Hereditary haemorrhagic telangiectasia (Osler–Weber–Rendu) !

An inherited blood vessel disorder that causes repeated nosebleeds, red spots on lips and fingers, and abnormal vessels in the lungs, brain and liver.

Updated 2026-11-01

Structures involved

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Why it happens

What it is

An autosomal dominant disorder of blood vessel development in which arteries connect directly to veins without capillaries. Small connections in the skin and mucosa form telangiectasias that bleed easily; larger arteriovenous malformations (AVMs) occur in the lungs, brain, liver and gut.

Who gets it

It affects roughly 1 in 5,000 to 10,000 people in all ethnic groups, men and women equally. Nosebleeds usually begin in childhood, skin telangiectasias appear by adulthood, and many patients go years without a diagnosis because nosebleeds are so common in the general population. Latin American series describe the same features; in Colombia it is often first recognised in otorhinolaryngology clinics.

Causes

Pathogenic variants in ENG (HHT type 1) or ACVRL1/ALK1 (HHT type 2)
SMAD4 variants cause combined juvenile polyposis and HHT
GDF2 and other rarer genes
Autosomal dominant inheritance: each child of an affected parent has a 50% chance

Risk factors

A parent, sibling or child with HHT
Dry air, nasal trauma and anticoagulant or antiplatelet drugs worsen bleeding
Pregnancy raises the risk of complications from lung AVMs

Pathophysiology

The affected genes encode parts of the TGF-beta / BMP9 signalling pathway in endothelial cells, which controls how new vessels mature. With half the normal signal, vessels exposed to a second trigger (injury, inflammation) grow into dilated, thin-walled direct artery-to-vein channels. In the nose and gut these rupture with minor trauma. Lung AVMs form a right-to-left shunt that lets clots and bacteria bypass the lung filter, causing stroke and brain abscess, and they lower oxygen saturation. Liver AVMs can cause high-output heart failure, portal hypertension or biliary ischaemia.

Classification

HHT1 (ENG): more lung and brain AVMs, earlier symptoms
HHT2 (ACVRL1): more liver AVMs
Juvenile polyposis–HHT overlap (SMAD4)
Curaçao clinical criteria: definite with 3 or 4, possible with 2 of recurrent spontaneous epistaxis, mucocutaneous telangiectasias, visceral AVMs and a first-degree relative with HHT

Symptoms and signs

Recurrent spontaneous nosebleeds, often from childhood and the most common symptom
Small red or purple spots on the lips, tongue, face, fingertips and nasal mucosa that blanch with pressure
Tiredness and pallor from iron-deficiency anaemia
Black stools or gut bleeding, mostly after age 50
Breathlessness, cyanosis or clubbing from lung AVMs
Headache or seizures from brain AVMs

Diagnosis

Clinical: Based on the Curaçao criteria and a careful family history; examine lips, tongue, palate, fingers and nasal mucosa. Once suspected, patients are screened for visceral AVMs even without symptoms.
Tests: Full blood count and ferritin for iron-deficiency anaemia; pulse oximetry; genetic testing for ENG, ACVRL1 and SMAD4 confirms the diagnosis and allows family screening. Endoscopy for gut bleeding, and colonoscopy for polyps in SMAD4 carriers.
Imaging: Transthoracic contrast (bubble) echocardiography to screen for lung AVMs, followed by chest CT when positive; brain MRI to screen for cerebral AVMs; Doppler ultrasound or CT of the liver when liver AVMs are suspected.

Differential diagnosis

Common anterior epistaxis without systemic disease
Bleeding disorders such as von Willebrand disease
CREST/limited systemic sclerosis (telangiectasias)
Spider angiomas of liver disease
Isolated angiodysplasia of the gut
Sporadic cerebral or pulmonary AVM

Goal of treatment

Reduce nosebleeds and gut bleeding, correct iron deficiency, and find and treat lung and brain AVMs before they cause stroke, abscess or haemorrhage.

Treatment

Conservative: Nasal moisturisers, saline and humidification to protect the mucosa; gentle compression for acute nosebleeds and avoiding nasal packing that tears vessels when possible.
Medical: Iron replacement (oral or intravenous) and transfusion for anaemia; antifibrinolytics such as tranexamic acid, and anti-angiogenic therapy (bevacizumab) or other agents for severe bleeding in specialist centres.
Procedure: Laser or other ablation of nasal and gut telangiectasias; septodermoplasty or nasal closure for refractory epistaxis.
Procedure: Transcatheter embolisation of lung AVMs with a feeding artery large enough to treat; brain AVMs are managed by neurosurgery, embolisation or radiosurgery depending on risk.
Follow-up: Antibiotic prophylaxis before dental and other procedures and air filters on intravenous lines when lung AVMs are present; repeat screening and family testing; nursing care includes teaching first aid for nosebleeds and monitoring haemoglobin.

Complications

Chronic iron-deficiency anaemia and transfusion dependence
Ischaemic stroke and brain abscess from paradoxical embolism
Brain haemorrhage
Hypoxaemia and haemothorax from lung AVMs
High-output heart failure, portal hypertension and pulmonary hypertension from liver AVMs
Colorectal cancer risk in SMAD4 juvenile polyposis

Prognosis

Life expectancy is close to normal when visceral AVMs are found and treated early, but quality of life is often limited by bleeding and anaemia. Untreated lung AVMs carry a substantial risk of stroke and brain abscess.

Prevention

Screening of affected people and their relatives for lung and brain AVMs
Antibiotic prophylaxis before dental procedures when lung AVMs are present
Genetic counselling for families

Test yourself

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What is the inheritance pattern of hereditary haemorrhagic telangiectasia?

Autosomal dominant (ENG, ACVRL1, SMAD4).

What is the most common symptom of HHT?

Recurrent spontaneous nosebleeds (epistaxis).

Why do lung AVMs in HHT cause stroke and brain abscess?

They form a right-to-left shunt that lets clots and bacteria bypass the lung capillaries and reach the brain.

What test screens for pulmonary AVMs in HHT?

Transthoracic contrast (bubble) echocardiography, confirmed by chest CT.

What are the four Curaçao criteria?

Recurrent spontaneous epistaxis, mucocutaneous telangiectasias, visceral AVMs and a first-degree relative with HHT.

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Educational information, not medical advice. For any symptom, see a health professional.

Sources: Hereditary hemorrhagic telangiectasia (MedlinePlus Genetics (U.S. National Library of Medicine), 2020); About Hereditary Hemorrhagic Telangiectasia (HHT) (Centers for Disease Control and Prevention (CDC), 2024).

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Representative model, for educational purposes only.

Nasal septum highlighted on the Durgical 3D model