DOI:10.2214/AJR.05.1389
AJR 2007; 188:345-347
© American Roentgen Ray Society
Thoracic Periaortic Fibrosis Mimicking Malignant Tumor: CT and 18F-FDG PET Findings
Young Kyung Lee1,2,
Joon Beom Seo1,
Song Soo Kim1,3 and
Tae-Hwan Lim1
1 Department of Radiology, Asan Medical Center, University of Ulsan College of
Medicine, Research Institute of Radiology, 388-1, Pungnap-dong, Songpa-gu,
Seoul 138-736, Korea.
2 Present address: Division of Cardiothoracic Radiology, Department of
Radiology, Bundang CHA Hospital, University of Pocheon Jungmoon College of
Medicine, Kyonggi-do, Korea.
3 Present address: Department of Radiology, Chungnam National University
Hospital, Daejeon, Korea.
Received August 10, 2005;
accepted after revision December 7, 2005.
Address correspondence to J. B. Seo
(seojb{at}amc.seoul.kr).
Keywords: aorta • chest imaging • CT • periaortic fibrosis • PET
Introduction
Periaortic fibrosis, more commonly known as retroperitoneal
fibrosis, is an uncommon disease that was first described in 1905 by Albaran
[1] and further documented by
Ormond in 1948 [2]. It is
characterized by the progressive proliferation of connective tissue in the
retroperitoneal space, specifically along the aorta
[3,
4].
To our knowledge, ours is the first report in the English-language
literature describing the CT and 18F-FDG PET findings of periaortic
fibrosis with isolated involvement of the thoracic aorta. In this article, we
describe the CT and FDG PET findings of an unusual case of periaortic fibrosis
around the descending thoracic aorta. Intense FDG uptake on PET scans caused a
false diagnosis of malignant tumor.
Case Report
A 33-year-old man was referred to our hospital for the evaluation of back
pain of 3 months' duration. He had no history of hypertension or diabetes
mellitus and no family history of the malignancy or of trauma. Laboratory
tests showed no specific abnormal findings.
Contrast-enhanced CT, performed from the level of the thoracic inlet to the
level of the femoral head, showed an encircling soft-tissue mass surrounding
the descending thoracic aorta. The mass contained no focal area of low
attenuation to suggest necrosis or degeneration (Figs.
1A and
1B). Mild narrowing of the
aortic segment encircled by the mass was noted. Tubular enhancing structures
in the periaortic mass were seen that were thought to be traversing
intercostal arteries. No evidence of lymph node enlargement or any other mass
was found in the thorax or abdomen.
View larger version (60K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 1A —33-year-old man with periaortic fibrosis in chest. Axial
contrast-enhanced CT scan shows encircling soft-tissue mass surrounding lower
thoracic aorta and having homogeneous enhancement. Tubular lesions, suggestive
of intercostal arteries, are identified inside periaortic mass.
|
|
View larger version (127K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 1B —33-year-old man with periaortic fibrosis in chest. Sagittal
contrast-enhanced CT scan shows longish mass surrounding lower thoracic aorta.
Image is not centered on aorta, which artifactually makes it appear that aorta
is narrowed.
|
|
The differential diagnosis included periaortic lymphoma, periaortic
fibrosis, and inflammatory pseudotumor. FDG PET revealed intense FDG
accumulation, with a measured maximal standardized uptake value of 4.6 in the
corresponding mass (Fig. 1C).
The diagnosis based on FDG PET was a malignant tumor such as a lymphoma.
Excision biopsy was performed. Microscopic examination of the tumor
revealed tangled spindle cells with eosinophilic cytoplasm by H and E staining
(Fig. 1D). No invasion of the
vessels was seen. The final pathology diagnosis was periaortic fibrosis. The
patient's postoperative period was uneventful, and he was discharged and
started steroid therapy. Although the patient's symptoms were relieved after
steroid therapy, no interval change had occurred in the size and extent of the
mass on follow-up CT performed 3 months later.
View larger version (170K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 1D —33-year-old man with periaortic fibrosis in chest. Microscopic
examination of tumor reveals tangled spindle cells with eosinophilic
cytoplasm. No invasion of vessels is seen. (H and E)
|
|
Discussion
Recently, the CT finding of extensive periaortic fibrosis involving both
the descending thoracic aorta and the abdominal aorta in a patient was
reported [5]. In that report,
involvement of the thoracic aorta was easily diagnosed because the lesion was
contiguous to typical retroperitoneal fibrosis. Szarf and Bluemke
[6] reported a case of
intrathoracic periaortic fibrosis as part of a multifocal fibrosclerosis and
mediastinitis. Our case is unique in that there was no evidence of
mediastinitis, and periaortic fibrosis is located around the descending
thoracic aorta. Isolated intrathoracic involvement of periaortic fibrosis made
it difficult to exclude the possibility of a tumor.
Periaortic fibrosis is characterized by the periaortic deposition of
collagen. Its most common location is the retroperitoneum. Periaortic fibrosis
is commonly known as retroperitoneal fibrosis. Retroperitoneal periaortic
fibrosis, also known as Ormond disease, is a relatively rare disease, with an
estimated incidence of one in 200,000 people
[7]. Its peak incidence is in
patients 40-60 years old and it occurs mostly in men
[8]. Although exposure to ergot
derivative drugs, malignancy, radiation, aneurysm, trauma, and inflammatory
disorders such as pancreatitis are possible causes, about two thirds of cases
are idiopathic [7].
Although diverse techniques may contribute to evaluate patients with
retroperitoneal periaortic fibrosis, CT is the preferred imaging method. The
characteristic CT finding of retroperitoneal periaortic fibrosis is a
homogeneous mass enveloping the aorta and ureters
[9]. The CT findings in our
patient were similar to those of retroperitoneal periaortic fibrosis in
previous reports. Feinstein et al.
[10] attempted to
differentiate retroperitoneal periaortic fibrosis from lymphoma or metastatic
disease, which presents a nodular appearance. Retroperitoneal periaortic
fibrosis was manifested as a plaquelike or infiltrating pattern. In our
experience, it is difficult to distinguish between retroperitoneal periaortic
fibrosis and lymphoma or metastasis only on the basis of CT findings.
PET using FDG has been shown to be a highly sensitive diagnostic tool to
stage, restage, and monitor the progress of various neoplasms. However, a
number of physiologic and nonneoplastic conditions may also be associated with
the focal accumulation of FDG and can cause false-positive results. Chander et
al. [11] reported the PET
finding of retroperitoneal periaortic fibrosis in one patient. The intense FDG
accumulation of retroperitoneal periaortic fibrosis can cause a misdiagnosis
of malignancy. In our patient, periaortic fibrosis revealed intense
accumulation of FDG on PET.
Biopsy specimens of retroperitoneal periaortic fibrosis reveal densely
fibrotic areas of collagen and cellular inflammation
[12]. The absence of mass
effect in retroperitoneal periaortic fibrosis is expected, given the
retractile nature of the fibrotic process. Although pathologically
retroperitoneal periaortic fibrosis represents fibrosis, it takes on the
appearance of a mass [9].
Steroid therapy is effective for treating early-stage retroperitoneal
periaortic fibrosis, as are other drugs such as cyclosporine, cytotoxic
agents, and tamoxifen [7]. Our
patient started steroid therapy. After 3 months, follow-up CT showed the
periaortic mass had no significant interval change.
In summary, we report a rare case of pathologically confirmed periaortic
fibrosis encasing the descending thoracic aorta and presenting as a periaortic
mass on CT. Periaortic fibrosis shows intense accumulation of FDG on PET, and
this finding may be falsely interpreted as a malignant tumor.
References
- Albaran J. Retention renal per petriureterite: liberation externa
de l'uretere. Ass Fr Urol 1905;9
: 511-515
- Ormond J. Bilateral ureteral obstruction due to envelopment and
compression by an inflammatory retroperitoneal process. J
Urol 1948; 59:1072
-1079[Medline]
- Demko TM, Diamond JR, Groff J. Obstructive nephropathy as a result
of retroperitoneal fibrosis: a review of its pathogenesis and associations.
J Am Soc Nephrol 1997;8
: 684-688[Abstract]
- Gilkeson GS, Allen NB. Retroperitoneal fibrosis: a true connective
tissue disease. Rheum Dis Clin North Am1996; 22:23
-38[CrossRef][Medline]
- Amiya E, Ishizaka N, Watanabe A, et al. Retroperitoneal fibrosis
with periaortic and pericardial involvement. Circ J2005; 69:760
-762[CrossRef][Medline]
- Szarf G, Bluemke DA. Case 83: multifocal fibrosclerosis with
mediastinal-retroperitoneal involvement. Radiology2005; 235:829
-832[Free Full Text]
- Takashima T, Onoda N, Ishikawa T, et al. Tumorforming idiopathic
retroperitoneal fibrosis: report of a case. Surg Today2004; 34:374
-378[CrossRef][Medline]
- Meier P, Gilabert C, Burnier M, Blanc E. Retroperitoneal fibrosis,
an unrecognized inflammatory disease: clinical observations and review of the
literature [in French]. Nephrologie 2003;24
: 173-180[Medline]
- Degesys GE, Dunnick NR, Silverman PM, Cohan RH, Illescas FF,
Castagno A. Retroperitoneal fibrosis: use of CT in distinguishing among
possible causes. AJR 1986;146
: 57-60[Abstract/Free Full Text]
- Feinstein RS, Gatewood OMB, Goldman SM, Copeland B, Walsh PC,
Siegelman SS. Computerized tomography in the diagnosis of retroperitoneal
fibrosis. AJR 1981;126
: 255-259
- Chander S, Ergun EL, Chugani HT, et al. High
2-deoxy-2-[18F]fluoro-D-glucose accumulation in a case of retroperitoneal
fibrosis following resection of carcinoid tumor. Mol Imaging
Biol 2002; 4:363
-368[CrossRef][Medline]
- Lepor H, Walsh PC. Idiopathic retroperitoneal fibrosis.
J Urol 1979; 122:1
-6[Medline]
CiteULike 
Complore 
Connotea 
Del.icio.us 
Digg 
Reddit 
Technorati What's this?
Top
Introduction
Case Report
