AJR 2003; 180:1617-1619
© American Roentgen Ray Society
Regression of Abdominal Visceral Aneurysms in Polyarteritis Nodosa: CT Findings
N. Cagla Tarhan1,
Mehmet Coskun1,
Esra M. Kayahan1,
Erkan Yildirim1 and
Eftal Yucel2
1 Department of Radiology, Baskent University Hospital, Fevzi Cakmak Cad. 10.
Sok No: 45, 06490 Bahçelievler, Ankara, Turkey.
2 Department of Rheumatology, Baskent University Hospital, 06490
Bahçelievler, Ankara, Turkey.
Received June 28, 2002;
accepted after revision October 30, 2002.
Address correspondence to N. C. Tarhan.
Introduction
Polyarteritis nodosa is a rare systemic necrotizing vasculitis that affects
small and medium-sized arteries
[1,
2]. Gastrointestinal
involvement is most common and occurs in up to 50% of patients
[2]. The kidneys, heart, liver,
pancreas, muscles, spleen, central nervous system, and skin are other sites
that may be affected [3]. The
lesions include aneurysmal sacs that are 1–5 mm in diameter, stenosis or
occlusion of vessels, and intraparenchymal infarction
[3]. The aneurysms may rupture,
and this rupture is most often observed in renal and mesenteric vessels
[4]. Early diagnosis of
polyarteritis nodosa is important for prognosis. Reports have documented
regression of associated aneurysms after combined medical treatment with
steroids and immunosuppressant drugs
[5]. To date, angiography has
been required to detect the small aneurysmal dilatations
[4]. We describe a case of
polyarteritis nodosa in which multidetector CT (MDCT) revealed small intact
aneurysms of the hepatic, gastroduodenal, and pancreaticoduodenal arteries and
intraparenchymal hematomas caused by spontaneous rupture. Follow-up with the
same imaging method showed disappearance of the aneurysms after medical
treatment.
Case Report
A 58-year-old man who had recently been diagnosed with necrotizing
vasculitis due to polyarteritis nodosa at another medical center was referred
to our hospital for further evaluation. At the other hospital, the initial
workup on sonography and single-detector CT revealed multiple hematomas and
intraparenchymal infarcts in the liver parenchyma, and hepatic and renal
angiography showed multiple aneurysms of the hepatic, gastroduodenal,
pancreaticoduodenal, and renal arteries. At abdominal surgery, subcapsular
hematomas in the right lobe of the liver, ischemic areas in the right and left
hepatic lobes, and numerous intraperitoneal hematomas, particularly in the
perihepatic space, were seen. In addition, gangrenous appendicitis was
diagnosed. A liver biopsy was obtained, and pathologic examination revealed
necrotizing vasculitis.
On admission to our hospital, the patient's presenting complaints were
persistent crampy abdominal pain, fever, and pain and numbness in both legs.
Findings at physical examination were unremarkable. The laboratory findings
were as follows: WBC, 12.6 x 109/L (normal range,
4.5–11.0 x 109/L) with polymorphonuclear leukocytes
predominant; erythrocyte sedimentation rate, 80 mm/hr (normal range,
0–20 mm/hr); C-reactive protein, alkaline phosphatase, and
-glutamyl-transferase levels were also elevated. Findings of serologic
tests for hepatitis B antigen and antibody were negative, and results of
testing for autoimmune disease revealed no abnormal findings.
MDCT on a Volume Zoom scanner (Siemens, Erlangen, Germany) was performed
before IV contrast administration and during the arterial, portal, and delayed
phases after contrast injection. Five-millimeter-thick slices were obtained.
The arterial phase images showed multiple strongly enhanced nodular structures
in various segments of the liver, with the highest number in the central part
of the medial segment of the left lobe (Figs.
1A and
1B). These lesions were
consistent with irregular aneurysmal dilatations of the hepatic artery, and
their diameters ranged from 3 mm (Fig.
1A) to 2 cm (Fig.
1B). We also noted a strongly enhanced nodular structure adjacent
to the head of the pancreas that measured 12 x 7 mm, interpreted as an
aneurysm of the gastroduodenal artery (Fig.
1C). A similar nodular lesion in the pancreatic parenchyma
measured 10 x 5 mm, consistent with aneurysm of the posterior
pancreaticoduodenal arcade
(Fig.1D). The liver contained
the most lesions. All MDCT findings were confirmed by comparing them with
recent angiograms from the other medical center.
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Fig. 1A. —58-year-old man with polyarteritis nodosa. Contrast-enhanced
arterial phase axial multidetector CT (MDCT) image shows multiple aneurysms in
liver parenchyma. Smallest aneurysm has diameter of 3 mm (arrow).
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Fig. 1B. —58-year-old man with polyarteritis nodosa. Contrast-enhanced
arterial phase axial MDCT image at level higher than that of A shows
largest aneurysm measuring 2 cm in diameter (arrow). In addition to
these lesions, two large hypodense nodular lesions in liver parenchyma are
seen consistent with hematoma or hemorrhagic infarct.
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Fig. 1C. —58-year-old man with polyarteritis nodosa. Contrast-enhanced
arterial phase axial MDCT image at level lower than that of A shows
aneurysmal dilatation of gastroduodenal artery (arrow).
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Fig. 1D. —58-year-old man with polyarteritis nodosa. Contrast-enhanced
arterial phase axial MDCT image at level higher than that of C shows
aneurysmal dilatation of pancreaticoduodenal arcade (arrow). Small
nodular hyperdense lesion in left kidney is consistent with acute
hematoma.
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In addition to the aneurysms, MDCT showed multiple nodular lesions in the
liver parenchyma. These were relatively hyperdense on unenhanced images and
were thought to be either intraparenchymal hematomas caused by spontaneous
aneurysm rupture or hemorrhagic necrosis from thrombosis. There was a 3.5
x 2.5 cm hypodense cystic lesion with smooth contours in the uncinate
process of the pancreas. The unenhanced series also showed a 1-cm-diameter
hyperdense nodular lesion at the superior pole of the left kidney that did not
enhance with contrast administration (Fig.
1D). These latter two lesions were interpreted as intraparenchymal
hematomas, and the renal one was identified as the most recent. The patient
was diagnosed with polyarteritis nodosa on the basis of clinical and imaging
findings and was prescribed a combination of corticosteroid (oral prednisone,
1 g/kg of body weight per day) and immunosuppressive treatment
(cyclophosphamide, 500 mg IV). Follow-up abdominal MDCT performed 5 months
after the patient was first admitted to our center showed significant
regression of all the aneurysms that we had detected previously in the liver
(Fig. 1E), pancreas
(Fig. 1F), or kidney. The
lesions in the liver and pancreas were also reduced.
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Fig. 1E. —58-year-old man with polyarteritis nodosa. Five months later,
follow-up contrast-enhanced arterial phase MDCT images show that aneurysms
previously detected in liver are no longer present (E), pancreatic
aneurysms also are not present (F), and hypodense liver lesions are
decreased (arrow, F) in image obtained at level lower than
that of E.
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Fig. 1F. —58-year-old man with polyarteritis nodosa. Five months later,
follow-up contrast-enhanced arterial phase MDCT images show that aneurysms
previously detected in liver are no longer present (E), pancreatic
aneurysms also are not present (F), and hypodense liver lesions are
decreased (arrow, F) in image obtained at level lower than
that of E.
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Discussion
In the acute stage of systemic necrotizing vasculitis known as
polyarteritis nodosa, pathologic examination reveals fibrinous exudation,
fibrinoid necrosis, and polymorphonuclear cell infiltration of all layers of
the arterial wall. Subsequently, the necrotic lesions granulate, and intimal
proliferation leads to thrombosis, infarction, and aneurysm formation
[6].
Angiography is considered the gold standard for diagnosis. The main
angiographic findings in polyarteritis nodosa are small aneurysms, vascular
ectasia, and occlusive vascular disease manifesting as luminal irregularity,
stenosis, or occlusion of small and medium-sized arteries of the viscera
[7]. These abnormalities are
detected in 40–90% of patients who have just developed clinical
symptoms. Our patient had multiorgan involvement with hepatic, pancreatic, and
renal aneurysms. Using recent technical advances in CT, we could detect
extremely small aneurysms of the hepatic artery. To date, it has not been
possible to show this size of aneurysm with cross-sectional imaging. The
arterial phase images in our patient clearly showed hepatic aneurysms as small
as 3 mm. Affected individuals who are diagnosed early respond particularly
well to steroid and immunosuppressive treatment and tend to have better
prognoses [5,
8]. Our patient showed good
response to treatment in that all the aneurysms that had been detected in the
hepatic, gastroduodenal, pancreaticoduodenal, and renal arteries disappeared.
This change was shown clearly on follow-up abdominal CT at 5 months.
Darras-Joly et al. [8]
suggested that angiography should not be performed in patients with
polyarteritis nodosa who show clinical improvement because of the invasiveness
of this procedure. We also believed that repeated angiography was not
necessary in our patient and opted to follow up with the noninvasive MDCT
imaging instead. In previous work, Holzknecht et al.
[2] and Wilms et al.
[4] used cross-sectional
imaging techniques to show intraparenchymal arterial aneurysms in
polyarteritis nodosa patients but did not mention the sizes of the aneurysms
they detected. Very small aneurysms in patients with polyarteritis nodosa
cannot be visualized on single-detector CT
[3]; however, we could show
aneurysms as small as 3 mm in diameter. Precise timing of the arterial bolus
of contrast material and the use of MDCT yielded excellent diagnostic
information. To our knowledge, this is the first report that has shown CT
visualization of the disappearance of aneurysms during follow-up in a patient
with polyarteritis nodosa.
In summary, we describe a case of polyarteritis nodosa in which MDCT showed
aneurysms of the hepatic, pancreatic, and renal arteries and lesions inside
these organs caused by either aneurysm rupture or thrombosis. MDCT also
confirmed excellent response to immunosuppressive treatment. MDCT can be used
as a noninvasive imaging technique for diagnosing small aneurysms in patients
with suspected polyarteritis nodosa and for following up these patients after
treatment.
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Introduction
Case Report
