AJR 2002; 179:805
© American Roentgen Ray Society
Infected Intralobar Bronchopulmonary Sequestration Mimicking Lung Neoplasm on CT and Positron Emission Tomography
Vincent C.-Y. Chan,
Phillip M. Boiselle,
Adolf W. Karchmer and
Robert L. Thurer
Beth Israel Deaconess Medical Center, and Harvard Medical School,
Boston. MA 02215
The combined use of CT and positron emission tomography (PET) with FDG
typically allows accurate differentiation of benign and malignant nodules.
Exceptions do occur, and in this report, we describe one such example. To our
knowledge, ours is the first report of an infected sequestration mimicking a
lung neoplasm on CT and PET.
A 54-year-old man had been in good health until approximately 1 year before
undergoing an evaluation of pain and induration in the lower right chest. He
was treated empirically with antibiotics, but his symptoms did not completely
resolve. CT showed soft-tissue thickening and erosion of the right eighth rib.
A 1.5-cm lobulated, spiculated nodule without cavitation or calcification was
also noted in the right lower lobe, distant from the site of chest wall
inflammation (Fig. 5A). Because
of persistent symptoms, the patient underwent a partial rib resection with a
pathologically based diagnosis of osteomyelitis. However, results from
bacterial cultures and fungal stains from the bone were negative.
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Fig. 5A. —54-year-old man with chest wall infection and an incidentally
detected focal opacity in right lower lobe of lung. Magnification of CT scan
shows focal opacity (arrow) in right lower lobe with lobulated and
spiculated margins.
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The patient had a persistent sinus track in his chest so follow-up CT was
performed 6 months later. CT revealed postoperative changes in the right chest
wall and a slight enlargement of the nodule in the right lower lobe. A
coincident FDG PET study showed a focus of modest glycolytic activity at the
site of the osteomyelitis. An area of intense uptake was also identified in
the right lower lobe (Fig. 5B).
Acting on the basis of the CT and PET findings, surgeons resected the lesion.
At surgery, an area of consolidated lung tissue with cystic spaces filled with
purulent material was found. A feeding vessel originating from the aorta was
also identified. The features were consistent with an infected intralobar
sequestration. Cultures from the surgical specimen revealed Aspergillus
fumigatus.
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Fig. 5B. —54-year-old man with chest wall infection and an incidentally
detected focal opacity in right lower lobe of lung. Axial positron emission
tomographic image shows focus of intense FDG uptake in right lower lobe
corresponding to lesion (long and short arrows) seen on CT.
Physiologic left ventricular activity (LV) and bone marrow activity in spine
(V) are shown.
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An intralobar sequestration is a pulmonary malformation with no
communication with the tracheobronchial tree that is supplied by systemic
arterial circulation and is contiguous with normal lung parenchyma. Intralobar
sequestration is postulated to arise after an infection
[1]. On CT, it usually presents
as a focal homogeneous or heterogeneous opacity and is located most commonly
in the posterior basal segment of the left lower lobe. The sensitivity and
specificity for CT in detecting a malignant spiculated pulmonary nodule are
reported to be 87% and 45%, respectively
[2]. The sensitivity and
specificity of FDG PET for differentiating malignant from benign solitary
pulmonary nodules are reported to be 93% and 88%, respectively
[3]. Although FDG PET has a
higher specificity than does CT, FDG PET has the limitation of producing
false-positive results in patients with infections and inflammation. A few
case reports of Aspergillus organisms colonizing an intralobar
sequestration have been previously described
[4]. Careful pathologic
assessment of the resected lesion is necessary because squamous cell
carcinomas and adenocarcinomas have been reported to arise within
sequestrations.
This case underscores the importance of considering sequestration as part
of the differential diagnosis of a lesion in the posterior basal segment of
the lower lobe of the lung. It also underscores the fact that a subclinical
infection can result in increased glycolytic activity on an FDG PET study,
thus mimicking a neoplastic process.
References
- Frazier AA, Rosado de Christenson ML, Stocker JT, Templeton PA.
Intralobar sequestration: radiologic-pathologic correlation.
RadioGraphics
1997;17:725
-745[Abstract]
- Zwirewich CV, Vedal S, Miller RR, Muller NL. Solitary pulmonary
nodule: high-resolution CT and radiologic—pathologic correlation.
Radiology
1991;179:469
-476[Abstract/Free Full Text]
- Gupta NC, Maloof J, Gunel E. Probability of malignancy in solitary
pulmonary nodules using fluorine-18-FDG and PET. J Nucl
Med 1996;37:943
-948[Abstract/Free Full Text]
- Freixinet J, de Cos JD, Rodriguez de Castro F, Julia G, Romero T.
Colonisation with Aspergillus of an intralobar pulmonary
sequestration. Thorax
1995;50:810
-811[Abstract/Free Full Text]
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