Hereditary hemorrhagic telangiectasia (HHT/Osler-Weber-Rendu)

AD; ENG (HHT1), ACVRL1/ALK1 (HHT2), SMAD4 (JP-HHT)

• Mucocutaneous telangiectasias (lips, tongue, fingers)
• Recurrent epistaxis
• Visceral AVMs: pulmonary, hepatic, cerebral, GI
• SMAD4: overlap with juvenile polyposis

Complications:

• Pulmonary AVMs → stroke, brain abscess (paradoxical emboli)
• GI bleeding
• High-output heart failure (hepatic AVMs)

• Clinical diagnosis by Curaçao criteria (definite if ≥3 of 4): recurrent spontaneous epistaxis, mucocutaneous telangiectasias, visceral AVMs (pulmonary, hepatic, cerebral, GI), and a first-degree relative with HHT
• Genetic testing (ENG, ACVRL1, SMAD4) confirms the diagnosis and enables cascade screening of at-risk relatives
• Screening for occult AVMs: contrast echocardiography (bubble study) for pulmonary AVMs, MRI for cerebral AVMs; consider SMAD4 testing for combined juvenile polyposis-HHT (adds GI/colon surveillance)

• Embolization of pulmonary AVMs to prevent paradoxical embolic stroke and brain abscess; antibiotic prophylaxis for dental/surgical procedures in patients with pulmonary AVMs
• Epistaxis: humidification and topical measures first-line; antifibrinolytics (tranexamic acid) and bevacizumab for refractory bleeding
• Iron supplementation/transfusion for chronic blood-loss anemia
• Cerebral AVMs managed individually (embolization, surgery, or radiosurgery) by a multidisciplinary team