DOI:10.2214/AJR.05.0874
AJR 2007; 188:1691-1693
© American Roentgen Ray Society
Pulmonary Artery Sarcoma Mimicking Pulmonary Thromboembolism: Integrated FDG PET/CT
Semin Chong1,
Tae Sung Kim1,
Byung-Tae Kim2,
Eun Yoon Cho3 and
Jhingook Kim4
1 Department of Radiology, Samsung Medical Center, Sungkyunkwan University
School of Medicine, 50, Ilwon-dong, Gangnam-gu, Seoul 135-710, Korea.
2 Department of Nuclear Medicine, Samsung Medical Center, Sungkyunkwan
University School of Medicine, Seoul, Korea.
3 Department of Pathology, Samsung Medical Center, Sungkyunkwan University
School of Medicine, Seoul, Korea.
4 Department of Thoracic Surgery, Samsung Medical Center, Sungkyunkwan
University School of Medicine, Seoul, Korea.
Received May 23, 2005;
accepted after revision July 18, 2005.
Address correspondence to T. S. Kim.
Keywords: cardiovascular imaging • chest imaging • embolism • PET/CT • pulmonary artery sarcoma • pulmonary thromboembolism
Introduction
Pulmonary artery sarcoma is a rare malignancy arising from the mesenchymal
cells of the intima of the pulmonary artery
[1]. It is frequently
misdiagnosed as pulmonary thromboembolism, although chest CT can help
differentiate pulmonary artery sarcoma from pulmonary thromboembolism by
showing a low-attenuation filling defect occupying the entire lumen of the
proximal or main pulmonary artery, expansion of the involved arteries, or
extraluminal tumor extension
[2]. As much as the
standardized uptake values (SUVs) at 18F-FDG PET have helped in
differentiating between benign and malignant tumors
[3,
4], visualization of a
low-attenuation filling defect within a pulmonary artery on contrast-enhanced
chest CT can be suggestive of a malignancy, such as pulmonary artery sarcoma,
if the lesion shows high FDG uptake at PET. We present a case of pulmonary
artery sarcoma that showed high FDG uptake on integrated FDG PET/CT.
Case Report
A 29-year-old man with a 1-month history of medical treatment for
hemoptysis in a local hospital was referred to our institution for further
evaluation. He had no symptoms such as fever, cough, sputum, dyspnea, or
swelling of the legs.
The initial chest radiographs showed subsegmental consolidation in the
right lower lobe and a small ipsilateral pleural effusion. Contrast-enhanced
chest CT scans obtained using an MDCT scanner (LightSpeed Ultra, GE
Healthcare) after IV injection of 120 mL (3 mL/s) of nonionic contrast medium
(iopamidol [Iopamiron 300, Bracco]) showed a low-attenuation filling defect
within the lumen of the right main pulmonary artery extending to the
interlobar artery and the right lower lobar artery, raising the possibilities
of pulmonary artery thromboembolism or pulmonary artery sarcoma (Figs.
1A and
1B). Deep vein thrombosis was
not detected on indirect CT venography of the lower extremities, which had
been performed together with chest CT.
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Fig. 1A —29-year-old man with pulmonary artery sarcoma. Axial
contrast-enhanced chest CT image shows intraluminal filling defect in right
main pulmonary artery (arrows). Small ipsilateral pleural effusion is
associated with filling defect.
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Fig. 1B —29-year-old man with pulmonary artery sarcoma. Coronal
reformation image from contrast-enhanced CT shows entire extent of filling
defect from right main pulmonary artery to level of right lower lobar artery
(arrows).
|
|
To exclude the possibility of malignancy, integrated FDG PET/CT was
performed using a PET/CT device (Discovery LS, GE Healthcare) consisting of a
PET scanner (Advance NXi, GE Healthcare) and an 8-MDCT scanner (LightSpeed
Plus, GE Healthcare) approximately 45 minutes after IV injection of 370 MBq
(10 mCi) of FDG. Integrated FDG PET/CT showed increased FDG uptake along the
right main pulmonary artery and the right lower lobe pulmonary artery (maximum
SUV, 7.0), suggesting a malignant lesion (Figs.
1C and
1D).
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Fig. 1C —29-year-old man with pulmonary artery sarcoma. Axial fusion
image of integrated FDG PET/CT shows increased FDG uptake (maximum
standardized uptake value, 7.0) in right main pulmonary artery
(arrow).
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Fig. 1D —29-year-old man with pulmonary artery sarcoma. Coronal FDG
PET image shows increased FDG uptake in right main pulmonary artery
(arrows), which correlates well with areas of increased FDG uptake
seen in B (i.e., coronal CT image).
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For confirmation of the diagnosis and selection of a treatment, open
thoracotomy and excisional biopsy were performed. At surgery, frozen biopsy
specimens obtained from the right main pulmonary artery revealed a pulmonary
artery sarcoma. Finally, the patient underwent a curative right
pneumonectomy.
Grossly, a whitish-gray, myxoid, intravascular mass was found in the lumen
of the right main pulmonary artery; it extended to the segmental branches of
the lower lobe pulmonary artery, measuring 10 cm in length and 1.8 cm in
largest diameter (Fig. 1E). The
tumor showed mainly intravascular polypoid growth with focal parenchymal
invasion. Multiple areas of subsegmental hemorrhagic infarction were also seen
in the right lower lobe.
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Fig. 1E — 29-year-old man with pulmonary artery sarcoma. Photograph of
pneumonectomy specimen shows whitish-gray, myxoid, intravascular mass within
right main pulmonary artery that extends to segmental branches of lower lobe
pulmonary artery (arrows). Note multiple areas of subsegmental
hemorrhagic infarction in right lower lobe (arrowheads).
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Histopathologic examination of the intravascular mass revealed high-grade
pulmonary artery sarcoma consisting of abundant spindle cells with high
cellularity, frequent mitoses, and nuclear pleomorphism
(Fig. 1F). Neither mediastinal
nor hilar lymph node metastasis was found. The patient recovered uneventfully
and had no evidence of local recurrence or distant metastasis 1 year after
surgery.
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Fig. 1F — 29-year-old man with pulmonary artery sarcoma.
Photomicrograph of intravascular mass shows abundant spindle cells with high
cellularity, frequent mitoses, and nuclear pleomorphism; these findings are
suggestive of high-grade sarcoma. (H and E, x200)
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Discussion
During a diagnostic workup, differentiating radiologically between
pulmonary artery sarcoma and pulmonary artery thromboembolism is relatively
difficult, although chest CT findings can be specific in patients with
advanced disease and an analysis of contrast enhancement of the lesion on MRI
can help in the differential diagnosis
[5–7].
In a CT analysis for distinguishing pulmonary artery sarcoma from pulmonary
embolic disease, Yi et al. [2]
reported that CT findings favoring the diagnosis of pulmonary artery sarcoma
included a low-attenuation filling defect occupying the entire luminal
diameter of the proximal or main pulmonary artery, expansion of the involved
arteries, and extraluminal tumor extension. However, these CT findings can be
nonspecific in cases of extensive pulmonary thromboembolism. Therefore, a new
noninvasive technique for the diagnosis of pulmonary artery sarcoma is needed
to avoid a delay in diagnosis and in treatment and to prevent unnecessary
surgery.
Recently, the SUVs at FDG PET have helped to differentiate between benign
and malignant tumors [3].
According to several case reports on the cardiovascular application of FDG PET
[8,
9], blood thrombi showed
negative FDG uptake, whereas a malignant tumor, such as a cardiac sarcoma,
showed positive FDG uptake. Therefore, we can predict that a bland thrombus in
pulmonary thromboembolism would show an area of absent FDG uptake within a
pulmonary artery, whereas a malignant lesion—such as a pulmonary artery
sarcoma—would show positive FDG uptake on PET.
In our patient, the finding of a low-attenuation filling defect within a
pulmonary artery on contrast-enhanced CT could not be used to differentiate
between a bland thrombus and a pulmonary artery sarcoma. However, positive FDG
uptake within the pulmonary artery on integrated PET/CT reflected well the
malignant nature of the filling defect.
In conclusion, we report a case of pulmonary artery sarcoma that showed
positive FDG uptake on integrated FDG PET/CT. This FDG PET/CT finding can be
helpful in differentiating a pulmonary artery sarcoma from pulmonary
thromboembolism.
References
- Govender D, Pillay SV. Right pulmonary artery sarcoma.
Pathology 2001;33
: 243–245[CrossRef][Medline]
- Yi CA, Lee KS, Choe YH, Han D, Kwon OJ, Kim S. Computed tomography
in pulmonary artery sarcoma: distinguishing features from pulmonary embolic
disease. J Comput Assist Tomogr 2004;28
: 34–39[CrossRef][Medline]
- Nabi HA, Zubeldia JM. Clinical applications of (18)F-FDG in
oncology. J Nucl Med Technol 2002;30
: 3–9[Abstract/Free Full Text]
- Thurer RL, Thorsen A, Parker JA, Karp DD. FDG imaging of a
pulmonary artery sarcoma. Ann Thorac Surg2000; 70:1414
–1415[Abstract/Free Full Text]
- Cox JE, Chiles C, Aquino SL, Savage P, Oaks T. Pulmonary artery
sarcomas: a review of clinical and radiologic features. J Comput
Assist Tomogr 1997; 21:750
–755[CrossRef][Medline]
- Kacl GM, Bruder E, Pfammatter T, Follath F, Salomon F, Debatin JF.
Primary angiosarcoma of the pulmonary arteries: dynamic contrast-enhanced MRI.
J Comput Assist Tomogr 1998;22
: 687–691[CrossRef][Medline]
- Bressler EL, Nelson JM. Primary pulmonary artery sarcoma: diagnosis
with CT, MR imaging, and transthoracic needle biopsy.
AJR 1992; 159:702
–704[Free Full Text]
- Plutchok JJ, Boxt LM, Weinberger J, Fawwaz R, Sherman WH, Van
Heertum RL. Differentiation of cardiac tumor from thrombus by combined MRI and
F-18 FDG PET imaging. Clin Nucl Med 1998;23
: 324–325[CrossRef][Medline]
- Raman S, Nunez R, Oliver Wong C, Dworkin HJ. F-18 FDG positron
emission tomographic image of an aortic aneurysmal thrombus. Clin
Nucl Med 2002; 27:213
–214[CrossRef][Medline]
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Introduction
Case Report
