Clinical Case Nº5

A 24 years-old man arrives to emergency department complaining dyspnea, fever, coughing blood, astenia, pleuritic pain on the left chest. A Chest X-ray is taken inmediately (image). The leucocyte counting revealed 21.300 cells, with neutrophilia. PaO2  69 mmhg. After 3 days of continues antibiotic treatment with: oral cephalosporins, azytromicin and levofloxacine, the patient stills with the same symptoms. A Broncoscopy is performed without any results.

¿What is the Diagnose?

INTRALOBAR PULMONARY SEQUESTRATION

Intralobar pulmonary sequestration is an uncommon but distinct  

clinical  entity that  may  be  the  unrecognized

cause of  recurrent pulmonary infections. The term seques-

tration,  derived  from the Latin verb sequestrure,  “to sepa-

rate,”  was  coined  by  Pryce  in  1946  [l] after his  clear

description  established intralobar  sequestration as a  dis-

tinct  clinical  entity.  Generally  regarded  to result from

disturbed  embryogenesis,  a sequestration is encountered

in 1% to 2% of  all pulmonary  resections  [2]. This malfor-

mation  is  characterized by cystic  nonfunctioning  lung

tissue that usually has no communication with the normal

bronchial tree and that receives its blood supply from an

anomalous  systemic artery. The sequestration consists of

normal  lung  elements  in  an  abnormal  and  disorderly

arrangement  with  variable cartilage, bronchial glands,

a n d  alveolar parenchyma. One or more mucus-filled cysts

result  from  mucous  secretion  into  dilated, obstructed

bronchioles  and alveoli,  causing compression aletectasis

of  surrounding parenchyma  (Fig 1). Microscopic commu-

nications with adjacent normal lung allow air and, some-

times, bacteria to enter the cysts.  If  infection is superim-

posed,  the  cysts  may  contain  purulent  material.  In  the

usual case there is extensive acute and chronic organizing

inflammation, usually  so severe that  little normal tissue

remains. Occasionally there is only a single large cyst or a

noncystic mass containing branching bronchi that  run in

the  direction  of  the aberrent  artery. Apparently  it  takes

years for these changes to occur, because the disease only

rarely becomes apparent in early infancy.

Two types  of  pulmonary sequestration exist: an intra-

lobar sequestration, in which the abnormal tissue is partly

surrounded  by  normal  lung  and  contained within  the

visceral pleura, and less commonly, an extralobar type, in

which  the  abnormal  lung  tissue  has  its  own  distinct

pleural  investment  and  maintains complete anatomical

and  physiological  separation  from  the  adjacent normal

lung.

Several theories have  attempted  in the past to explain

the embryology of  pulmonary sequestration  [l, 31.  How-

ever, they  failed to  offer a common  pathogenesis  to the

multitude of  different clinical presentations. The presence

of  communications  between the  intestinal tract  and  se-

questrations led Gerle and associates [4] to the  develop-

ment  of  a  unified  theory  of  formation  of  intralobar  and

extralobar sequestrations. This theory,  supported  by the

pathohistological studies of  Iwai and co-workers [5], pro-

poses that an additional or accessory lung bud develops in

the early embryo from the ventral aspect of  the primitive

foregut distal to the site of  formation  of  the normal lung

bud.  The accessory lung  bud  migrates  caudad  with  the

normally developing  lung and  receives its blood  supply

from the embryonic splanchnic plexus, which has numer-

ous connections to the primitive dorsal aorta. The vascu-

lar  connections  to the  dorsal aorta persist  and  form the

anomalous arterial  supply  of  the  developing  pulmonary

sequestration.

The time at which the accessory lung bud  develops in

the embryo determines whether the resulting malforma-

tion will be intralobar or extralobar. The  fact that  only a

few sequestrations maintain a patent connection with the

esophagus  or stomach may be  explained by  inadequate mass. 

Special interest in this malformation first arose in

blood  supply to the communication resulting in its invo-

lution  [4]. Simultaneously occurring intralobar and extra-

lobar pulmonary sequestrations in which the lesions were

noted to be communicating with the gastrointestinal tract

strongly support the common origin theory [6]. Albrecht-

sen [7j reported  on  a patient with  an  extralobar pulmo-

nary sequestration connected  by  a  narrow  lung  tissue

pedicle  to  the  left  lower  lobe. This case  represents  a

definite intermediate link between intralobar and extralo-

bar sequestration,  suggesting these lesions are intimately

related in etiology and pathogenesis.  With regard to the

multitude of  anatomical variations, intralobar and extra-

lobar sequestrations represent part of  a spectrum of  mal-

formations, designated “bronchopulmonary-foregut  mal-

formations” by Gerle and associates [4]. At one end of  the

spectrum is a n  anomalous arterial supply to normal lung.

At the other end of  the spectrum is abnormal pulmonary

tissue  but without anomalous  arterial supply; namely,

bronchogenic cyst, lobar emphysema, and adenomatoid

malformation. Between these two extremes lie the  vari-

ants of  sequestration. Recently Rodgers and  co-workers

[8] have suggested that the term bronchopulmonary-foregut

malformation  is best reserved  for  those abnormalities of

ventral foregut budding directly involving the pulmonary

parenchyma and originating from either the tracheobron-

chial  tree  or the  gastrointestinal tract, such  as  bron-

chogenic cysts, sequestrations,  and tracheal lobes. They

did not include lobar emphysema and cystic adenomatoid

malformations, which involve local aberrations of  paren-

chymal development.

The  presenting  complaint in  the  majority  of  patients

harboring  a  sequestration  is  either repeated  localized

pulmonary  infections  or  an  asymptomatic intrathoracic

1940 when Harris and Lewis [9] reported operative injury

of  an anomalous artery to a lower lobe, resulting in the

child’s death. Although death due  to operative trauma to

an anomalous artery has subsequently been reported [2],

most  studies have  shown that  pulmonary sequestration

can  be  diagnosed accurately before operation  and  that

surgical resection can usually be carried out safely. This

paper summarizes our clinical experience with  the  diag-

nosis and  management  of  intralobar  sequestration, em-

phasizing the unfortunate delay in diagnosis often accom-

panying this malformation.

Charatecteristics and diferential Diagnose

The position of a lesion and its persistence in a relatively young individual raises the index of suspicion that the underlying pathology may be the result of a sequestered segment. Demonstration of a dominant feeding vessel, usually from the aorta or its major vessels, and venous drainage to the pulmonary veins suggests the diagnosis.

Alternative venous drainage patterns in ILS include a route directly into the left atrium via the azygos or hemiazygos systems, into intercostals veins, or into the inferior vena cava (IVC) or superior vena cava (SVC).

The finding of alternative venous drainage patterns separates pulmonary sequestration from other diagnoses, such as infection and tumor, round atelectasis, Bochdalek hernia, and pulmonary infarction. Enlargement of the associated abnormal feeding vessels is a constant feature, and the azygos vein is also frequently enlarged.

Multiple supply arteries are found in 15% of sequestrations; 73% of sequestrations develop blood vessels leading off the abdominal aorta, and 18% develop blood vessels leading off the thoracic aorta. Rare documented origins include the ascending aorta and the arch, subclavian, innominate, celiac, right coronary, and circumflex arteries.

Extralobar sequestration

In ELS, 80% of sequestrations lie between the lower lobe and the diaphragm. Lesions are usually located in the region of the posterior basal segments of the lower lobes. Left-sided lesions are more common than right-sided lesions. The mass may be closely associated with the esophagus, and fistulae may develop.

Subdiaphragmatic ELS lesions can mimic masses arising in various organs, such as the adrenal gland. In addition, ELS frequently is associated with other congenital extrapulmonary anomalies. Venous drainage occurs via the systemic circulation.

Many patients with ELS present in infancy with respiratory distress and chronic cough; some lesions are diagnosed coincidentally.

Intralobar sequestration

In ILS, sequestrations occur within pulmonary visceral pleurae and do not communicate with the bronchial tree. ILS is seen in males and females in equal numbers. The lesions of ILS may be solid, fluid, or hemorrhagic or may contain mucus. Cystic or emphysematous elements may be present, and adjacent atelectasis often exists.

Most lesions appear hypervascular, because of abundant systemic vascularization. Super-added infection may lead to some consolidation in adjacent segments, and a chronic inflammatory process may induce localized reactive neovascularization. Mucoid impaction of a bronchus surrounded by a hyperinflated lung is believed to be characteristic of ILS.

Intrapulmonary sequestration is usually diagnosed later than ELS, being found in childhood or adulthood when the patient presents with an infection

Radiography

Conventional chest radiographic findings vary depending on the size of the lesion and whether the lesion is infected. Other factors that cause abnormal radiographic findings are the presence or absence of communication with an airway or contiguous lung tissue and the presence of associated anomalies

An uninfected sequestration is seen as a well-defined mass or, less commonly, as a cyst in the medial aspect of a posterior lung base. An infected sequestration tends to appear ill defined, may be associated with a parapneumonic effusion, and may contain one or more fluid levels.

Occasionally in ELS, a small bump may be seen on the hemidiaphragm or the inferior paravertebral region.

Rarely, a large sequestration may present with an opaque hemithorax, with or without ipsilateral effusion.

With a barium/contrast swallow study, communication between the GI tract and a sequestrated lung segment has been described and may be demonstrated by means of a contrast-enhanced examination of the esophagus.

Mass effect is demonstrated on bronchography as displacement of terminal bronchi by the sequestration. Contrast-agent filling of the sequestered segment in intralobar lesions is uncommon, even when air-fluid levels are present within the cyst. In some patients, a blind intermediate portion of right bronchus may be seen because of hypoplasia of the middle and lower lobes in ELS. CT scans can demonstrate the lack of bronchi entering a sequestration

Angiography

The blood supply of 75% of pulmonary sequestrations is derived from the thoracic or abdominal aorta. The remaining 25% of sequestrations receive their blood flow from the subclavian, intercostal, pulmonary, pericardiophrenic, innominate, internal mammary, celiac, splenic, or renal arteries. The arterial supply typically enters the lung via the pulmonary ligament if the artery originates above the diaphragm. Arteries originating below the diaphragm reach the sequestration by piercing the diaphragm or via the aortic or esophageal hiatus.

In the rare instance of sequestration in an upper lobe, arterial supply from the internal thoracic artery has been reported. If aortography (seen in the images below) is unrevealing, a coronary source should be included in the preoperative search

 References

- Medscape

- Intralobar sequestration: a missed diagnose. The annals of thoracic Surgery