Article Type : Case Report
Authors : Tan C and Kumar P
Keywords : Adult bronchopulmonary sequestration; Intralobar; Extralobar
A rare congenital malformation of the
respiratory tract, bronchopulmonary sequestration, may present symptomatically
early on in childhood or adolescent years. Adult bronchopulmonary sequestration
is typically an incidental finding found on thoracic imaging. There is
currently 4 known types of bronchopulmonary sequestration. Intralobar
sequestrations are the most common of them. Extralobar sequestration is totally
separate from the lung and has a distinct pleural covering. Extralobar
sequestration has no communication with the airway, and the chance of it
becoming symptomatic in adults is very small. We present herein a case of
extralobar sequestration that caused hemoptysis.
Bronchopulmonary
sequestration (BPS), simply known as pulmonary sequestration, is a rare type of
congenital lung malformation of the lower airway. Whereby a non-functional mass
of lung parenchyma is present but lacks a tracheobronchial connection to the
rest of the functioning airway. This mass then receives its arterial blood
supply through the systemic circulation [1]. Currently, BPS accounts for
approximately 3% of all congenital lung malformations. Congenital lung
malformation account for approximately 10% of all congenital anomalies, while
BPS accounts for just 1-3% of all congenital lung malformations [2]. This case
report describes this rare condition in a 56-year-old healthy female which
manifested initially as haemoptysis.
A 56-year-old woman was
referred to the respiratory clinic after a CT scan showed an incidental finding
of a possible BPS. The CT scan was initially done due to multiple episodes of
haemoptysis, however when she was reviewed in the clinic, she was largely
asymptomatic except for notable exertional dyspnoea. Just prior to the referral
to the respiratory clinic, she was seeing a cardiologist who have worked up and
determine there to be no cardiac cause of her exertional dyspnoea. She is
otherwise well, generally healthy and has no constitutional symptoms. She has
completely recovered from a recent episode of pneumonia which was managed
entirely with oral antibiotics. Her medical history is notable for
hypothyroidism of which she is on daily oral Thyroxine for. She also takes
estrogen for her menopausal symptoms. She is not aware of any known birth
defects. She has worked in an office environment as a receptionist for 40
years. Her family history was unremarkable. She was a previous smoker with a 15
pack years. On examination, she is of a lean body habitus, does not use any
accessory oxygenation devices or puffers. She was afebrile, had a respiratory
rate of 12, and her oxygen saturations were 98% at room air. There was no
evidence of respiratory distress or chronic hypoxemic states. There was no
clubbing or appreciable cervical or axillary lymphadenopathy. There was a dull
percussion note with mildly decrease air entry on her left middle to lower
zone. The rest of her systems examination was unremarkable.
Bloodwork done for her showed a mild normocytic anaemia but was confirmed to be at baseline when looking at previous blood results. Her kidney, liver and thyroid functions were unremarkable. Her C reactive protein (CRP) and erythrocyte sedimentation rate (ESR) was within normal limits. Autoimmune screening was negative and complement levels were normal. A full lung function test done essentially showed normal respiratory function, with normal spirometry, lung volumes and diffusion capacity.
A repeat CT scan, once
again showed a similar collapsed/fibrotic “triangular density” segment in the
level of the inferior lingula with evidence of an aberrant systemic arterial
supply as shown in (Figure 1). Based on the CT scan, the probable diagnosis of
BPS was given. However, the contradicting radiological finding was a possible
tracheobronchial connection, and the recommendation for a diagnostic
bronchoscopy was given.
Thoracic aortogram done
showed a hypertrophied branch of the left internal mammary artery (internal
thoracic artery) and a serpiginous artery arising from the celiac trunk of the
infra-diaphragmatic segment of the aorta. Once arising from the celiac trunk,
the serpiginous artery enters the aortic hiatus of the diaphragm, over the
dorsal surface of the diaphragm, and courses lateral to the cardiac apex to
supply the pathological inferior lingula segment of interest. A diagnostic
bronchoscopy carried out showed no tracheobronchial connection and an anatomic
narrowing of the lumen at the inferior lingula, as shown in (Figure 2).
Washings done acquired a blood tinged fluid from the lingula segment of the
left lung, and the rest of cultures, acid fast bacilli, and cytology were
unremarkable. As a result of the above findings, the diagnosis of extralobar
sequestration, a type of BPS, was given.
There are currently 4
known types of BPS. Intralobar sequestration (ILS), the most common type, is
characterized by the sequestered lobe being present within the normal lobe and
lacking its own visceral pleura. Extralobar sequestration (ELS), is where the
sequestered lobe is found outside the normal lobes of the lung and has its’ own
visceral pleura. There are other forms of ELS, such as extrathoracic ELS.
Congenital pulmonary airway malformation (CPAM), also known as hybrid BPS, is
where the malformed lesion is either an ILS or ELS and possessing unique
histological CPAM features. Lastly, bronchopulmonary foregut malformation is
where the sequestered lobe is abnormally connected to the gastrointestinal
tract, which happens during the development of the foregut, hence its’ name [1,3-5].
ILS accounts for about 75% of BPS, while ELS accounts for 25% of BPS [1,3].
The pathogenesis of BPS,
though not completely understood, has an embryological basis to many theories [2].
The clinical presentation differs in the based on the type of BPS. Half of all
adults with ILS are asymptomatic. BPS are often discovered as an incidental
finding. If symptomatic, ILS commonly presents as recurrent pneumonias due to
the absence of the visceral lining. Conversely, ELS do not present with
infections, but with rare complications such as respiratory distress,
congestive cardiac failure or spontaneous pulmonary haemorrhages. In this
instance, the cause of the episodic haemoptysis may be due to the high pressure
blood flow coming through the abnormal serpiginous artery from the abdominal
aorta during high physiological demand states e.g. stress or exercising [1].
Imaging modalities used
help to attain 2 main objectives. First to exclude other possible causes and
second to demonstrate an arterial supply from a systemic source [1,4]. On CT
scan, the sequestered lung mass may often present radiologically as a cyst
secondary to recurrent infections, dense mass, lamellar lesion, capsulated
lesion with air fluid levels, atelectatic or bronchiectatic segments [2,4]. Accompanying
emphysema are sometimes found adjacent to the sequestered lung [4]. A step
further to acquire three dimensional reconstructions from the CT scans are
often helpful. Imaging is often sufficient to make the diagnosis of BPS. Our
patient required a diagnostic bronchoscopy to further ascertain if there was a
tracheobronchial connection.
The management option for
BPS is surgical resections, that can be done either via thoracostomy or
video-assisted thoracoscopic surgery however it’s typically reserved for
symptomatic patients. A recent tertiary centre retrospective study done showed
a complication rate of 28% [3]. While another study showed no clear benefit of
surgery in asymptomatic patients [6]. Hence, the decision to surgically resect
the sequestered lobe should come down to the analysis of the risks and
benefits. Interestingly, with the rise of interventional radiology,
endovascular embolization and coiling have now emerged as possible
alternatives, by means of cutting off blood supply to the sequestered lung
leading to necrosis and resultant involution [1,6].
In summary, we present a
rare cause of haemoptysis due to an extralobar pulmonary sequestration, found
through an incidental finding in an adult female who have been relatively
asymptomatic all her life up till this point. This extralobar sequestration was
rare because of its connection to normal lung. It is difficult to determine
whether the connection between the sequestered lung and the left lower lobe was
congenital or acquired as a result of an inflammatory process. However, we
suspect that the connection was congenital A familiarity of aspects of this
rare disease should prompt one to consider its’ diagnosis when no other causes
are apparent. A combined decision by the clinician and radiologist is usually
required to make the diagnosis. The treatment decisions of BPS should be done
coordinatively with multidisciplinary team members, the patient, and their
families.