization confirmed high output heart failure (HOHF), pulmonary hypertension (PH), and left-to-right blood shunting followed by the documentation of multiple liver and pulmonary arteriovenous malformations (AVMs). Hereditary Hemorrhagic Telangiectasia (HHT) diagnosis was made according to clinical criteria and was established as the cause of HOHF because of chronic volume overload from systemic to pulmonary shunts. With this illustrative case, we aim to discuss the broad spectrum of clinical manifestations of HHT and the unusual phenotype of HOHF secondary to HHT. This case also highlights the broad diagnosis of atrial echocardiographic abnormalities and cardiac structural distortion secondary to high output that can be misleading at imaging evaluation.