This document summarizes pulmonary sequestration, a congenital malformation where a nonfunctional lung lobe receives its blood supply from the systemic circulation rather than the pulmonary arteries. It can be either extra-lobar, located outside the lung, or intra-lobar, located within the lung. Intra-lobar sequestration is more common and often presents later in life, showing chronic inflammation and fibrosis from recurrent infections. Extra-lobar sequestration typically presents earlier and shows less inflammation since infections have less time to develop. Microscopically, intra-lobar sequestration displays marked chronic inflammation and fibrosis with cyst formation, while extra-lobar sequestration does not usually have

1. FLASHPATH
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2. PULMONARY
SEQUESTRATION
H A Z E M A L I

3. CLINICAL
• Congenital malformation
• Nonfunctioning lung lobe or segment
• Not connected to the airway system
• Not supplied by pulmonary arteries
– Receives blood supply from systemic (aortic) branches
• Either Extra-lobar (outside the lung) or Intra-lobar (within the lung)

4. CLINICAL
Extra-lobar Intra-lobar
Incidence Less common More common
Age of presentation Infants
(below 1 year)
Older children and even
Adults
Gender Male > Females Equal
Foregut communication and
associated anomalies
Very Common
e.g. diaphragmatic hernia
Very rare
Chronic inflammation,
fibrosis and Honeycomb
changes
Very rare Very Common

5. GROSS
Extra-lobar Intra-lobar
Mass Solid, Spongy mass Solid, Fibrotic mass has
multiple, variable-sized
cystic areas
Location Outside the lung
anywhere above, within, or
below the diaphragm
Within the lung
Side Mainly left side Mainly left lung
(lower lobe)
Pleura Its own “separate”
pleural covering
The same pleural
covering of the lung
Venous drainage Systemic (azygous) Pulmonary

6. GROSS
Intra-lobar
sequestration

7. MICROSCOPY
• Intra-lobar:
– Marked chronic inflammation, fibrosis, cystic changes
• May be because it can be undiagnosed for long time,
it shows a higher risk for recurrent infections and fibrosis
– Not associated with CPAM type 2
(Congenital pulmonary airway malformation)
• Extra-lobar:
– No significant inflammation or fibrosis
• May be because it is often discovered early in life,
there is no time to develop infections or fibrosis
– Associated with (CPAM) type 2 in 50% of cases
• Areas of irregular, markedly dilated bronchioles
within parenchyma

8. DIFFERENTIAL DIAGNOSIS
O t h e r c y s t i c l u n g d i s e a s e s :
• Congenital:
– Bronchogenic cysts
– Congenital pulmonary cysts
– Congenital pulmonary airway malformation
– Congenital lobar emphysema
• Acquired:
– Emphysema
– Healed abscess
– Honeycombing
• Mixed:
– Cystic fibrosis

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