Developmental abnormalitis

Question 1

Pulmonary arteriovenous malformation (PAVM)

Answer 1

Pathology:

• Abnormal communication between pulmonary arteries and veins
• Left to right shunting
• Congenital:
  
  • Hereditary Hemorrhagic Telangiectasia accounts for 90% of PAVM, autosominal dominant, genetic testing available
• Acquired:
  
  • Hepatopulmonary syndrome
  • Systemic diseases
  • Venous anomalies,

Clinical:

• Asymptomatic (single PAVM <2cm)
• Symptomatic (by age 20): hemorrhage, paradoxical CNS embolism and abscess
• 10% identified in infancy or childhood

Rx: Embolisation, reacannalisation 20%. Requires long term follow up.

Imaging: CT-A gold standard

• Smoothly marginated, avidly enhancing round/oval nodule + feeding artery/vein
• Size: 1-5cm
• Location: peripheral lower lobe dominance
• Simple: 1 or more feeding arteries from same segmental artery
• Complex (10%): multiple feeding arteries from DIFFERENT segmental arteries.
• Nuclear medicine (Tc99m): determine amount of shunt

Diagnosis:

• Genetic mutation testing (80%)
• Contrast ECHO: help determine intracardiac vs intrapulmonary shunt
• Clinical diagnosis (other AVM, epistaxis, FHx of HHT, telangiectases)

DDx:

• Mets
• Septic emboli
• Solitary pulmonary nodule
• Pulmonary artery pseudoaneruysm

https://app.statdx.com/document/pulmonary-arteriovenous-malformati-/cf39a4bd-9573-4b54-b8db-4b174f268b4f?searchTerm=PAVM

Question 2

Partial anomalous pulmonary venous return

Answer 2

Pathology:

• Pulmonary veins drain into systemic veins rather than left atrium
• Associations:
  
  • Right PAPVR into SVC: sinus venosus ASD
  • Scimitar syndrome: ASD, extralobar sequestrations, systemic blood supply to lung, horseshoe lung, PAVM
• Left to right Shunting: 2 or more PAPVR with venosus ASD

CLINICAL:

• asymptomatic
• Shunting: SOB, palpitations, Chest pain, tachycardia, pulmonary oedema

Prognosis: dependent on association conditions.

Rx: surgical correction

Imaging: CECT

• Demonstration of abnormal pulmonary venous drainage:
  
  • LUL PAPVR: drains to left brachiocephalic/coronary sinus/hemiazygos/subclavian
  • RUL PAPVR: drains to right middle lobe pulmonary vein, SVC, azygos, IVC, hepatic/portal vein, associated with sinus venosus ASD
  • RLL PAPVR: scimatar syndrome drains LLL/RML/RLL,UL into IVC
• Evidence of left to right shunt:
  
  • cardiomegaly
  • pulmonary hypertension
• Ancillary:
  
  • Persistant left SVC,
  • Azygos continuation of IVC
• MRI: can quantify shunt

DDx:

• Persistant left SVC
• Lateralisation of aortopulmonary reflection
• Pulmonary Varix
• Left superior intercostal vein

https://app.statdx.com/document/partial-anomalous-pulmonary-venous-/6c051f77-2def-40d3-b4f9-256673bde47f?searchTerm=partial%20anomalous%20pulmonary%20venous%20return

Question 3

Scimitar Syndrome

Answer 3

PATHOLOGY:

• Congenital : scimitar vein/s drians right lung (entire vs RLL) –> courses anterior to hilum –> IVC (most commonly infradiaphragmatic) and less commonly hepatic/portal/azygos vein, coronary sinus, right atrium.
• LUNG: lobar agenesis to focal hypoplasia
• Pulmonary arterial supply: absent, hypoplastic or normal. Systemic supply from thoracic/abdominal aorta to right lower lobe.
• Associated abnormalities in INFANTILE form: ASD (80%) > PDA (75%) > VSD (30%)> Pulmonary Stenosis (20%), coarctations, subaortic stenosis, aortic arch hypoplasia, Tetralogy of Fallot, persistant let SVC
• Associated anomalies in PEDIATRIC/ADULT form: ASD, ostium secundum, PDA, persistant left SVC, cononary artery fistula, azygos continuation of IVC, cor triatrium
• Other associated anomolies:
  
  • Airway anomlies: bronchiectasis, left bronchial isomerism, hyoplasia of right bronchial tree
  • Hemivertebra, scoliosis
  • Bronchogenic cyst
  • Accessory diaphragm
  • Diaphragmatic hernia
  • Horseshoe lung

Epi:

• 1:100000
• Bimodal: infantile vs pediatric/adult form

CLINICAL:

• Infantile form: severe tachypnoea, cyanosis, CHF, L:R shunt. Poorer prognosis.
• Pediatric/adult form: absent or mild symptoms, recurrent pneumonia, hemopytsis, good prognosis
• TRIAD:
  
  • Respiratory distress
  • Right lung hypoplasia
  • Dextroposition

IMAGING:

• PAPVR: Scimitar vein (curved tubular opacitity) extends from right mid-lung towards mid line and most commonly to i_nfra diaphragmatic IVC_
• Cardiac:
  
  • dextroposition
  • normal/hypoplastic/absent pulmonary artery
  • pulmonary hypertension
  • systemic arterialisation of lung from aorta
• Pulmonary:
  
  • Hypoplastic right lung (none to focal to lobar) +/- mosaic perfusion of hypoplastic lung
  • Bronchiectasis (recurrent infection)
  • Absent minor fissure
  • Horseshoe lung
• Other:
  
  • bronchogenic cyst
  • bronchial diverticula
  • accessory diaphgram
  • diaphragmatic hernia

DDx:

• Unilateral abscence of Pulmonary artery
• Pulmonary sequestration
• Meandering Pulmonary vein
• Swyer-James syndrome

https://app.radprimer.com/document/fd549415-b685-46c3-95a2-a9364f6ff204/lesson/c1b9829c-178a-4847-b7bb-d420923a138c

Question 4

Azygos and hemizygos continuation of IVC