AJR 2003; 181:981-985
© American Roentgen Ray Society
Imaging Characteristics of Gastric Lipomas in 16 Adult and Pediatric Patients
William M. Thompson1,2,
Amir I. Kende3 and
Angela D. Levy1,4
1 Department of Radiologic Pathology, Armed Forces Institute of Pathology, 6825
16th St. NW, Washington, DC 20306-6000.
2 Present address: Department of Radiology, Duke University Medical Center, Box
3808, Durham, NC 27710.
3 Department of Gastrointestinal Pathology, Armed Forces Institute of Pathology,
Washington, DC 20306-6000.
4 Department of Radiology and Nuclear Medicine, Uniformed Services University of
the Health Sciences, 4301 Jones Bridge Rd., Bethesda, MD 20814.
Received December 23, 2002;
revised April 4, 2003;
The opinions and assertions contained herein are the private views of the
authors and are not to be construed as official or as reflecting the views of
the Department of the Army or Department of Defense.
Presented at the annual meeting of the American Roentgen Ray Society, San
Diego, CA, May 2003.
Address correspondence to W. M. Thompson
(thomp132{at}mc.duke.edu).
Abstract
OBJECTIVE. The purpose of our study was to evaluate the clinical,
pathologic, and imaging characteristics of gastric lipomas in 16 patients and
to compare them with the characteristics of gastric lipomas described in
previous reports in the literature. We believe that our study was the largest
series that has been reported.
CONCLUSION. Of the 13 patients who had upper gastrointestinal
examinations, seven had findings of smooth submucosal masses with ulcerations
or depressions. These findings overlap with those of a gastrointestinal stroma
tumor and lymphoma. CT findings were specific for the diagnosis of lipoma in
eight of nine patients. CT should be used to evaluate large submucosal masses
in the stomach to establish a preoperative diagnosis.
Introduction
Gastric lipoma is a rare lesion, accounting for only 5% of gastrointestinal
tract lipomas and fewer than 1% of all gastric tumors
[1]. Most gastric lipomas are
small asymptomatic lesions that are detected as incidental findings at autopsy
[1,
2]. The tumor is composed of
well-differentiated adipose tissue surrounded by a fibrous capsule. Most
gastric lipomas are found in the submucosa, and most are located in the
pyloric antrum. When the tumors are large (> 3–4 cm), the most common
clinical presentation is upper gastrointestinal hemorrhage, either chronic or
acute, caused by ulceration of the neoplasm
[2–5].
Abdominal pain and obstructive symptoms are also common, especially if there
is endoluminal growth that could cause intussusception
[1–3,
6]. It is not rare for distal
lesions in the prepyloric area to prolapse into the duodenal bulb
[2].
Classically, imaging findings that suggest the diagnosis of a gastric
lipoma are a smooth, sharply marginated, oval or spherical mass that is
compressible during fluoroscopic examination and may exhibit significantly
decreased attenuation on barium studies
[2,
7]. At endoscopy, some of the
lesions are even translucent enough to allow the correct diagnosis. In other
lesions, ulceration produces a bull's eye appearance, making these lesions
indistinguishable from other submucosal tumors. We believe that this ulcerated
appearance has not been emphasized in the radiology literature. Most lipomas
are solitary, but cases of multiple lipomas have been reported
[8]. CT has proven to be of
considerable value in the diagnosis of gastrointestinal lipomas
[9–12].
The lesions appear as well-circumscribed areas of uniform, fatty density with
an attenuation ranging from –70 to –120 H. Thus, a gastric lipoma
can be definitively diagnosed using CT, which obviates endoscopy or even
surgery if the patient is asymptomatic
[11,
12].
To our knowledge, no large series focusing on gastric lipomas has yet been
reported. We sought to review the clinical, pathologic, and imaging
characteristics of 16 gastric lipomas. We paid particular attention to
comparing the imaging characteristics that we observed with those that have
previously been reported and believe that our study represents the largest
group of gastric lipomas reported in the radiology literature.
Materials and Methods
From 1970 to July 2002, the cases of 16 patients with gastric lipomas were
entered into the radiology–pathology archives of the Armed Forces
Institute of Pathology. We reviewed the clinical data for each patient's age,
sex, and presenting signs and symptoms. Gross pathology specimens were
available for review for 10 of the 16 patients, and histopathology slides were
available for 15 of the 16. The pathology records of each patient were
reviewed to establish the size of the tumor and the presence of ulceration or
necrosis in the tumor and to correlate pathologic findings with imaging
findings.
Upper gastrointestinal examinations were available for review for 13
patients, and CT scans were available for review for nine patients. For six
patients, both gastrointestinal examinations and CT scans were available.
Because patients at the Armed Forces Institute of Pathology are referred from
many institutions, the images were obtained using a variety of equipment and
different protocols, so the acquisition techniques were not standardized. In
addition, only a limited number of images from the upper gastrointestinal
examinations were available.
Two radiologists reviewed the upper gastrointestinal examinations to
evaluate the size, margins, and density of each lesion; presence of
transparency; and evidence of ulceration. CT scans were also reviewed to
evaluate tumor margins and to determine whether fatty density, increased
density within the mass, or ulceration were present. For three patients,
specific Hounsfield values of the lesions were available. The specific
location of each lipoma was determined from the upper gastrointestinal
examinations; CT scans; and, when necessary, endoscopic correlations.
Results
Clinical Findings
Our study population was composed of nine males and seven females whose
ages ranged from 14 to 77 years, with a mean age of 55 years. The most common
symptom was abdominal pain (eight patients) or gastrointestinal bleeding (six
patients). One patient had both of these symptoms, and another had both
abdominal pain and vomiting. One patient had nausea and vomiting, and two
patients without abdominal symptoms had lipomas detected incidentally during a
workup for other medical problems. An upper gastrointestinal examination was
performed in one patient with a history of peptic ulcer disease. All patients
had the lipomas surgically excised.
Pathologic Findings
In all 16 patients, gastric lipomas were confirmed histologically, 15 at
the Armed Forces Institute of Pathology and one at an outside hospital. Gross
pathologic specimens were available for only 10 of the 16 patients with proven
lipomas, but a gross pathologic description was available for all 16. Eleven
lesions were located in the antrum, two in the fundus, two in the pylorus, and
one in the body of the stomach. The average size of the lipomas was 6.5 cm
(range, 3.5–9.0 cm) measured at the greatest dimension. All the lesions
had smooth margins, although some had central ulcerations. The tumors in eight
patients were ulcerated at the time of resection, and the tumors in two
patients had areas of depressions that had undergone necrosis but had not yet
developed into ulcers. These depressions were indistinguishable from ulcers
seen on the upper gastrointestinal examinations.
Imaging Findings
All 13 lesions available for review on the upper gastrointestinal
examinations were detected. Upper gastrointestinal examinations were performed
in six of the patients with ulcers and in the two with central depressions.
These examinations revealed five (83%) of the 13 ulcers (Fig.
1A,
1B,
1C) and both of the depressions
(Fig. 2). In one patient, the
ulcer was not detected; two patients who had ulcers did not have upper
gastrointestinal examinations. Thus, the upper gastrointestinal examinations
revealed seven (88%) of the eight ulcers.
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Fig. 1A. —77-year-old woman with unexplained gastrointestinal bleeding.
Radiograph from upper gastrointestinal examination shows 5-cm antral mass
(arrow) with central collection of barium consistent with ulcer.
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Fig. 2. —40-year-old man with abdominal pain. Spot image from upper
gastrointestinal examination shows 6-cm mass in gastric antrum that contains
central collection of barium (solid arrow). Central collection was
found to be depression rather than ulcer. Pylorus is marked by open arrow.
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One 8.5-cm lesion in the fundus of the stomach was hypodense on the upper
gastrointestinal examination, a finding suggestive of a lipoma
(Fig. 3). All the lesions had
smooth margins (Figs. 1A,
1B,
1C,
2,
3,
4A,
4B,
5), but only this lesion
exhibited the significantly decreased density that is consistent with a
fat-containing tumor (Fig. 3).
The other 12 lesions, particularly the eight with either ulceration or central
depressions, mimicked nonfatty submucosal tumors such as a gastrointestinal
stroma tumor or a lymphoma (Figs.
1A,
1B,
1C,
2,
3,
4A). Two patients with
abdominal pain had pyloric lesions that had prolapsed into the duodenal bulb.
Obviously, compressibility of the lesions could not be evaluated.
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Fig. 3. —45-year-old woman with mass in fundus of stomach that was
identified on chest radiograph (not shown). Radiograph of fundus from upper
gastrointestinal examination shows mass with significantly decreased density
and no ulceration, findings suggestive of lipoma.
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All nine CT scans showed a fatty density. The density of the lesions in
three patients in whom density was measured was –70, –100, and
–117 H, respectively (Figs.
1B,
4B,
5, and
6). One lesion had stranded
soft-tissue attenuation coursing through it
(Fig. 6) and a significant
amount of low-density fat; an ulceration was present in the gross pathology
specimen. Thus, CT findings were absolutely diagnostic in eight of nine
patients (Figs. 1A,
1B,
1C and
4A,
4B,
5,
6) and highly suggestive of the
correct diagnosis in the ninth patient (Fig.
7A,
7B). We found it interesting
that CT revealed ulceration in one (17%) of six patients who had an ulcerated
lipoma (Fig. 1C). The
ulceration was also seen on the patient's upper gastrointestinal examination
(Fig. 1A).
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Fig. 6. —22-year-old man with no gastrointestinal symptoms. CT scan
obtained for follow-up of testicular cancer shows large 9-cm mass
(asterisk) in fundus of stomach. Some high-density areas within mass
are visible, but diffuse low density is diagnostic of lipoma.
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Fig. 7A. —78-year-old woman with acute onset of gastrointestinal
bleeding. Upper gastrointestinal examination showed large 8-cm mass in antrum
with central ulceration. CT scan obtained through antrum shows low-density
mass (asterisk) containing some higher density stranding. Ulcer is
not visible. Higher density is probably due to ulceration.
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Fig. 7B. —78-year-old woman with acute onset of gastrointestinal
bleeding. Upper gastrointestinal examination showed large 8-cm mass in antrum
with central ulceration. Photograph of gross pathology specimen shows typical
features of lipoma extending into lumen. Gastric mucosa is being displaced by
lipoma (arrows). Ulcer is not shown.
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We observed considerable overlap in the size of the lipomas with ulceration
and those without ulceration. The average size of the lipomas with ulceration
was 7.6 cm and ranged from 4 to 9 cm; the average size of the lesions without
ulceration was 6.1 cm and ranged from 3.5 to 9 cm.
Discussion
The symptoms produced by gastric lipomas are related to the size of the
lesion. When small (< 2 cm), lipomas are usually asymptomatic and often
discovered incidentally [1,
2]. Gastric lipomas larger than
3 cm are usually symptomatic. The most common findings previously reported in
the literature
[1–7]—obstruction
and gastrointestinal bleeding—were found in our series. In our 16
patients, abdominal pain was the most common symptom (eight patients, 50%),
with gastrointestinal bleeding present in six patients (38%). In two patients
(13%) with no abdominal symptoms, the gastric lipomas were discovered
incidentally on imaging studies performed for reasons other than upper
gastrointestinal symptoms, an occurrence that is not rare in patients with
gastric lipomas.
The central depressions in the lipomas in two patients were the only
unexpected findings noted in the pathology evaluation. The depressions were
thought to be underlying necrosis of the lipomas with no apparent ulcerations.
Ulceration might have eventually occurred if the lesions were not resected.
These lesions were indistinguishable from ulceration on upper gastrointestinal
examinations (Figs. 1A,
1B,
1C and
2).
Despite the relativity large size of the lipomas, only one in the fundus
exhibited significantly decreased attenuation on the upper gastrointestinal
examination that was suggestive of a lipoma
(Fig. 3). All lipomas had a
smooth surface, even the eight with ulcerations and the two with central
depressions. On upper gastrointestinal examination, most of the lesions
displayed characteristics of a nonfatty mural mass, suggesting that the
lipomas arose from the gastric submucosa or muscular layers, which is where
one might expect to find a gastrointestinal stroma tumor, lymphoma, carcinoid,
or metastasis. The upper gastrointestinal examination was highly sensitive
(88%) for the detection of ulcerations and depressions, which are typical
findings for a carcinoid, lymphoma, metastasis, and occasionally
gastrointestinal stroma tumor
[2,
7]. Lipomas should also be
included in this differential diagnosis.
As we discussed earlier, two of our patients had lesions that had prolapsed
into the duodenum [2]. We also
encountered two lesions that were exophytic, one of which was observed on an
upper gastrointestinal examination to be causing significant external
compression, a finding suggestive of a serosal rather than a submucosal
lesion. CT confirmed the diagnosis of a lipoma in both patients.
CT is the imaging examination of choice for obtaining a specific diagnosis
of lipoma. The smallest lesion revealed on CT was 4 cm and had an ulcer that
was visible on both upper gastrointestinal examination and CT (Fig.
1A,
1B,
1C). A homogeneous gastric mass
with a density of between –70 and –120 H has been previously
reported as pathognomonic for the diagnosis of gastric lipoma
[9–12].
On CT, gastric lipomas have also been reported to display linear strands of
soft-tissue attenuation at the base as well as ulceration of the mucosa that
correlated with prominent fibrovascular septa
[2]. This finding is similar to
that seen in our patient in Figure
7A,
7B. Taylor et al.
[2] believed that the presence
of these strands visualized on CT in an otherwise uniform, fatty tumor should
be taken as a sign of benignity and cautioned against mistaking it for a
liposarcoma, which is extremely rare in the alimentary tract. A gastric lipoma
can usually be definitively diagnosed using CT, thereby obviating endoscopy or
surgery in an asymptomatic patient
[2,
11,
12].
If a large (> 2 cm) submucosal mass is detected on an endoscopic or
upper gastrointestinal examination, a CT scan should be obtained because CT
findings can allow one to make a specific diagnosis of lipoma. If CT does show
the characteristic features of a lipoma, a biopsy is not needed
[3,
6,
11,
12]. Biopsy is indicated in
patients with lesions that are not totally fatty; surgery is indicated in
symptomatic patients [1].
Use of MRI has been limited in diagnosing gastric lipomas
[13], but MRI is extremely
sensitive to fat and could be used instead of CT in certain patient
populations, especially in children and perhaps in patients allergic to
iodinated contrast agents.
Our retrospective study has limitations. It covered more than 30 years, and
the cases studied were collected from multiple institutions. We had the basic
clinical data and good copies of the upper gastrointestinal examinations and
CT scans available for review. Microscopic slides for 15 of the 16 patients
were available for review as were gross specimen photographs for 10 of the 16
patients with gastric lipomas. Therefore, we believe that we have good
clinical, radiologic, and pathologic material to document our findings.
In conclusion, our review of data for 16 patients with proven gastric
lipomas revealed two significant findings. First, on upper gastrointestinal
examinations, lipomas have the appearance of any submucosal tumor; they are
indistinguishable from gastrointestinal stroma tumors or lymphoma. Second, CT
findings are specific for the diagnosis of gastric lipoma. CT should be used
to characterize large submucosal masses before endoscopic biopsy is
performed.
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W. M. Thompson
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Abstract
Introduction
