AJR 2000; 174:229-233
© American Roentgen Ray Society
Hepatic Pulmonary Fusion in Neonates
Thomas L. Slovis1,
Diana L. Farmer2,
Walter E. Berdon3,
Raja Rabah4,
John B. Campbell5 and
Arvin I. Philippart2
1
Department of Pediatric Imaging, Children's Hospital of Michigan, 3901
Beaubien Blvd., Detroit, MI 48201.
2
Department of Pediatric Surgery, Children's Hospital of Michigan, Detroit, MI
48201.
3
Department of Radiology, Babies and Children's Hospital of New York, 3975
Broadway, Rm. 3-318, New York, NY 10032.
4
Department of Pathology, Children's Hospital of Michigan, Detroit, MI
48201.
5
Department of Radiology, Arnold Palmer Hospital for Children and Women, 92 W.
Miller St., Orlando, FL 32806.
Received February 1, 1999;
accepted after revision June 29, 1999.
Address correspondence to T. L. Slovis.
Abstract
OBJECTIVE. This report discusses the relationship of
supradiaphragmatic hepatic tissue that is fused to the lung (through a
diaphragmatic defect) with pulmonary hypoplasia—a new constellation of
findings.
CONCLUSION. Hepatic pulmonary fusion should be suspected in
instances of apparent diaphragmatic hernia characterized by mediastinal shift
towards the hypoplastic lung or when the mediastinum does not shift away from
the mass.
Introduction
Hepatic tissue located above the diaphragm in the thoracic cavity
occurs in three situations: a congenital diaphragmatic hernia with significant
liver volume in the chest creating mass effect; ectopic supradiaphragmatic
liver nodules unattached or barely attached via a pedicle to the main body of
the liver in the abdomen; and the connection of the liver and lung by a tight
fibrous band or interspersion of a portion of supradiaphragmatic liver and
lung (hepatic pulmonary fusion)
[1,
2]. In each scenario, the
rationale for surgery is different as is the scope of the procedure. We
describe six patients in whom hepatic pulmonary fusion was diagnosed and
present radiographic clues that help to distinguish anomalies.
Materials and Methods
A computerized search was performed using the clinical and pathologic
records of three tertiary care children's hospitals. The search for records of
hepatic pulmonary fusion covered a time span of 25 years. All images used in
this study were reviewed by three pediatric radiologists.
Results
We found six records describing patients with hepatic pulmonary fusion,
right-sided lesions, and diaphragmatic defects
(Table 1 and
Figs. 1,
2,
3A,
3B,
4A,
4B,
5A,
5B,
5C). All patients were
neonates, four girls and two boys. After reviewing the records, we found five
instances of right-sided pulmonary hypoplasia (defined radiographically in
four patients and pathologically in one patient), five instances of systemic
arterial and venous circulation to the fused lung (seen at surgery), two
instances of left-sided congenital heart disease, and two instances of
sequestrations. Two patients in this series died, one from hypoplastic left
heart syndrome and one from uncertain causes immediately after surgery.
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Fig. 1. —4-day-old boy with hepatic pulmonary fusion and moderate respiratory
distress. Frontal chest radiograph shows right shift of mediastinum, minimal
liver opacity in abdomen, and mass within right hemithorax. Right lung is
hypoplastic.
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Fig. 2. —2-day-old girl with hepatic pulmonary fusion and respiratory
distress. Frontal chest radiograph shows hypoplasia of right lung and mass
within right hemithorax. Mediastinum has not shifted. Note liver is seen in
abdomen.
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Fig. 3. —1-day-old boy with hepatic pulmonary fusion and mild
retractions.
A, Frontal chest radiograph shows small posterior paraspinal mass on
right side (arrow). Small mass has not affected mediastinal
position.
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Fig. 4. —6-hour-old girl with hepatic pulmonary fusion and severe respiratory
distress.
A, Frontal chest radiograph shows large mass in right chest (right
diaphragmatic hernia). Mediastinum shifted away from lesion; image does not
show reason for fusion.
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Fig. 4. —6-hour-old girl with hepatic pulmonary fusion and severe respiratory
distress.
B, Histology of postmortem specimen reveals lung in upper field in
continuity with liver in lower field. Membranous tissue separates lung and
liver (arrowheads) with no pleura or liver capsule.
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Fig. 5. —1-day-old girl with hepatic pulmonary fusion and mild retractions of
intercostal muscles.
A, Frontal chest radiograph shows two masses in right hemithorax
(arrow on smaller mass) with small shift of mediastinum.
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Fig. 5. —1-day-old girl with hepatic pulmonary fusion and mild retractions of
intercostal muscles.
B, Follow-up frontal chest radiograph (at 5 weeks old) reveals liver
almost filling right hemithorax with mediastinal shift away from lesion.
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Fig. 5. —1-day-old girl with hepatic pulmonary fusion and mild retractions of
intercostal muscles.
C, Histology reveals nodule of liver (arrowheads) embedded
in lung tissue (sequestration). Fused lung-liver interface was separated but
not resected.
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Imaging showed a mediastinal shift toward the hepatic pulmonary fusion in
four patients, and no mediastinal shift in one patient in whom the mass was
very small. One patient's images showed a mediastinal shift away from the
fusion, a large right-sided diaphragmatic hernia, and the entire liver located
in the right chest. One patient's images initially showed a mediastinal shift
toward the hypoplastic lung, but on a second imaging the entire liver
herniated through the defect and caused a contralateral shift.
Surgeons found fusion of the liver and lung in all patients; the liver and
lung were able to be separated and the diaphragm repaired in four patients. In
two patients, resection or mobilization of the liver was not accomplished;
surgeons were concerned that during correction the hepatic veins, inferior
vena cava, and the systemic vascularization of the fused lung would be
obstructed. In one of these patients the diaphragmatic defect was partially
repaired. Two patients' lungs were described as "trapped within leaves
of the diaphragm" and "encased in a semifibrous adhesive capsule
consistent with an accessory diaphragm"; however, these suggestions of
an accessory hemidiaphragm were not confirmed by histopathology.
We obtained pathology reports for four patients. Histologic evaluation
revealed these four patients had thick-walled arteries and veins with healthy
alveoli and large bronchi in the lung. Their livers showed a healthy portal
area and bile ducts. For three patients, a delicate fibrous membrane separated
the lung from the liver tissue. Also, there was no liver capsule, pleura, or
diaphragm.
Discussion
Supradiaphragmatic hepatic tissue either isolated or attached to the
normally positioned liver is rare
[1,
2]. Of the seven cases in the
literature of which we are aware, two neonates had lethal left-sided
congenital heart disease [1,
2]. The fusion of ectopic
hepatic tissue to other organs such as the gallbladder, adrenal gland, spleen,
or gonad has been reported, but hepatic pulmonary fusion is virtually unknown
[3]. When hepatic pulmonary
fusion occurs in a neonate with signs of respiratory distress, it can create a
diagnostic and therapeutic dilemma.
A large chest opacity in a neonate with respiratory distress will have mass
effect—a mediastinal shift away from the lesion and compression of the
left lung. The most common lesions are congenital diaphragmatic hernias,
congenital cystic adenomatoid malformations, and large bronchopulmonary
foregut malformations [4,
5,
6]. However, when a large
opacity is not associated with mass effect, concomitant pulmonary hypoplasia
must be considered, and the differential diagnosis of the mass includes a
smaller sequestration or congenital cystic adenomatoid malformation and tumor
such as neuroblastoma.
A large chest opacity without mass effect or pulmonary hypoplasia of the
affected side is extremely rare
[7,
8]. The absence of mass effect
(mediastinal shift, compression of the contralateral lung, and depressed
contralateral diaphragm) in images that show a chest opacity should be
considered an indication that an unusual lesion such as hepatic pulmonary
fusion may be present. In this setting, the goal of surgery is to restore the
separate integrity of the thoracic and abdominal cavities, a procedure that
may require segmental pulmonary resection to separate the fused lung and liver
tissue. This procedure allows restoration of negative intrathoracic pressure,
may improve pulmonary growth in the involved lung, and eliminates the
possibility of increasing liver penetration in the thoracic cavity.
The cause of hepatic pulmonary fusion is open to conjecture. During
gestational weeks 4-6, the liver, lung, and diaphragm form in close
continuity. Some have suggested that whenever hepatic tissue is found in the
thoracic cavity, the hepatic diverticulum grows in the septum transversum
(precursor to the central tendon of the diaphragm), and a portion of the liver
is pinched off and may end up in the pleuroperitoneal canal
[1,
2,
9,
10]. At the same time, the
lung buds grow in each pericardioperitoneal canal
[11]. Each
pericardioperitoneal canal is then divided by a cranial pleuropericardial
membrane and an inferior pleuroperitoneal membrane with the developing lungs
located between them. The forming diaphragm is partially composed of the
pleuroperitoneal membranes (other components include the septum transversum,
the dorsal mesentery of the esophagus, and the body wall). The exact reason
for hepatic pulmonary fusion is unknown and, in fact, "the etiology and
mechanism of genesis of a diaphragmatic hernia are not known. The most logical
explanation is failure to fuse rather than failure to form."
[9] The failure to fuse the
diaphragmatic membranes may allow the fusion of adjacent future pulmonary and
hepatic tissue.
The explanation of the association of hepatic pulmonary fusion with
left-sided cardiac anomalies is unknown, but the hepatic diverticulum, septum
transversum, and aorticopulmonary septum all form in close proximity during
gestational weeks 4-6.
The occurrence of hypoplasia of the right lung and systemic arterial and
venous circulation in the fused lung suggests a relationship to congenital
pulmonary venolobar syndrome. Pulmonary sequestration may be associated with
traditional diaphragmatic hernia
[4,
5,
6,
7,
8]. However, to our knowledge,
in neither entity has fusion of the liver and lung been described. Though
surgeons noted the possibility of accessory diaphragm in two of our patients,
diaphragmatic tissue was not found in pathologic specimens.
Except for a case report of fibrous fusion between the liver and lung
[3], the closest examples to
our patients are the three children with defects of the diaphragm and healthy
liver herniated in the chest accompanied by anomalous systemic circulation to
the right lower lobe of the lung
[12]. These patients' lungs
had healthy bronchial connections and no separation from the main portion of
lung. Macpherson and Whytehead
[12] called this
"pseudosequestration syndrome." However, in one case, the
description suggested the liver was "adherent to the right lower
lobe." [12]
Our six patients showed a spectrum of conditions from fusion of a portion
of lung with the main component of the liver to fusion of a portion of lung
with an ectopic suprahepatic nodule of liver that connected to the main
component of the liver by a pedicle. The fusion may be a fibrous connection or
true interspersion of the liver and lung tissue.
Hepatic pulmonary fusion cannot be diagnosed using imaging alone, but it
can be suggested when a mass and hypoplasia of the lung coexist without
mediastinal shift. When this complex is associated with left-sided congenital
heart lesions, the possibility of hepatic pulmonary fusion should be
considered.
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Abstract
Introduction
