INTERESTING IMAGE
Carcinoma of the Lung Misinterpreted as Pulmonary
Sequestration on Contrast CT But Correctly Identified on FDG
PET/CT
Bi-Fang Lee, MD, PhD,* Han-Yu Chang, MD,† Jing-Jou Yan, MD,‡ Nan-Tsing Chiu, MD,*
and Yau-Lin Tseng, MD, PhD§
Abstract: The chest x-ray of a 68-year-old man with a history of cough with
blood-tinged sputum showed an abnormality in the right lower lung. Contrast-enhanced CT favored pulmonary sequestration with a feeding artery
from the right inferior phrenic artery and a drainage vein into the right
pulmonary vein. He had shortness of breath and chest tightness, which
prompted an FDG PET/CT study to evaluate the nature of the mass. The
images revealed abnormal FDG accumulation in a right lower lung mass and
a mediastinal lymph node. Therefore, a possible diagnosis of lung carcinoma
with mediastinal lymph node metastasis was suggested. A right lower lobe
lobectomy was performed. Histopathologically, squamous cell carcinoma
with mediastinal lymph node metastases was diagnosed (stage IIIA by
AJCC, T2N2).
Key Words: squamous cell carcinoma, pulmonary sequestration, FDG,
PET/CT
(Clin Nucl Med 2010;35: 343–345)
REFERENCES
1. Okamoto T, Masuya D, Nakashima T, et al. Successful treatment for lung
cancer associated with pulmonary sequestration. Ann Thorac Surg. 2005;80:
2344 –2346.
Received for publication December 4, 2009; revision accepted December 9, 2009.
From the Departments of *Nuclear Medicine, †Internal Medicine, ‡Pathology,
and §Surgery, National Cheng Kung University, College of Medicine and
Hospital, Tainan, Taiwan.
Reprints: Yau-Lin Tseng, MD, PhD, Thoracic division, Department of Surgery,
National Cheng Kung University Hospital, 138 Sheng-Li Road, Tainan City
70428, Taiwan. E-mail: [email protected].
Copyright © 2010 by Lippincott Williams & Wilkins
ISSN: 0363-9762/10/3505-0343
Clinical Nuclear Medicine • Volume 35, Number 5, May 2010
2. Su MG, Fan QP, Fan CZ, et al. Lung sequestration and pott disease
masquerading as primary lung cancer with bone metastases on FDG PET/CT.
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of pulmonary nodules with an initial standard uptake value less than 2.5. Am J
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Lee et al
Clinical Nuclear Medicine • Volume 35, Number 5, May 2010
FIGURE 1. A 68-year-old man complained of cough with blood-tinged sputum for a long time. Recently, he had shortness of
breath and chest tightness. Contrast CT of the thorax revealed the arterial supply from both the right pulmonary (arrow) and
right inferior phrenic artery (arrow head) and venous drainage into the right inferior pulmonary vein with no obvious interval
change as compared with the previous study 1 month ago, which was a pathognomonic feature of pulmonary sequestration.1– 8
An intralobar sequestration is a congenital bronchopulmonary malformation with no communication with the tracheobronchial tree
that is supplied by the systemic arterial circulation and is contiguous with normal lung parenchyma. On CT, it usually presents as a
focal opacity and is located most commonly in the posterior basal segment of the lower lobe. The principal objective for diagnosis
of pulmonary sequestration is to identify the systemic artery supply. With this information, CT can distinguish sequestration from
other causes of lung opacity. We have performed 3-dimensional reconstruction segmentation for a better understanding of the
anatomy of the abnormal systemic arteries. Based on these findings, the possibility of pulmonary sequestration was raised.
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Clinical Nuclear Medicine • Volume 35, Number 5, May 2010
Lung Carcinoma Correctly Identified on FDG PET/CT
FIGURE 2. FDG PET/CT was performed after the patient fasted for 6 hours before receiving an intravenous injection of 370
MBq (10 mCi) of FDG. He stayed calmly in the supine position for 1 hour after radionuclide administration. An integrated
PET/CT scanner (Biograph, Siemens Medical Solutions) was used to acquire images from the head to the upper part of the
thighs. Delayed images of the suspected pulmonary foci were obtained 2 hours after FDG injection. The images were reconstructed with a standard ordered-subset expectation maximization algorithm. The axial spatial resolution was 4 mm at the
center of the field of view. For drawing regions of interest, transverse, coronal, sagittal, and maximum-intensity-projection PET
and CT images were acquired 1 hour and 2 hours after FDG injection and were displayed simultaneously on a monitor with
the same window and level. The CT images were set in the lung window setting. The region of interest was drawn in the
midportion of the pulmonary lesion with the highest radioactivity, and its margin was approximately 70% of the maximal radioactivity. PET/CT showed abnormal FDG uptake to a RLL mass (maximum standardized uptake values 关SUVmax兴 of 12.37
关1 hour兴, 13.99 关2 hours兴) (arrow) and a mediastinal lymph node (SUVmax of 3.87 关1 hour兴, 4.95 关2 hours兴) (arrow head).
Knowing the findings from the PET/CT, lung carcinoma with mediastinal lymph node metastasis was diagnosed. A right lower
lobe lobectomy was performed and pathologic examination revealed squamous cell carcinoma (SCC) with mediastinal lymph
node metastases.
A previous report concerned FDG PET/CT findings of pulmonary sequestration, in which no abnormal FDG accumulated.1 Infectious or inflammatory processes in pulmonary sequestration can result in significantly increased FDG activity.2,3 FDG
PET/CT is generally regarded as being useful in detecting lung cancer with metastases.9,10 In our case, SCC and a mediastinal
lymph node with higher FDG accumulation in the delayed phase was consistent with the notion that malignancies tend to
show higher SUV accumulation in the delayed phase than in the early phase.9,10 Like our present case, if the lesions are PETpositive, the surgical resection should be performed.
Our case is interesting in several aspects. First, as a CT scan with contrast medium finds a lung mass supplied by a
highly suspicious feeding artery arising from the descending aorta, pulmonary sequestration is generally considered.1– 8 This
case underscores the importance of considering lung cancer as part of the differential diagnosis of a lesion in the posterior
basal segment of the lower lobe of the lung. Second, it is well known that a lung nodule and mediastinal lymph nodes have
significant FDG uptake on PET/CT and are frequently interpreted as a single type of malignancy with metastases.9,10 Third, it
has been well published that intralobar sequestration appears as an ill-defined firm area admixed with white and viable tumorous lesions with focal necrosis histopathologically.4 However, in our case, pathologic findings demonstrate the presence of
SCC without sequestration. At surgery, transpleural abdominal systemic artery–pulmonary artery anastomosis from the abdominal systemic artery supply was demonstrated. Systemic-to-pulmonary artery anastomoses exist in many conditions, including congenital abnormalities, acquired states, and postsurgical states.11,12 Because the patient had complaints related to
the respiratory system for years, infectious or inflammatory processes resulted in anomalous collateral systemic-pulmonary circulation. In conclusion, FDG PET/CT was useful in detecting primary and metastatic lesions of lung cancer which masqueraded as pulmonary sequestration from our presented case.
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