Extralobar Pulmonary Sequestration with Heterotopic Hepatic Tissue 

 

Article by

G.V. Kulkarni

T.A. Baker

P. Sojitra

C.H. Wigfield

 

Abstract

Supradiaphragmatic benign hepatic tissue has been very rarely reported in literature. Paucity of data with comparative images have made this diagnosis a difficult one. We report a case of extralobar intrathoracic pulmonary sequestration as seen in an adult male, containing heterotopic liver tissue. This case presented with a history of recurrent pneumonias that had remained refractory to antibiotic therapy.

 

Introduction:

There are less than twenty cases of supradiaphragmatic benign hepatic tissue that have been reported in medical literature. The first case was described in 1957 by Hansborough and Lipin[1] Ectopic liver tissue within intrapulmonary sequestrations do occur although infrequently in the pediatric population and is sporadic among adult patients.[2,3] It is difficult to make an accurate diagnosis  preoperatively  as  there  is  a paucity of  data  and  comparative  images  available.  An isolated supradiaphragmatic hepatic lobule is an infrequent finding unless associated with prior operative trauma. We report an adult case of extralobar intrathoracic pulmonary sequestration containing heterotopic liver tissue presenting with recurrent pneumonia refractory to antibiotic therapy.

 

Case Report:

A   31-year-old   man   presented   to   a   tertiary thoracic surgery center with a long history of recurrent chest infections requiring multiple hospital admissions since childhood. Recent episodes of pneumonia that had been treated with antibiotics were associated with progressive dyspnea. The patient experienced shortness of breath, initially on exertion and subsequently, even at rest.

Numerous computed tomography (CT) scans at different hospitalizations suggested a likely right lower lobar pulmonary sequestration with abnormal vascular supply. Also associated with his condition was right-sided lung hypoplasia which was presumed to be congenital. Despite completed courses of antibiotics he failed to respond completely, eventually requiring almost immediate re-admission for more intensive therapy multiple times. He was referred to our center for surgical evaluation for the same. No other thoracic abnormalities were found on clinical or radiologic examination.

His preoperative pulmonary function tests showed a mild obstructive defect, responsive to bronchodilators with normal gas diffusion pattern. Review of axial cross-sectional CT imaging did not show clear evidence of a heterogeneous lesion in the right lower lobe. An iso-dense lobar lesion with an aberrant blood supply was noted (Figure 1). Informed consent was obtained, and a resection was performed. Bronchoscopy on induction demonstrated hyperemic changes in the distal right-sided mediobasal segment and bronchoalveolar lavage showed no suspicious cytology or pathogen growth. Patient was maintained on oral antibiotics prior to surgery in view of his clinical presentation and previously suspected sequestration.

A right anterolateral latissimus-muscle-sparing thoracotomy through  the fifth intercostal space was performed. Mobilization and resection of the suspected pulmonary sequestration was uneventful  with   deliberate   identification  and

TC- Apr 2018 - 001 - Coronal reformatted CT scan of chest

ligation of the aberrant vasculature. Margins of the tissue resected included a wedge resection of right lower lobe parenchyma surrounding the aberrant tissue.

Operative findings included considerable pleural adhesions presumed to be associated with the recurrent infections. A partial decortication was therefore required to gain adequate access to the right lower lobe. Three sizable arterial feeding vessels to the right lower lobe were isolated and separately ligated and then divided between curved staplers with vascular load. Two venous branches draining independently from the lobar venous branches were attached to a 3 x 4 cm intralobar mass in the right lower lung parenchyma and appeared firm and encapsulated. During the dissection, it was essentially enucleated from the right lower lobar lung tissue. The stalk of the mass was directed to the medial aspect and appeared attached to the diaphragm. The mass with the stalk was sent for frozen section and permanent pathology.

Intraoperative frozen section was reported to be consistent with normal benign hepatic parenchyma, microscopically consisting of cords of large, polygonal hepatic cells, and bile ducts. No pathologic hepatic features were present. A small   diaphragmatic   defect   present  after  the resection of the stalk was repaired using bioabsorbable extra cellular matrix (Comatrix) to provide a regenerative repair. No separate hepatic ducts were identifiable, and no post resection bile leak was noted. Prior to closure, a triple antibiotic solution was used for a thorough washout of the right chest. There was evidence of ipsilateral pulmonary hypoplasia.

His postoperative course was uneventful. He was seen in clinic for several postoperative visits and he remained symptom-free with no recurrence of any pulmonary infections. The final pathology confirmed the diagnosis of “benign liver parenchyma”. Once the anomaly was resected, it appeared to significantly improve patient’s pulmonary status with no effect on hepatic function.

 

Discussion

Pulmonary sequestrations are rare congenital abnormalities of the thoracic cavity, incident in less than 1% of the general population.[4] Two forms of pulmonary sequestration are described; intralobar (more common and present in 75-5% of cases) and extralobar (rare entity).

The occurence of extra-hepatic heterotopia is  also uncommon. It can be supradiaphragmatic within the thoracic cavity, in association with such pulmonary sequestration and is extremely rare with less than 20 cases described in medical literature.[5,6] More commonly heterotopic liver tissue predominantly occurs intra-abdominally, occurring in the vicinity of the gall bladder, pancreas, spleen omentum, adrenals, with usually some mesenteric attachments to the liver.[7] Among the very limited number of cases of intra-thoracic liver tissue, several were diagnosed only at autopsy. Even within the thoracic cavity it is more likely for the hepatic tissue to be attached to the liver through the diaphragm.[6,8] The radiographic appearance is not specific, and a differential diagnosis is difficult with imaging alone.

Most of the cases of symptomatic intralobar sequestrations are seen in pediatric population.[2,6] Despite recurrent respiratory infections since childhood, there had been no surgical management for this patient. A definitive pathological diagnosis and conclusive management of such anomalies is possible only after resection. The occurrence of supradiaphragmatic liver lobules in the presence of an intact diaphragm and absence of any other thoracic anomalies has not been described to our knowledge, hence it would be difficult to predict the natural course of such aberrant tissue.

In this case, it appeared to be functioning as normal hepatic tissue and hepatic enzymes secreted into the sequestration cavity possibly contributed to incite an inflammatory reaction in addition to the recurrent pulmonary infections, which has been long considered the hallmark in the natural course of sequestration anomalies.

Considering this to be the first case which documents this as a solitary developmental anomaly, it raises questions regarding possible embryologic explanations of the origins of this abnormality. The most probable is the possibility of an accessory liver lobule developing from the fetal hepatic bud followed by atrophy or regression of the connection that existed to the remainder of the hepatic development in sub diaphragmatic loco typico. Alternatively, a singular and separate liver bud develops without any connection with the primary hepatic bud at any stage of development.[3]

Two studies in the pediatric population describing the multiple facets of pulmonary sequestration, show it to be an uncommon occurrence. These anomalies were incidental findings during autopsy for less than 10% of cases  when  it  was  coexistent  with  hydrops  fetalis  or  pulmonary  hypoplasia  which was the  eventual cause of death. Pulmonary sequestrations were asymptomatic at presentation in roughly 10% cases and were not resected.  Radiologic   embolization   of   feeding vessels   was   performed  in  one  case.  All  cases eventually had symptomatic complications of respiratory infections, asthma and gastroesophageal reflux disease.[9,10]

 

Conclusions

Supra-diaphragmatic heterotopia of hepatic tissue is extremely rare and its association with pulmonary sequestrations is even less widely known. In the presence of an unclear diagnosis and suspicious imaging, this needs to be considered under the appropriate clinical setting. Definitive treatment of this anomaly is surgical resection when symptomatic. Accurate histological diagnosis can only be obtained on pathological examination post resection.

 

Disclosures: The authors of this article have nothing to disclose.

Conflict of Interest: Extra Cell Matrix for repair of diaphragmatic defect post resection in the chest, has been utilized in this case which has not yet been approved as an indication for this product.

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References:

 

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