AJR 2004; 183:415-419
© American Roentgen Ray Society
Gastrointestinal Stromal Tumors of the Duodenum: CT and Barium Study Findings
Hyo-Cheol Kim1,
Jeong Min Lee1,
Kyu Ri Son1,
Se Hyung Kim1,
Kyoung Ho Lee1,
Kyoung Won Kim2,
Minjin Lee3,
Joon Koo Han1 and
Byung Ihn Choi1
1 Department of Radiology, Seoul National University College of Medicine,
Institute of Radiation Medicine, Seoul National University Medical Research
Center, and Clinical Research Institute, Seoul National University Hospital,
28 Yongon-dong, Chongno-gu, Seoul 110-744, Korea.
2 Department of Radiology, Asan Medical Center, University of Ulsan College of
Medicine, Seoul, Korea.
3 Department of Pathology, Seoul National University College of Medicine, Seoul
National University Hospital, Seoul, Korea.
Received November 27, 2003;
accepted after revision January 21, 2004.
Supported in part by the 2003 BK21 Project for Medicine, Dentistry, and
Pharmacy.
Address correspondence to J. M. Lee
(leejm{at}radcom.snu.ac.kr).
Abstract
OBJECTIVE. The purpose of this study was to describe the CT and
radiographic features of gastrointestinal stromal tumors of the duodenum.
CONCLUSION. Gastrointestinal stromal tumors of the duodenum appear
on barium studies as extrinsically compressing or submucosal masses with or
without ulceration. These tumors usually appear on contrast-enhanced CT as
well-defined masses with an exoenteric growth pattern and relatively good
heterogeneous enhancement.
Introduction
Gastrointestinal stromal tumors, formerly classified as leiomyomas or
leiomyosarcomas, are mesenchymal tumors of the gastrointestinal tract that
differ from true leiomyomas and leiomyosarcomas
[1]. Moreover, the
nomenclature, cell of origin, and pathologic subclassification of this tumor
have been debated. The c-kit protooncogene protein product CD117 was
found immunohistochemically in gastrointestinal stromal tumors
[2]. The recent availability of
the tyrosine kinase inhibitor specific for KIT, STI-571 (Gleevec
[imatinib mesylate], Novartis) for successful treatment of malignant
gastrointestinal stromal tumors mandates a high level of awareness of
gastrointestinal stromal tumors
[3].
Gastrointestinal stromal tumors most frequently occur in the stomach
(60–70%) followed by the small intestine (20–30%), colorectum
(10%), and esophagus (< 5%)
[1]. Although the radiologic
findings of gastrointestinal stromal tumors have been described recently in
the radiology literature [1,
4–6],
the radiologic features of gastrointestinal stromal tumors resemble those of
leiomyomas or leiomyosarcomas, as has also been previously described
[7,
8]. However, to our knowledge,
the radiology literature is limited regarding the imaging appearance of
gastrointestinal stromal tumors of the duodenum, and no large series focusing
on gastrointestinal stromal tumors of the duodenum has been reported. The
purpose of our study was to describe the CT and radiographic findings of
gastrointestinal stromal tumors of the duodenum.
Materials and Methods
From July 1998 to March 2003, 25 gastrointestinal stromal tumors of the
duodenum were registered at our institution's pathology registry. Five
patients were excluded because a CT scan was not available. Therefore, 20
patients were enrolled in the study. Hard-copy CT scans were available for
nine patients, and CT scan data were available on a PACS (Marotech) for the
other 11 patients. Clinical data were reviewed for patient age and sex and the
presenting symptoms. The institutional review board at our hospital did not
require approval or informed patient consent for the review of medical records
and images.
CT examinations were performed using a Somatom Plus-4 (Siemens Medical
Systems) or a HiSpeed Advantage (GE Healthcare) scanner. Each patient received
120 mL of a nonionic contrast material (Ul-travist 370 [iopromide], Schering)
through an 18-gauge angiographic catheter inserted into a forearm vein. The
contrast material was injected at a rate of 2.5 mL/sec using an automatic
injector. Helical CT was performed in each patient using the following
parameters: a 5- or 7-mm collimation, 1:1 table pitch, and 5- or 7-mm
reconstruction interval. In seven patients, biphasic helical CT scans were
obtained 30 (arterial phase) and 70 (portal venous phase) sec after the
initiation of the contrast material injection. In 13 patients, monophasic
helical CT scans were obtained with a 60- to 70-sec scanning delay (portal
venous phase). An upper gastrointestinal series was performed in 17
patients.
Two radiologists reviewed all the radiologic studies retrospectively, and
final interpretations were reached by consensus. Radiographic findings on
barium studies were reviewed to evaluate tumor location, ulceration, and
morphologic characteristics. We reviewed only the CT scans that had been
obtained during the portal venous phase for the tumor evaluation, whereas we
assessed all the CT scans for the metastasis evaluation. CT scans were
reviewed to determine the size, shape, margin, and pattern and degree of
enhancement of the tumors; the presence of ulceration and calcification within
the lesions; and the pattern of tumor growth (endoluminal, mixed, or
exoenteric). Tumor margins were categorized as well defined (a smooth or
lobular contour without surface projections), irregular (with surface
projections), or clearly invasive (when soft tissue of a similar attenuation
to that of the tumor penetrated an adjacent organ). An endoluminal growth
pattern was defined to be present if the tumor mass attached to the bowel wall
was completely confined to the bowel lumen without bulging into the
extraluminal space. Conversely, an exoenteric growth pattern was defined to be
present if the mass was confined to the extraluminal space without bulging
into the bowel lumen, although extrinsic indentation was observed. A mixed
growth pattern was defined as a typical dumbbell appearance. The degree of
enhancement was judged in comparison with that of muscle and liver: poor
enhancement, identical to or less than that of muscle; moderate enhancement,
more than that of muscle but less than that of liver; and good enhancement,
identical to or more than that of liver. CT findings were also evaluated for
bowel obstruction, bile duct dilatation, abdominal lymphadenopathy, ascites,
and distant metastasis.
The pathology records of all patients were reviewed to establish mitotic
activity and tumor immunoreactivity to CD117. On the basis of previous studies
on gastrointestinal stromal tumors
[9], the criteria of benignity
and malignancy were defined. The histopathologic findings in surgical
specimens were retrospectively reviewed by one gastrointestinal pathologist
with an emphasis on the detection of hemorrhage, necrosis, or cystic
degeneration. A direct comparison between imaging and histopathologic findings
was performed by another pathologist, and two radiologists reviewed the
pathology reports, photographs of gross specimens, and microscopic
examinations.
Results
The study group comprised six men and 14 women who ranged in age from 25 to
75 years (mean, 53 years). Nineteen patients presented with abdominal pain or
discomfort (n = 8), melena (n = 5), symptoms of anemia
caused by occult bleeding (n = 2), vomiting (n = 2),
palpable abdominal mass (n = 1), or jaundice (n = 1). In the
remaining patient, tumors were incidentally detected during a periodic medical
checkup. Seventeen patients underwent surgical removal of the tumor, which
included Whipple operation (n = 3), pylorus-preserving
pancreaticoduodenectomy (n = 6), duodenal resection and anastomosis
(n = 2), and duodenal wedge resection (n = 6). Three
patients underwent only a biopsy for liver metastasis.
On barium studies, eight of the 17 tumors had ulceration. Six tumors,
having ulceration (n = 3) or not (n = 3), appeared to be
smoothly marginated mural-based masses that formed obtuse angles with the
duodenal wall and were compatible with submucosal tumor (Figs.
1A and
1B). Eleven tumors appeared as
an extrinsic compression with (n = 5) (Figs.
2A and
2B) or without (n = 6)
ulceration.
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Fig. 1B. —55-year-old woman with gastrointestinal stromal tumor of
duodenum with low malignant potential. Contrast-enhanced CT scan shows
well-defined mass (arrow) with peripheral high-attenuating rim and
central areas of low attenuation between gallbladder and pancreas.
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Fig. 2A. —45-year-old man with malignant gastrointestinal stromal tumor
of duodenum. Barium study shows extrinsic compression on third portion of
duodenum and focal collection of barium (arrow) in cavity.
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On CT scans, tumors ranged from 2.5 to 13 cm in greatest dimension (mean,
7.2 cm) and 13 tumors (65%) were larger than 5 cm. The 20 gastrointestinal
stromal tumors were located in the first (n = 1), second (n
= 9), third (n = 8), or fourth (n = 2) portion of the
duodenum. Seven tumors (35%) were smooth
(Fig. 3), whereas 13 tumors
(65%) had a lobulated contour (Fig.
4). The tumor margin was well defined in 16 tumors (80%), and two
tumors (10%) had an irregular margin; the remaining two (10%) had invaded
renal vessels (Fig. 4) and the
ascending colon, respectively. Six tumors (30%) had a mixed growth pattern,
and 14 tumors (70%) showed an exoenteric growth pattern. In five of six tumors
showing a mixed growth pattern, the extraluminal portion comprised most of the
tumor volume. Two tumors (10%) showed a homogeneous enhancement pattern
(Fig. 3), but 18 tumors (90%)
showed a heterogeneous pattern. Seven tumors (35%) had good enhancement, 11
(55%) had moderate enhancement, and two (10%) had poor enhancement. On CT,
ulceration was observed in six patients and air–fluid level was observed
in three patients (Fig. 2B).
Calcification was observed in one tumor.
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Fig. 3. —27-year-old woman with malignant gastrointestinal stromal
tumor of duodenum. Contrast-enhanced CT scan shows well-enhancing round
homogeneous mass (arrow) with intact overlying mucosa
(arrowhead).
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Fig. 4. —68-year-old woman with malignant gastrointestinal stromal
tumor of duodenum. Contrast-enhanced CT scan shows lobulated mass lesion
encasing right renal vessels (straight arrow) and inferior vena cava
(curved arrow). Note stomach is dilated as result of duodenal
obstruction.
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No patients had lymphadenopathy or ascites. Duodenal obstruction was
detected in one patient. Liver metastases were present in five patients.
Metastatic lesions in the liver were hypoattenuating during the portal venous
phase in four patients, and metastatic lesions were isoattenuating during the
portal venous phase and hyperattenuating during the arterial phase in the
fifth patient (Figs. 5A,
5B, and
5C). The bile duct was dilated
in four patients, and two patients underwent percutaneous transhepatic biliary
drainage due to hyperbilirubinemia before surgery.
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Fig. 5A. —58-year-old man with gastrointestinal stromal tumor of
duodenum with multiple liver metastases. Contrast-enhanced CT scan shows
well-defined heterogeneous mass lesion (arrow) abutting duodenal
wall.
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Fig. 5B. —58-year-old man with gastrointestinal stromal tumor of
duodenum with multiple liver metastases. Contrast-enhanced CT scan obtained
during arterial phase shows multiple small high-attenuating lesions
(arrows) in liver.
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Fig. 5C. —58-year-old man with gastrointestinal stromal tumor of
duodenum with multiple liver metastases. Contrast-enhanced CT scan obtained
during portal venous phase shows no focal lesion in liver.
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Immunohistochemical studies showed CD117 expression in all patients. Of the
20 gastrointestinal stromal tumors of the duodenum, five were classified as
having low malignant potential and 15 as being malignant. Gross specimens of
14 tumors were available for review. Of the two tumors that showed homogeneous
attenuation on CT, one was a solid tumor without hemorrhage or necrosis at
pathologic examination and the other was a solid tumor containing multiple
punctate hemorrhages. In 12 tumors with heterogeneous attenuation on CT scans,
central areas of low attenuation were found to correspond to necrosis with
hemorrhage (n = 10), the solid tumor itself (n = 1), or
fluid in an ulcer (n = 1).
Discussion
Gastrointestinal stromal tumors of the duodenum account for 10–33% of
all malignant duodenal tumors
[10]. The sex distribution is
approximately equal. Most gastrointestinal stromal tumors of the duodenum are
located in the second or third portion of the duodenum. However, despite their
large size, they rarely cause duodenal obstruction or obstructive jaundice.
The common symptoms of gastrointestinal stromal tumors are hemorrhage, chronic
anemia, palpable mass, weight loss, and abdominal pain
[1]. In our study, these
clinical findings, except equal sex distribution, concur with the literature.
By chance, the five patients whose CT scans were unavailable were men. Thus,
if they had been taken into account, there would have been no sexual
predominance in our sample.
A malignant gastrointestinal stromal tumor appears as a large
well-circumscribed tumor that is usually predominantly extraluminal and has a
heterogeneously enhancing soft-tissue rim surrounding a necrotic center
[1,
4,
5]. Benign gastrointestinal
stromal tumors are often small round or ovoid tumors that are usually
endoluminal and have a homogeneous enhancing pattern
[5,
7,
8]. Generally speaking, the
radiologic features of gastrointestinal stromal tumors of the duodenum seem to
be similar to those that occur in the remainder of the gastrointestinal tract.
In our series, most gastrointestinal stromal tumors of the duodenum—even
small ones—grew in an extraluminal direction and showed heteroge neous
attenuation on CT, whereas other small gastric gastrointestinal stromal tumors
have often shown an endoluminal growth pattern and homogeneous attenuation
[8].
The liver is the most common metastatic site at both presentation and
disease relapse [4]. On CT
scans obtained during the portal venous phase, metastasis in the liver was
usually hypoattenuated compared with the normal surrounding liver
[4,
11]. In our series, one
patient had multiple small liver metastases that were isoattenuating on CT
during the portal venous phase and hyperattenuating during the arterial phase.
We may have missed some hypervascular liver metastases, because biphasic CT
was undertaken in only seven of the 20 patients. The availability of the
tyrosine kinase inhibitor has markedly altered the clinical approach to
gastrointestinal stromal tumor, and this inhibitor has been proven effective
in the management of metastatic gastrointestinal stromal tumor
[3]. Therefore, the detection
of liver metastasis has become more important than ever. Additional studies
may be needed to determine whether biphasic helical CT can detect more liver
metastases than monophasic helical CT in patients with gastrointestinal
stromal tumors.
It may be difficult to determine the organ of origin of a significant
exoenteric tumor from the duodenum using cross-sectional imaging alone. For
example, the differentiation of a tumor located between the duodenum and the
pancreas may be difficult. A gastrointestinal stromal tumor of the duodenum
appears as a well-defined mass with heterogeneous attenuation, whereas a
pancreatic tumor commonly appears as an ill-defined mass with poor
enhancement. However, a solid pseudopapillary tumor of the pancreas may have
features resembling those of a gastrointestinal stromal tumor of the duodenum,
such as a well-encapsulated mass with hemorrhage
[12]. An intact displaced
pancreas head can be observed in patients with a gastrointestinal stromal
tumor of the duodenum, whereas the appearance of a pancreas with a
"beak" suggests a pancreatic origin in patients with a solid
pseudopapillary tumor of the pancreas. We also believe that central gas and a
cavitary mass militate against the diagnosis of a pancreatic tumor.
The differential diagnosis for gastrointestinal stromal tumors of the
duodenum includes primary and metastatic duodenal neoplasms. Adenocarcinoma is
the most common primary malignancy of the duodenum and typically manifests as
an annular narrowing with abrupt concentric or irregular overhanging edges or
as a polypoid tumor mass. Thus, its appearance usually does not overlap with
that of gastrointestinal stromal tumors
[13]. Lymphomas may produce
large ulcerative or cavitary masses that may be indistinguishable from
gastrointestinal stromal tumors on radiologic images. However, the presence of
associated lymphadenopathy favors a diagnosis of lymphoma. Carcinoid tumors
may appear as ill-defined, homogeneous masses with displaced bowel loops.
Paragangliomas are soft-tissue-attenuation masses with homogeneous enhancement
and appear as smoothly margined dumbbell-shaped masses
[14] that could be confused
with gastrointestinal stromal tumors of the duodenum.
In conclusion, gastrointestinal stromal tumors of the duodenum appear on
barium studies as extrinsically compressing or submucosal masses with or
without ulceration. The common CT findings of gastrointestinal stromal tumors
of the duodenum are well-defined exoenteric masses that usually consist of an
irregular central area of low attenuation surrounded by variously thickened
soft-tissue-density walls with or without ulceration.
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Abstract
Introduction
