Hereditary Haemorrhagic Telangiectasia (HHT)

Question 1

Telangiectasia is ______ either __ or __.

HHT represents dilatation of __ over the __ and __, as well as __
AVM in HHT can affect (7)
HHT is also known as __

Answer 1

Dilatation of small blood vessels - capillaries or venules

HHT - dilatation of post-capillary venules over the skin and mucous membrane, arteriovenous malformations
Also known as Osler-Weber-Rendu syndrome

AVM sites:
1. Nasopharynx
2. Central venous system
3. Lung
4. Liver
5. Spleen
6. Urinary tract
7. Gastrointestinal tract

Question 2

Genetics of HHT

Answer 2

Autosomal dominant
1. Endoglin - chromosome 9
2. ALK-1 - chromosome 12
3. SMAD4 - chromosome 18
4. Unidentified - chromosome 5

All involved in signalling of TGF-B

Question 3

What are causes of telangiectasia?

Answer 3

1. HHT
2. Systemic sclerosis
3. Pregnancy
4. Mitral stenosis
5. Myxoedema
6. Carcinoid syndrome
7. Ataxia telangiectasia
8. Hepatic failure
9. Polycythaemia
10. Dermatomyositis
11. SLE
12. Radiation therapy
13. Necrobiosis lipoidica diabeticorum
14. Granuloma annulare
15. Lupus pernio
16. Topical steroids
17. Essential telangiectasia
18. Temperate/cold climates

Question 4

Clinical presentation of HHT

Answer 4

1. Multiple telangiectases - small < 5mm purplish stains (macular, papular or punctate) that partially blanch with pressure,
   - Face, ears, mouth, lips, under the tongue, buccal and nasal mucosa
   - Arms, hands, nail beds, trunk, feet
   - Conjunctiva
2. Iron deficiency anaemia - pallor, koilonychia
3. Complications
   A. Bleeding: epistaxis, haemoptysis, BGIT
   B. Pulmonary AVM - clubbing, cyanosis, portal HTN
   C. High output cardiac failure
   D. Hepatomegaly, splenomegaly, cirrhosis
   E. Retinal haemorrhage, retinal detachment
   F. AVM, ICB or ischaemic stroke
   G. Cerebral abscess
4. Absence of other diagnosis - systemic sclerosis

Question 5

Pulmonary AVM in HHT can lead to __
Small AVM (<25% pulmonary blood flow): __
Large AVM (>25%): Symptoms (3). Signs (4)

Occurrence of __ and __ is associated with __ and __
Mortality rate: __

Answer 5

Left to right shunting

Small AVM: exertional dyspnoea
Large AVM: dyspnoea, fatigue, haemoptysis. Signs of clubbing, cyanosis, polycythaemia, bruits over lung fields

Occurrence of cyanosis and clubbing -> stroke and cerebral abscess
Mortality rate: 10%

Question 6

Neurological complications of HHT

Answer 6

1. AVM, of which 7% mycotic aneurysm
   - Migraine in 50% patients
   - Rupture - subarachnoid haemorrhage
2. Paradoxical embolism from left-to-right pulmonary AVM
   - Cerebral abscess - actinomyces
   - Ischaemic stroke
3. Spinal AVM -> paraparesis

Question 7

HHT can lead to __ due to high output cardiac failure and AVM
Conversely, AVM shunting from __ and __ to __ can cause high output cardiac failure
Features of (6)

Mesenteric arterial steal syndrome - ____

Answer 7

Portal hypertension
Hepatic artery and portal vein -> hepatic vein

Features:
1. Jaundice
2. RUQ pain
3. Hepatomegaly
4. Splenomegaly
5. Cirrhosis
6. Encephalopathy

Mesenteric steal syndrome - mesenteric angina (abdominal pain)

Question 8

Shovlin’s Criteria for HHT

Answer 8

3 of the following:
1. Recurrent epistaxis
2. Telangiectasia at site other than nasal mucosa
3. Autosomal dominance inheritance
4. Visceral involvement

Question 9

Management of HHT

Answer 9

1. Multidisciplinary team approach depending on complications
2. Anaemia - iron supplement, blood transfusion
3. Skin - cosmetics, laser ablation
4. Epistaxis - cauterisation, laser ablation, septal dermatoplasty, oestrogen therapy, aminocaproic acid
5. Pulmonary AVM - embolisation, resection and ligation
6. GI telangiectasis - blood transfusion, photocoagulation