Hereditary Hemorrhagic Telangiectasia

KEY FACTS

TERMINOLOGY

• Hereditary hemorrhagic telangiectasia (HHT)

○ Rendu-Osler-Weber, Osler-Weber-Rendu syndrome

• Autosomal dominant disorder with widely distributed,

multisystem angiodysplastic lesions

○ Mucocutaneous telangiectasias with arteriovenous

malformations (AVMs) in visceral organs (primarily lungs,

brain, liver)

IMAGING

• Best diagnostic clue

○ Multiple pulmonary or cerebral malformations

(pAVM/cAVM) in patient with recurrent epistaxis

• MR

○ "Blooming" of capillary telangiectasias (SWI > GRE)

– "Fluffy" enhancement on T1 C+

○ cAVM: Nest ("tangle") of flow voids, gliosis

• Useful: Multislice CT/CTA of lungs and liver

PATHOLOGY

• Genetically heterogeneous disorder caused by mutations in

TGF-β/BMP signaling pathway

○ Endoglin (ENG) mutations cause HHT1

○ Activin A receptor type II-like 1 (ACVRL1/ALK1) mutations

cause HHT2

○ SMAD4 mutations cause the combined Juvenile

Polyposis/HHT syndrome

• 3 types of vascular malformations in HHT

○ Most common: Capillary vascular malformation (61%)

– Tangle of abnormal vessels

– No shunt, no dilated feeding artery or draining vein

○ Nidus-type AVM: 43%

– Dilated network of abnormal vessels

– AV shunting (early draining vein)

○ Direct high-flow arteriovenous fistula: 12%

– Shunt with absence of intervening nidus between

feeding artery, draining vein

(Left) Photograph of a patient

with hereditary hemorrhagic

telangiectasia (HHT), multiple

episodes of severe epistaxis

shows numerous cutaneous

telangiectasias ﬊, with visible

lesions on mucosa of the

mouth ﬈ and nose ﬉. (Right)

Axial FLAIR MR in an 18-yearold man with family history of

HHT was obtained as part of

routine screening. A small left

medial frontal hyperintensity

﬇ with associated flow voids

ſt is present.

(Left) Axial T1 C+ MR in the

same patient shows that the

lesion ﬇ enhances intensely.

(Right) Lateral view of the left

internal carotid DSA obtained

in the same patient shows a

small arteriovenous

malformation (AVM) nidus ﬊

("micro-AVM") with an early

draining vein ﬈. Genetic

profiling showed ENG

mutation.

Trauma, and Stroke

Brain: Pathology-Based Diagnoses: Malformations,

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