AJR 2004; 183:1844-1846
© American Roentgen Ray Society
Mesenteric Gastrointestinal Stromal Tumor in a Patient with Neurofibromatosis
Rakesh Sinha,
Ratan Verma and
Andrew Kong
Leicester Royal Infirmary Leicester LE1 5WW, England
Glenfield Hospital Leicester LE3 9QP, England
Lyell McEwin Health Service Elizabeth Vale 5112, South
Australia
Gastrointestinal stromal tumors (GISTs) are the most common tumors of
mesenchymal origin in the gastrointestinal tract, mesentery, omentum, and
retroperitoneum. Most GISTs arise in the stomach. The most significant risk
factor for development of these tumors is the presence of neurofibromatosis
type 1 (NF1) [1]. Other risk
factors include urticaria pigmentosa and the very rare familial GIST syndrome.
Although the increased incidence of GISTs in patients with neurofibromatosis
is well documented, especially in the pathologic and genetic scientific
literature, this association has rarely been documented in the imaging
literature. To our knowledge, this is the first imaging report of a patient
with neurofibromatosis and a coexistent GIST.
A 57-year-old man presented with symptoms of gradually increasing abdominal
distention and left upper quadrant pain. He had been previously diagnosed with
NF1. Clinical examination revealed a palpable nonpulsatile abdominal mass in
the upper abdomen. Cutaneous stigmata of neurofibromatosis were noted, and
several neurofibromas were present on the patient's back.
CT of the abdomen and pelvis showed a large 13 x 15 cm mass in the
upper abdomen that appeared to arise separately from the stomach and the small
bowel. This mass showed heterogeneous attenuation and irregular peripheral
enhancement (Fig. 7A). Central
areas of hypodensity were present on the enhanced scans, in keeping with
cystic change. The liver, pancreas, spleen, and both kidneys appeared normal
with evidence of ascites.
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Fig. 7A. —57-year-old man who presented with symptoms of gradually
increasing abdominal distention and left upper quadrant pain. CT scan shows
large mesenteric mass lesion with irregular peripheral enhancement and central
cystic areas arising from gastrohepatic ligament.
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CT also showed a dumbbell-shaped isodense mass in the region of the right
S1 neural foramen with distortion and expansion of the exit foramen (Figs.
7B and
7C). On the basis of radiologic
findings, a diagnosis of mesenteric GIST was suggested along with a sacral
neurofibroma. The abdominal tumor was surgically excised. Histologic findings
showed an intermediate-grade GIST in the lesser sac that arose from the
gastrohepatic ligament with positive immunoreactivity to the tyrosine kinase
growth factor receptor (KIT [CD 117]) stain. Histologic diagnosis of the
lesion in the sacral nerve root from a tissue sample obtained at biopsy
confirmed the diagnosis of a neurofibroma.
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Fig. 7B. —57-year-old man who presented with symptoms of gradually
increasing abdominal distention and left upper quadrant pain. CT scan shows
dumbbell-shaped mass with expansion of right S1 neural foramen.
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Fig. 7C. —57-year-old man who presented with symptoms of gradually
increasing abdominal distention and left upper quadrant pain. Sagittal
reformatted CT scan shows mesenteric and sacral masses (arrow).
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GISTs are the most common mesenchymal tumors of the gut. Their defining
characteristic is the expression of KIT (CD 117). GISTs are thought to arise
from the KIT-positive autonomic pacemaker cells in the gut called the
interstitial cells of Cajal. The incidence of GISTs is estimated to be between
10 and 20 cases per million, and they usually occur in patients who are older
than 50 years. GISTs are the most common smooth-muscle tumors arising in the
gastrointestinal tract from the stomach to the anal canal. Other smooth-muscle
tumors such as leiomyomas are very rare in these sites (the esophagus is the
only site in the gastrointestinal tract in which leiomyomas predominate). The
stomach is the most common site for the development of GISTs, which account
for approximately 2–3% of all gastric tumors
[2]. Less than 1% of
gastrointestinal stromal tumors occur in the mesentery, omentum, or
retroperitoneum [3].
GISTs have a known association with NF1. Gastrointestinal involvement in
NF1 occurs in three principal forms: hyperplasia of the submucosal and
myenteric nerve plexuses and mucosal ganglioneuromatosis; GISTs with varying
degrees of neural or smooth-muscle differentiation; and a glandular,
somatostatin-rich carcinoid in the periampullary region of the duodenum that
contains psammoma bodies and may be associated with pheochromocytoma. In a
large series of 156 GISTs, 6.5% of the cases involved coexistent NF1
[4]. Typically patients with
NF1 have multiple small intestinal GISTs
[2]. Patients with NF1 also
have increased incidence of neuromas and schwannomas occurring in the
gastrointestinal tract. Other conditions that predispose patients to an
increased incidence of GISTs are Carney's complex and urticaria pigmentosa.
Carney's complex is a rare condition that comprises an association among
extraadrenal paragangliomas, pulmonary chondromas, and epithelioid
leiomyosarcomas. Families with KIT germ line mutations also have an increased
incidence of GISTs.
Clinical symptoms are related to the size and location of the GISTs. Most
pathologists use a combination of tumor size and mitotic rate to assess the
malignant potential of these tumors. In general, malignant GISTs are larger,
more cellular, and more mitotically active. GISTs that are smaller than 5 cm
with five mitoses per 50 consecutive high-power fields or less are considered
to be benign with a low risk for metastasis. Tumors larger than 10 cm with
more than five mitoses per 50 high-power fields are considered to be
malignant. All tumors falling between these two extremes are considered to be
of uncertain malignant potential with intermediate risk for metastasis. Tumors
with more than 50 mitoses per 50 high-power fields are considered to be highly
malignant with an aggressive clinical behavior. The liver and the peritoneum
are the most common sites of spread in malignant GISTs
[5].
Mesenteric GISTs are rare and may arise as a primary lesion or as a result
of metastatic spread. Usually metastatic mesenteric GISTs are multiple and may
simulate peritoneal carcinomatosis. In the series reported by Miettinen et al.
[6], the average size of
mesenteric GISTs was 16.5 cm. On CT, mesenteric GISTs are usually
well-defined, lobulated masses that predominantly show heterogeneous contrast
enhancement. Central areas of hypodensity commonly are present because of
necrosis or intratumoral hemorrhage. Intratumoral calcification is uncommon.
Usually the appearance is that of a complex, partially cystic mass that is
indistinguishable from other mesenchymal tumors. The usual treatment of such
tumors is surgical excision, although recently treatment targeted toward
inhibiting the mutant KIT gene by tyrosine kinase inhibiting agent (STI-571)
in recurrent cases has also been very successful.
This case illustrates the increased prevalence and association of GISTs in
patients with NF1. The occurrence of an intraabdominal mass with central
liquefaction should point toward the diagnosis of a GIST. Conversely, the
medical history of NF1 in a patient who has an intraabdominal mass with
nonspecific CT features may help in diagnosing a GIST by virtue of the
well-known association of these two entities.
References
- Fletcher CD, Berman JJ, Corless C, et al. Diagnosis of
gastrointestinal stromal tumours: a consensus approach. Hum
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- Levy AD, Remotti HE, Thompson WM, Sobin LH, Miettinen M.
Gastrointestinal stromal tumors: radiologic features with pathologic
correlation. RadioGraphics2003; 23:283
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- Burkill GJC, Badran M, Al-Muderis O, et al. Malignant
gastrointestinal stromal tumor: distribution, imaging features, and pattern of
metastatic spread. Radiology2003; 226:527
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- Miettinen M, Kopczynski J, Makhlouf HR, et al. Gastrointestinal
stromal tumors, intramural leiomyomas, and leiomyosarcomas in the duodenum: a
clinicopathologic, immunohistochemical, and molecular genetic study of 167
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- De Matteo RP, Lewis JJ, Leung D, Mudan SS, Woodruff JM, Brennan MF.
Two hundred gastrointestinal stromal tumours: recurrence patterns and
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- Miettinen M, Monihan JM, Sarlorno-Rikala M, et al. Gastrointestinal
stromal tumors/smooth muscle tumors (GISTs) primary in the omentum and
mesentery: clinicopathologic and immunohistochemical study of 26 cases.
Am J Surg Pathol1999; 23:1109
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