Pulmonary Sequestration and Intrathoracic Kidney: CT Diagnosis of a Rare Congenital Malformation with Bochdalek Hernia
When a Trauma CT Reveals an Entirely Different Story
A 22-year-old woman was evaluated after falling from a scooter. Because
the clinical question was trauma, the initial purpose of contrast-enhanced CT
was straightforward: identify fractures, hemorrhage, solid-organ injury,
vascular injury, or other acute traumatic abnormalities.
No significant traumatic injury was identified.
Yet the CT examination revealed something much more unusual.
Within the left lower lobe was an abnormal segment of lung supplied by three
systemic feeding arteries arising from the thoracic aorta. The venous
drainage was unusual, involving the hemiazygos system. At the same time, the
left kidney was not in its expected retroperitoneal position. Instead, it was
located within the thoracic cavity through a left posterolateral
diaphragmatic defect, accompanied by part of the left adrenal gland, the
gastric fundus, and the spleen.
The final imaging constellation was:
Intralobar pulmonary sequestration + intrathoracic kidney + left Bochdalek
hernia + complex systemic and renal vascular anatomy.
The case is valuable because none of these abnormalities should be
interpreted in isolation.
The diagnostic answer emerges only when the radiologist connects four
anatomical questions:
Where is the abnormal tissue?
Where does its blood supply come from?
Where are the organs located?
What happened to the diaphragm?
That approach transforms a routine trauma CT into a detailed map of
congenital anatomy.
1. The Case at a Glance
The patient was a 22-year-old woman who underwent chest, abdominal, and
pelvic CT after a scooter accident. The examination did not demonstrate
significant traumatic injury, but it revealed several congenital abnormalities.
The major CT findings were:
- Left lower-lobe intralobar
pulmonary sequestration
- Three systemic feeding
arteries arising from the thoracic aorta
- Abnormal venous drainage
toward the hemiazygos system
- Left posterolateral Bochdalek
hernia
- Left intrathoracic kidney
- Two accessory renal
arteries
- Partial herniation of the
left adrenal gland
- Herniation of the gastric
fundus
- Herniation of the spleen
- No significant acute
traumatic injury
The combination is exceptionally instructive because pulmonary
sequestration and intrathoracic kidney are individually uncommon, while their
coexistence with a Bochdalek hernia creates a much more complex developmental
anatomy.
The central lesson is simple:
Do not stop reading a trauma CT when the trauma is negative.
A normal trauma study can still contain clinically important congenital,
vascular, oncologic, or incidental findings.
2. Figure-by-Figure CT Interpretation
Figure 1. Frontal Scout View
Figure 1. Frontal scout view demonstrating an abnormal left diaphragmatic
configuration and providing the initial anatomical clue to the congenital
thoracoabdominal abnormality.
The scout image does not establish the diagnosis of pulmonary
sequestration or intrathoracic kidney by itself. Its value is more subtle.
It provides the first anatomical overview.
The radiologist should examine:
- The position and contour
of the left hemidiaphragm
- The distribution of
abdominal gas
- The lower thoracic
soft-tissue contours
- The cardiomediastinal
silhouette
- Any apparent displacement
of abdominal organs
In this patient, the scout image serves as an anatomical warning sign. A
structure that normally belongs below the diaphragm may appear unexpectedly
high, prompting careful evaluation of the subsequent cross-sectional images.
The important principle is that the scout image should not be regarded
merely as a technical positioning image. It can provide the first clue that the
anatomy is not normal.
Figure 2. Axial Contrast-Enhanced Arterial-Phase CT
Figure 2. Axial arterial-phase CT demonstrating three systemic feeding
arteries arising from the thoracic aorta and entering the abnormal left
lower-lobe pulmonary tissue, a key diagnostic feature of pulmonary
sequestration.
This is arguably the most diagnostically important image in the case.
The defining anatomical abnormality in pulmonary sequestration is not
simply an abnormal mass-like pulmonary opacity.
It is the combination of:
abnormal pulmonary tissue + absent normal bronchial communication +
systemic arterial supply.
The most important question is therefore:
Is there a systemic artery entering the abnormal basal pulmonary tissue?
In this patient, three feeding arteries arise from the
thoracic aorta.
That finding dramatically changes the differential diagnosis.
A lower-lobe opacity may initially suggest:
- Pneumonia
- Pulmonary abscess
- Atelectasis
- Bronchiectasis
- Congenital pulmonary
airway malformation
- Lung neoplasm
But once a systemic feeding artery is demonstrated, pulmonary
sequestration becomes a leading diagnosis.
Modern multidetector CT angiography is particularly valuable because it
simultaneously demonstrates the lung abnormality and the vascular anatomy
required for treatment planning.
The presence of three arteries is particularly important. A common
interpretive error is to identify one anomalous artery and stop searching.
This case demonstrates why that approach is unsafe.
The radiologist should actively search for:
- Number of feeding
arteries
- Arterial origins
- Vessel diameter
- Course
- Entry point into the
sequestered tissue
- Relationship to the aorta
and diaphragm
- Venous drainage
- Pulmonary arterial
connections
The CT therefore functions not merely as a diagnostic examination but as a
preoperative vascular roadmap.
Figure 3. Axial Contrast-Enhanced Arterial-Phase CT
Figure 3. Axial arterial-phase CT demonstrating two accessory renal
arteries arising superior to the main left renal artery and supplying the
ectopic intrathoracic left kidney.
The next diagnostic challenge is the kidney.
The left kidney is not in its expected retroperitoneal location. However,
identifying an ectopic kidney is only the beginning.
The vascular anatomy is equally important.
Two accessory renal arteries are demonstrated in addition to the principal
renal artery.
This matters because an ectopic kidney may have a variable vascular
supply. Unlike the typical kidney, whose renal artery commonly originates from
the abdominal aorta near the level of the renal hilum, an ectopic kidney may
receive arteries at unusual levels.
Consequently, before any surgical procedure, the following must be
documented:
- Main renal artery
- Accessory renal arteries
- Arterial origins
- Renal veins
- Ureteral course
- Renal parenchymal
enhancement
- Collecting-system anatomy
Missing an accessory renal artery can have direct surgical consequences.
This is why CT angiography of an intrathoracic kidney is not merely an
anatomical curiosity. It is a surgical safety study.
Figure 4. Coronal Contrast-Enhanced Arterial-Phase CT
Figure 4. Coronal arterial-phase CT demonstrating the left intrathoracic
kidney, its venous drainage, and the abnormal relationship between the kidney
and the diaphragm.
Coronal reconstruction is particularly powerful in this case.
Axial images show the anatomy slice by slice. Coronal images provide a
much clearer understanding of the superior-inferior relationship between:
- Kidney
- Diaphragm
- Thoracic cavity
- Abdominal cavity
- Herniated organs
The coronal plane also allows the radiologist to follow the renal vessels
more naturally along their longitudinal course.
For complex congenital anatomy, multiplanar interpretation should
therefore include:
Axial + Coronal + Sagittal + MPR/3D reconstruction.
Three-dimensional volume rendering can be particularly useful when
multiple anomalous arteries are present, and surgery or vascular intervention is
being considered.
Figure 5. Coronal Contrast-Enhanced Portal-Venous Phase
CT
Figure 5. Coronal portal-venous-phase CT demonstrating the left kidney
within the thoracic cavity through a left Bochdalek hernia, with associated
herniation of abdominal structures.
The key question in this image is:
Why is the kidney in the chest?
The answer is not simply “renal ectopia.”
The kidney has passed through a congenital posterolateral diaphragmatic
defect.
The associated contents include:
- Left kidney
- Part of the left adrenal
gland
- Gastric fundus
- Spleen
This establishes the anatomical relationship between intrathoracic
kidney and Bochdalek hernia.
When evaluating an ectopic kidney in the chest, the radiologist should
systematically document:
- Kidney location
- Kidney size
- Parenchymal enhancement
- Collecting system
- Renal arteries
- Renal veins
- Ureter
- Diaphragmatic defect
- Other herniated organs
The distinction between congenital and traumatic displacement is
particularly important in this case because the patient presented after a fall.
Figure 6. Sagittal Contrast-Enhanced Portal-Venous Phase
CT
Figure 6. Sagittal portal-venous-phase CT demonstrating the left
intrathoracic kidney and its direct anatomical relationship with the
posterolateral diaphragmatic defect.
Sagittal reconstruction provides the final spatial confirmation.
It demonstrates that this is not simply a “high-riding kidney.” The kidney
is genuinely located within the thoracic cavity.
This distinction is clinically important.
A high-positioned abdominal kidney, diaphragmatic eventration, congenital
thoracic kidney, Bochdalek hernia, and traumatic diaphragmatic rupture can
produce overlapping appearances.
The sagittal image helps establish the actual anatomical pathway.
3. What Is Pulmonary Sequestration?
Pulmonary sequestration, also called
bronchopulmonary sequestration, is a congenital malformation consisting of
abnormal pulmonary tissue that lacks normal communication with the
tracheobronchial tree and receives systemic arterial blood supply.
It is best understood as a developmental abnormality of the lung and its
vascular connections.
Two major forms are recognized:
Intralobar Pulmonary Sequestration
In intralobar sequestration (ILS), the abnormal lung tissue is
incorporated within an existing pulmonary lobe and shares the visceral pleural
covering.
This is the type identified in this patient.
Extralobar Pulmonary Sequestration
In extralobar sequestration (ELS), the abnormal tissue has its own
visceral pleural investment and is anatomically separate from the adjacent
normal lung.
The venous drainage pattern can help distinguish the two. Intralobar
sequestration generally drains through pulmonary veins, whereas extralobar
sequestration more commonly drains into systemic veins.
The present case is unusual because the venous drainage is described
toward the hemiazygos system, emphasizing why actual vascular anatomy should
take priority over assumptions based on textbook patterns.
4. Pathophysiology of Pulmonary Sequestration
The exact embryological mechanism remains incompletely established.
One widely accepted concept is that an abnormal accessory lung bud develops during embryogenesis. This tissue becomes separated from the normal
bronchial tree and develops an independent vascular supply.
The most clinically important abnormality is systemic arterialization.
Normal pulmonary circulation is a low-pressure vascular system. By
contrast, systemic arteries operate at substantially higher pressure.
When systemic arterial blood enters abnormal pulmonary tissue, several
consequences may occur:
- Recurrent infection
- Chronic inflammation
- Hemoptysis
- Pulmonary vascular
remodeling
- Left-to-left shunting
- Increased cardiac
workload
- Rare pulmonary
hypertension or heart failure
The high-pressure systemic arterial supply is therefore not merely an
anatomical curiosity.
It explains why pulmonary sequestration can become clinically significant
even when the patient has relatively mild respiratory symptoms.
5. Epidemiology
Pulmonary sequestration is uncommon and represents a small proportion of
congenital pulmonary malformations.
It is most frequently identified in the lower lobes, with a recognized
predominance of left-sided lesions.
The literature indicates that systemic arterial supply is the defining
imaging feature, while the number and origin of feeding arteries can vary
considerably. In a major imaging review, most aberrant arteries arose from the
descending thoracic aorta, although other origins have also been described, and
multiple supplying arteries occurred in a minority of cases.
The present patient fits the classic lower-lobe distribution but
demonstrates an unusual vascular complexity with three feeding arteries.
Pulmonary sequestration may be diagnosed:
- During childhood
- During investigation of
recurrent pneumonia
- During evaluation of
hemoptysis
- During prenatal imaging
- During CT performed for
unrelated disease
- During trauma imaging
The increasing use of multidetector CT has made incidental adult diagnosis
increasingly possible.
6. Clinical Presentation
The clinical spectrum is broad.
Some patients remain completely asymptomatic.
Others present with:
Recurrent pneumonia
Repeated infection in the same lower-lobe region should raise suspicion
for an underlying congenital pulmonary abnormality.
Chronic cough
Persistent cough may result from recurrent infection or chronic
inflammatory changes.
Hemoptysis
Hemoptysis is particularly important because abnormal systemic arterial
pressure can produce significant bleeding.
Dyspnea
Large lesions, infection, vascular shunting, or associated congenital
anomalies may contribute to respiratory symptoms.
Incidental detection
The present case belongs to the most educational category: incidental
diagnosis during trauma CT.
The patient did not undergo CT because of pulmonary symptoms.
The abnormality was discovered because the entire thoracoabdominal anatomy
was reviewed.
7. Imaging Features of Pulmonary Sequestration
A practical CT approach is to evaluate four major domains.
7.1 Location
Look for an abnormality, particularly in the lower lobe.
7.2 Parenchymal appearance
The lesion may appear as:
- Consolidation
- Solid mass-like tissue
- Cystic abnormality
- Mixed solid-cystic tissue
- Abnormal hyperlucent or
emphysematous region
7.3 Systemic arterial supply
This is the most important diagnostic feature.
The radiologist should trace the artery back to its origin.
7.4 Venous drainage
Determine whether drainage is through:
- Pulmonary veins
- Azygos system
- Hemiazygos system
- Other systemic veins
CT angiography is particularly effective because it can demonstrate both
the parenchymal lesion and its arterial and venous anatomy in one examination.
8. A Critical Modern Differential: Anomalous Systemic
Arterial Supply
A particularly important modern distinction is between true intralobar
pulmonary sequestration and anomalous systemic arterial supply to the basal
segment of otherwise normally connected lung.
These entities can look similar because both may demonstrate systemic
arterialization.
However, the bronchial and pulmonary arterial anatomy differs.
Recent work has emphasized this distinction, and a 2026 comparative study
specifically evaluated intralobar pulmonary sequestration versus anomalous
systemic arterial supply using clinical characteristics and three-dimensional
imaging.
Therefore, a systemic feeding artery should not automatically be equated
with pulmonary sequestration.
The radiologist should ask:
Is the bronchial anatomy abnormal, or is this normal lung receiving an
anomalous systemic artery?
This distinction may influence surgical strategy.
9. Intrathoracic Kidney
An intrathoracic kidney is an exceptionally rare form of renal
ectopia in which the kidney is located above the diaphragm.
It can occur as an isolated congenital anomaly or in association with
congenital diaphragmatic defects.
The present case is particularly important because the ectopic kidney is
associated with a left Bochdalek hernia.
The kidney is therefore not simply “high.”
It has a defined anatomical pathway through a diaphragmatic defect.
10. Pathophysiology of Intrathoracic Kidney
During embryogenesis, the kidneys initially develop in the pelvic region
and subsequently ascend toward their final retroperitoneal position.
Abnormal renal ascent, abnormal diaphragmatic development, or congenital
diaphragmatic herniation can result in thoracic renal ectopia.
The differential mechanism becomes particularly important after trauma.
An intrathoracic kidney can theoretically result from:
- Congenital thoracic renal
ectopia
- Congenital diaphragmatic
hernia
- Diaphragmatic eventration
- Traumatic diaphragmatic
rupture
- Acquired displacement
A published review of traumatic intrathoracic kidney specifically
emphasizes the importance of distinguishing congenital ectopia, diaphragmatic
herniation, eventration, and traumatic rupture.
This distinction is essential in trauma radiology.
A kidney found in the chest after a fall does not automatically mean
that trauma caused the kidney to move.
The radiologist must examine the morphology of the diaphragm, chronicity
indicators, associated congenital anatomy, and vascular configuration.
11. Epidemiology and Clinical Presentation of
Intrathoracic Kidney
Intrathoracic kidney is extremely rare.
Published case series have documented predominantly left-sided examples as
well as bilateral cases and associations with other congenital abnormalities.
Most patients are asymptomatic or have symptoms unrelated to the ectopic
kidney.
Possible clinical problems include:
- Hydronephrosis
- Urinary obstruction
- Recurrent urinary
infection
- Hematuria
- Renal dysfunction
- Associated diaphragmatic
abnormalities
However, the presence of a thoracic kidney does not automatically mean
that treatment is required.
A recent review of functional congenital intrathoracic kidney emphasizes
that preserved renal function is possible and that management should be
individualized according to renal function, symptoms, and associated
abnormalities.
12. Bochdalek Hernia
A Bochdalek hernia is a congenital posterolateral diaphragmatic
defect through which abdominal structures can enter the thoracic cavity.
Although classically recognized in neonates, adult Bochdalek hernia can
remain clinically silent and be discovered incidentally.
A systematic review of adult cases found that left-sided defects
predominated and that gastrointestinal and pulmonary symptoms were common among
symptomatic patients.
In this patient, the defect contains:
- Left kidney
- Part of the left adrenal
gland
- Gastric fundus
- Spleen
This pattern is highly informative because the presence of multiple
abdominal organs above the diaphragm strongly supports a congenital
diaphragmatic defect rather than a simple positional variant.
13. Differential Diagnosis
Pulmonary Differential
Pneumonia
A persistent lower-lobe opacity may mimic pulmonary sequestration.
Lung abscess
Cavitation can create a misleading appearance.
Bronchiectasis
Recurrent infections may produce chronic lower-lobe abnormalities.
Lung tumor
A focal mass in an adult should raise oncologic considerations.
However, a systemic feeding artery from the aorta dramatically shifts the
differential toward a congenital vascular-pulmonary anomaly.
Congenital pulmonary airway malformation
CPAM may overlap radiologically with pulmonary sequestration, and hybrid
lesions can occur. Modern congenital lung-malformation reviews emphasize that
multiple congenital abnormalities may coexist and that CT findings can overlap.
Diaphragmatic Differential
Diaphragmatic eventration
The diaphragm may appear elevated but remains intact.
Traumatic diaphragmatic rupture
This is particularly important after blunt trauma.
Bochdalek hernia
A true posterolateral defect with herniation of abdominal contents
supports congenital Bochdalek hernia.
Posterior mediastinal mass
An intrathoracic kidney can mimic a posterior mediastinal mass if its
vascular and collecting-system anatomy is not recognized.
14. Diagnosis: A Structured CT Strategy
A practical diagnostic sequence for this case is:
Step 1: Identify the abnormal lung tissue
Locate the lesion and characterize its morphology.
Step 2: Search for systemic arterial supply
Trace every abnormal vessel back to its origin.
Step 3: Count the feeding arteries
Never assume there is only one.
Step 4: Evaluate venous drainage
Determine whether the drainage is pulmonary or systemic.
Step 5: Search for associated congenital abnormalities
Examine the diaphragm, mediastinum, abdomen, and genitourinary tract.
Step 6: Locate both kidneys
If one kidney is absent from its expected location, actively search the
thorax.
Step 7: Map renal vasculature
Identify main and accessory renal arteries and renal veins.
Step 8: Evaluate the diaphragm
Determine whether there is a congenital defect, eventration, or traumatic
rupture.
Step 9: Perform multiplanar and 3D reconstruction
Use axial, coronal, sagittal, MPR, and—when appropriate—volume-rendered
images.
This structured strategy follows the anatomical logic demonstrated by the
present case.
15. Treatment
Pulmonary Sequestration
Management depends on symptoms, lesion anatomy, systemic arterial supply,
venous drainage, associated abnormalities, and procedural risk.
Potential approaches include:
- Surgical resection
- Lobectomy
- Sequesterectomy in
selected lesions
- Endovascular embolization
- Selected surveillance
strategies in carefully chosen asymptomatic patients
Surgical resection remains a well-established approach for symptomatic
pulmonary sequestration, while endovascular techniques have also been used in
selected situations.
The three feeding arteries in this patient are particularly important for
operative planning.
If one vessel is missed, residual systemic perfusion may remain.
Intrathoracic Kidney
A functionally normal asymptomatic congenital intrathoracic kidney does
not necessarily require repositioning.
Treatment becomes more relevant when there is:
- Renal dysfunction
- Urinary obstruction
- Hydronephrosis
- Recurrent infection
- Symptomatic hernia
- Organ compression
- Other clinically
significant complications
Published cases of Bochdalek hernia with functionally normal ectopic
kidneys demonstrate that the kidney can sometimes be safely left in its
thoracic position while repairing the diaphragmatic defect.
The decision should therefore be individualized rather than based solely
on the kidney's unusual location.
16. Prognosis
The prognosis of pulmonary sequestration is generally favorable when
appropriately recognized and managed.
Potential complications of untreated symptomatic disease include:
- Recurrent infection
- Hemoptysis
- Chronic inflammation
- Cardiopulmonary effects
from systemic shunting
- Rare severe vascular
complications
For intrathoracic kidney, preserved renal function is compatible with an
excellent long-term outcome in many patients.
The long-term prognosis depends more on:
- Renal function
- Urinary drainage
- Infection
- Vascular anatomy
- Associated congenital
anomalies
than on the thoracic position alone.
Adult Bochdalek hernia has a more variable prognosis because acute
complications such as obstruction, strangulation, or respiratory compromise can
occur. In the adult systematic review, surgical management was common, particularly
when symptoms or complications were present.
17. How Artificial Intelligence Could Change Diagnosis
Artificial intelligence is becoming increasingly important in CT
interpretation, but an important distinction must be made.
There is currently no sufficiently validated, disease-specific AI
system that should independently diagnose pulmonary sequestration,
intrathoracic kidney, and Bochdalek hernia as a complete syndrome.
Therefore, it would be inappropriate to claim that a commercial AI
algorithm can currently replace expert interpretation of this rare combination.
However, modern medical AI can support the diagnostic workflow in several
highly relevant ways.
17.1 Automated Thoracic Segmentation
Deep-learning algorithms can segment:
- Lungs
- Aorta
- Pulmonary arteries
- Pulmonary veins
- Kidneys
- Diaphragm
- Abdominal organs
This creates an anatomical framework within which unusual relationships
can be detected.
17.2 Vessel Tracking
One of the most promising applications is automated vascular-tree
analysis.
An AI system could trace an artery from the thoracic aorta and identify
whether it enters an abnormal basal pulmonary segment.
For this case, such a system could potentially generate:
Aorta → Feeding artery 1 → Sequestered lung
Aorta → Feeding artery 2 → Sequestered lung
Aorta → Feeding artery 3 → Sequestered lung
The key benefit would be reducing the risk of overlooking a second or
third feeding vessel.
17.3 Automated Kidney Localization
An AI system can potentially compare expected and observed organ
locations.
If the left renal fossa is empty while a kidney-like structure is detected
above the diaphragm, an automated alert could be generated:
“Left kidney not identified in expected location—evaluate thorax for
ectopic kidney.”
This is conceptually different from a simple disease classifier. It is an anatomical
anomaly detection system.
17.4 Multiplanar 3D Reconstruction
AI-assisted segmentation could automatically generate a 3D vascular
roadmap showing:
- Feeding arteries
- Renal arteries
- Renal veins
- Aorta
- Diaphragmatic defect
- Herniated organs
Such a model could become particularly useful for surgical planning.
Recent work has also highlighted the clinical value of 3D imaging in
differentiating intralobar pulmonary sequestration from anomalous systemic
arterial supply to the basal segment.
17.5 Explainable AI
For rare congenital disease, an AI system should not simply output:
“Pulmonary sequestration: 94%.”
A clinically useful system should show why.
For example:
Detected abnormal basal lung tissue
Detected systemic artery from descending thoracic aorta
Three arterial branches identified
Normal pulmonary arterial connection not demonstrated
Left kidney absent from renal fossa
Renal tissue detected superior to diaphragm
Posterolateral diaphragmatic defect detected
This type of explainable output would be much more clinically meaningful.
18. AI and Treatment Planning
The most realistic near-term role of AI may not be autonomous diagnosis.
It may be preoperative anatomical intelligence.
For this patient, an AI-assisted planning system could automatically produce
a surgical map containing:
Pulmonary system
- Location of sequestration
- Volume of abnormal tissue
- Three systemic feeding
arteries
- Vessel diameters
- Arterial origins
- Venous drainage
Renal system
- Main renal artery
- Two accessory renal
arteries
- Renal vein
- Ureter
- Renal parenchymal volume
Diaphragm
- Defect size
- Defect location
- Relationship to aorta
- Herniated organs
This would allow surgeons, interventional radiologists, and radiologists
to work from the same three-dimensional anatomical model.
The emerging paradigm is therefore not:
AI replaces the radiologist.
It is:
AI reconstructs complex anatomy; the radiologist validates it; the
multidisciplinary team uses it for clinical decision-making.
19. Imaging Checklist for Daily Practice
|
Domain |
What to Check |
|
Lung |
Location and morphology of
abnormal tissue |
|
Systemic artery |
Origin and course |
|
Feeding arteries |
Number and diameter |
|
Venous drainage |
Pulmonary or systemic |
|
Pulmonary artery |
Normal connection present or
absent |
|
Diaphragm |
Defect, eventration, or
rupture |
|
Kidney |
Position, size, enhancement |
|
Renal arteries |
Main and accessory arteries |
|
Renal veins |
Number and drainage |
|
Ureter |
Course and continuity |
|
Hernia contents |
Kidney, adrenal, stomach,
spleen, bowel |
|
Trauma |
Fracture, hematoma, organ
injury |
|
3D reconstruction |
Preoperative vascular
roadmap |
This structured approach is consistent with the central lesson of the
case: anatomy should be interpreted as a connected system rather than as
isolated abnormalities.
20. Seven Things Every Radiologist Should Remember
1. A lower-lobe mass is not always a tumor.
Look for a systemic feeding artery.
2. A systemic artery can be the diagnostic key.
Trace it to its origin.
3. Never assume there is only one feeding artery.
This patient had three.
4. If a kidney is missing from the renal fossa, search the thorax.
Do not stop at the abdomen.
5. Always inspect the renal vessels.
Ectopic kidneys frequently have variant vascular anatomy.
6. After trauma, do not automatically label an intrathoracic kidney as
traumatic.
Congenital diaphragmatic hernia can explain the finding.
7. Do not interpret complex congenital anatomy on axial images alone.
Use axial, coronal, sagittal, MPR, and 3D reconstruction.
21. Why This Case Matters Beyond a Rare Diagnosis
The most important finding in this patient is not any single abnormality.
It is the relationship among the abnormalities.
The lung abnormality is connected to the systemic arterial circulation.
The kidney is connected to the diaphragm.
The diaphragm is connected to the thoracoabdominal transition.
The renal position is associated with abnormal renal vessels.
The hernia contains several abdominal organs.
In other words, the CT tells an embryological story.
This is one of the most important skills in modern radiology:
Recognize anatomical relationships rather than simply naming individual
abnormalities.
A radiologist who sees only “left lower-lobe opacity” may miss pulmonary
sequestration.
A radiologist who sees only “left kidney absent” may miss an intrathoracic
kidney.
A radiologist who sees only “elevated left hemidiaphragm” may miss a
Bochdalek hernia.
But a radiologist who connects:
abnormal lung → systemic artery → abnormal kidney position → diaphragmatic
defect → herniated abdominal organs
can recognize the entire congenital syndrome.
Quiz
Question 1
A 22-year-old woman undergoes CT after a scooter accident. The CT
demonstrates abnormal tissue in the left lower lobe supplied by three arteries
arising from the thoracic aorta.
What is the most likely diagnosis?
A. Pneumonia
B. Pulmonary embolism
C. Pulmonary sequestration
D. Bronchiectasis
E. Lung cancer
Correct answer: C. Pulmonary sequestration
Explanation
The defining imaging clue is systemic arterial supply to abnormal
pulmonary tissue. The presence of three feeding arteries arising from the
thoracic aorta strongly supports pulmonary sequestration.
Question 2
CT demonstrates that the left kidney is located within the thoracic cavity
through a posterolateral diaphragmatic defect. The gastric fundus and spleen
are also partially herniated.
What is the most appropriate diagnosis?
A. Renal tumor
B. Renal dislocation
C. Intrathoracic kidney associated with Bochdalek hernia
D. Pyelonephritis
E. Horseshoe kidney
Correct answer: C. Intrathoracic kidney associated with Bochdalek hernia
Explanation
A posterolateral diaphragmatic defect with transdiaphragmatic herniation of
abdominal organs is characteristic of Bochdalek hernia. In this case, the left
kidney is one of the herniated structures.
Question 3
What is the most important preoperative CT angiography information in a
patient with suspected pulmonary sequestration?
A. Gallbladder position
B. Spleen size
C. Systemic feeding arteries and venous drainage
D. Colon length
E. Ureteral diameter alone
Correct answer: C. Systemic feeding arteries and venous drainage
Explanation
The anomalous systemic arterial supply is central to diagnosis and
treatment planning. Importantly, more than one feeding artery may exist, as
demonstrated by the three arteries in this case.
Final Take-Home Message
Recommended Reading
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[7] S. Sabharwal, B. Young, S. Sabharwal, et al.,
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