AJR 2005; 184:S78-S81
© American Roentgen Ray Society
Pancreatoblastoma in an Adult Woman: Sonography, CT, and Dynamic Gadolinium-Enhanced MRI Features
Joshua L. Rosebrook1,
Jonathan N. Glickman2 and
Koenraad J. Mortele1
1 Division of Abdominal Imaging and Intervention, Department of Radiology,
Brigham and Women's Hospital, Harvard Medical School, 75 Francis St., Boston,
MA 02115.
2 Department of Pathology, Brigham and Women's Hospital, Harvard Medical School,
Boston, MA 02115.
Received April 15, 2004;
accepted after revision June 30, 2004.
Address correspondence to J.L. Rosebrook, MD.
Introduction
Pancreatoblastoma is a rare primary pancreatic neoplasm that
predominantly affects young children, with approximately 100 pediatric cases
reported in the medical literature. The tumor also has been reported in 16
adults. In 2000, Montemarano et al.
[1] described the multimodality
imaging features of pancreatoblastoma in a 10-patient series, including one of
the two adult cases from radiology literature. We report the sonographic,
contrast-enhanced CT, and dynamic gadolinium-enhanced MRI correlative findings
of a histologically proven pancreatoblastoma in a 29-year-old woman. To our
knowledge, this is the third adult case presented in the radiology literature
and the first report of dynamic gadolinium-enhanced MRI features.
Case Report
A 29-year-old asymptomatic African American woman was seen after a newly
converted positive purified protein derivative skin test for tuberculosis.
Results from a screening chest X-ray were normal. The patient's medical
history and physical examination were unremarkable. Before standard treatment
with isoniazid was administered, screening tests were performed that showed
slightly elevated liver aminotransferases. Total and direct bilirubin,
complete blood count, blood chemistries, and pancreatic enzymes were normal.
Serum 
-fetoprotein level was not obtained. The patient denied previous
episodes of pancreatitis; however, during the course of the examinations, the
patient developed abdominal pain that kept her awake at night.
A contrast-enhanced abdominal and pelvic CT was performed to evaluate the
findings and symptoms. A well-defined, heterogeneously dense 2.0 x 1.8
cm enhancing mass with solid and cystic components was identified within the
body of the pancreas (Fig. 1A).
No significant surrounding inflammatory stranding or visible connection to the
normal pancreatic duct was found. No evidence of vascular invasion, distant
metastasis, or associated lymphadenopathy was present. Given the imaging
characteristics, age, history, and sex of the patient, a solid pseudopapillary
tumor of the pancreas was the most likely presumptive diagnosis.
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Fig. 1A. —29-year-old woman with pancreatoblastoma. Contrast-enhanced
axial CT image shows a well-defined mass (white arrow) with cystic
and enhancing solid components in the body of the pancreas.
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Subsequent abdominal sonography revealed a similar sized,
well-circumscribed mass in the body of the pancreas with internal echoes and a
hyperechoic rim demonstrating Doppler flow
(Fig. 1B).
MR images showed a well-circumscribed mass within the body of the pancreas
with a 3-mm-thick rim that demonstrated intermediate signal intensity on
T1-weighted images and low signal intensity T2-weighted images (Figs.
1C and
1D). Centrally, the mass showed
low to intermediate signal intensity on T1-weighted sequences and high signal
intensity on T2-weighted images, suggesting a cystic component. After IV
gadolinium contrast was administered, dynamic imaging showed that the rim
displayed rapid arterial phase enhancement and late washout (Figs.
1E,
1F,
1G,
1H). The mass did not enhance
centrally, again suggesting a cystic lesion or a component of necrosis. Mild
increased T2 signal and contrast enhancement of the surrounding pancreatic
parenchyma suggested an element of mild pancreatitis. Again, the MRI
characteristics were thought to be most consistent with a solid
pseudopapillary tumor of the pancreas. A less likely consideration included an
atypical cystic, nonfunctioning pancreatic endocrine tumor.
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Fig. 1C. —29-year-old woman with pancreatoblastoma. T2-weighted image
shows pancreatic mass with a 3-mm-thick low signal rim (black arrow)
and high signal center (white arrow), indicating a cystic
component.
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Fig. 1D. —29-year-old woman with pancreatoblastoma. Unenhanced fat
saturated T1-weighted image shows pancreatic mass with intermediate signal rim
(black arrow) and low to intermediate signal intensity centrally
(white arrow).
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Fig. 1E. —29-year-old woman with pancreatoblastoma. Dynamic
contrast-enhanced fat saturated T1-weighted images in arterial (E),
portal (F), and equilibrium phases (G) show early and persistent
enhancement within rim of pancreatic mass. Central portion of mass does not
enhance.
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Fig. 1F. —29-year-old woman with pancreatoblastoma. Dynamic
contrast-enhanced fat saturated T1-weighted images in arterial (E),
portal (F), and equilibrium phases (G) show early and persistent
enhancement within rim of pancreatic mass. Central portion of mass does not
enhance.
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Fig. 1G. —29-year-old woman with pancreatoblastoma. Dynamic
contrast-enhanced fat saturated T1-weighted images in arterial (E),
portal (F), and equilibrium phases (G) show early and persistent
enhancement within rim of pancreatic mass. Central portion of mass does not
enhance.
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Fig. 1H. —29-year-old woman with pancreatoblastoma. Time-intensity
curves of the enhancement pattern show the rim of the mass and demonstrate
early and persistent enhancement more than normal pancreatic parenchyma, with
little enhancement centrally.
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Surgical resection of the pancreatic mass by distal pancreatectomy revealed
a 2.5-cm well-circumscribed intrapancreatic mass with extensive central tissue
degeneration and necrosis (Fig.
1I). Microscopically, a peripheral rim of residual viable tumor
was composed of sheets, nests, and trabeculae of small epithelioid cells, with
minimal nuclear pleomorphism and a low mitotic rate
(Fig. 1J). Some foci showed
cytomorphologic features of acinar differentiation, with polarization and
granular cytoplasm; rudimentary ductal structures were present in other areas.
Scattered whorled nests of polygonal to spindled cells with abundant
eosinophilic cytoplasm or squamoid corpuscles were also noted.
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Fig. 1J. —29-year-old woman with pancreatoblastoma. Photomicrograph of
viable portion of tumor shows tumor cells arranged in nests and trabeculae
with focal glandular features (arrow). (H and E, x 100)
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Immunohistochemistry showed the tumor cells were positive for cytokeratins
(CAM5.2, CK19, CK7), neuroendocrine markers (NSE, chromogranin, synaptophysin,
and Leu-7), acinar markers (-1-antitrypsin and
-1-anti-chymotrypsin) for CEA and ß-catenin. Tumor cells stained
negative for CK20, p63, 34BE12, and vimentin.
The morphologic and immunophenotypic features, together with evidence of
mixed acinar, ductal, endocrine differentiation, squamoid corpuscles, and
focal aberrant nuclear staining for ß-catenin, supported a diagnosis of
pancreatoblastoma.
Discussion
Pancreatoblastoma is a rare primary tumor of the pancreas most commonly
seen in patients 1 to 8 years of age; however, rare cases have been reported
[1,
2] in neonates and adults.
Although most cases are sporadic, a congenital form is associated with
Beckwith-Wiedemann syndrome [3,
4]. Pancreatoblastoma is
slightly more predominant in men and two-thirds of cases in the medical
literature have occurred in patients of Asian descent
[2].
Pancreatoblastomas have been well described in the surgical pathology
literature. The largest case series was reported by Klimstra et al.
[4], with 14 new and 41
previously reported cases. Pancreatoblastomas are typically composed of a
mixture of primitive acinar, endocrine, islet cell, and ductal elements,
reminiscent of the incompletely differentiated fetal pancreas at 7 weeks'
gestation [1,
4]. There is no apparent
predilection for the pancreatic head, body, or tail. Grossly, tumors are
partially circumscribed with varying consistency, necrosis, and calcification.
Many have grossly cystic components
[3]. Local extension, vascular,
and perineural invasion have been reported
[4]. Tumors most often stain
positively for pancreatic enzymes, endocrine markers, and carcinoembryonic
antigen. The presence of squamoid corpuscles, a loose aggregate of larger
epithelioid cells of uncertain lineage, is a consistent morphologic feature
[4].
Pancreatoblastomas are often slow growing and relatively asymptomatic. At
presentation, the most common complaints are the presence of an abdominal mass
(50%) and abdominal pain (43%)
[2]. Other presenting signs and
symptoms are usually a result of secondary mass effects on adjacent
organs.
Elevated -fetoprotein is the most common abnormal serological
marker, seen in up to one-third of pediatric cases
[2]. Elevated lactate
dehydrogenase, -1 antitrypsin, and CA 19-9 have also been associated
with pancreatoblastoma [2,
4].
Surgical resection is the treatment of choice for localized tumors and
survival in pediatric cases without metastases is excellent; however, 37% of
cases present with metastatic disease, and treatment is supplemented by
chemotherapy and radiation [4].
In one series, the median survival of patients who died of tumor was 17 months
[4]. The liver is the most
common site for metastasis; however, bone, pulmonary, peritoneal, and
mediastinal metastases have also been described. Overall, adults with
pancreatoblastoma have a poorer prognosis than children, with a 3-year
survival in less than 50% of patients
[2]. In cases with metastases,
pediatric tumors appear less aggressive microscopically and respond better to
treatment than pancreatoblastomas in adults.
Imaging features of pancreatoblastoma have been infrequently described,
with 13 cases reported in the radiology literature. The majority of these
describe findings in children, except Montemarano et al.
[1] and Gruppioni et al.
[5]. Montemarano et al.'s
10-patient series included the first adult case, a 20-year-old woman with a
large, well-circumscribed, heterogeneous mass in the head of the pancreas with
pancreatic ductal and intrahepatic biliary dilatation. Gruppioni et al.
[5] report the second adult
case in a 30-year-old man whose CT showed a well-defined, 8-cm mass in the
head of the pancreas that was heterogeneous on sonography and showed local
vascular invasion by conventional angiography.
Montemarano et al.'s series is the largest reported in the radiology
literature and their findings suggest that the majority of pancreatoblastomas
are large, well defined, at least partially circumscribed, and heterogeneous
masses with low to intermediate signal intensity on T1-weighted images and
high signal intensity on T2-weighted images. Enhancement is a common feature
on contrast-enhanced CT and MR images. Lee et al.
[6] review findings in four
pediatric patients and described well or partially defined tumors with low
attenuation multiloculated elements and enhancing septa on CT and mixed
echotexture with sonography. Roebuck et al.
[7] describe similar primary
tumor findings using CT and unenhanced MRI in four children. No studies
suggest significant differences in the imaging findings of adult versus
pediatric patients.
Our case displayed some typical and atypical features of pancreatoblastoma.
Its small size was atypical given that more than 85% of pancreatoblastomas
reported measure 8 cm or more at presentation
[4]. In addition, this tumor
possessed a well-defined rim of soft tissue demonstrating Doppler flow and
contrast enhancement by CT. On dynamic gadolinium-enhanced MRI sequences, the
rim showed rapid arterial phase enhancement with late washout, indicating its
vascular nature. In contrast, the mass contained central areas of high T2
signal that showed no enhancement. These findings correlated well with the
pathology report that described vascular and viable tumor peripherally with
areas of cystic necrosis centrally.
Although this case report primarily documents the imaging findings of a
rare neoplasm, it also expands the pathologic considerations of primary solid
and cystic neoplasms in the adult pancreas. Pancreatoblastoma is at the
forefront of the differential diagnosis for primary pancreatic neoplasms in
the pediatric population because of its relative frequency in this age group.
In adults, however, more common etiologies for a solid and cystic pancreatic
mass include a solid pseudopapillary tumor, microcystic serous adenoma,
mucinous cystic tumor, intraductal papillary mucinous tumor, or a
nonfunctioning islet cell tumor of the pancreas
[8]. Although the relative
prevalence, sex, age distribution, and clinical presentation may provide
additional clues, overlap remains in the spectrum of radiologic findings. It
is clear that, although rare, pancreatoblastoma falls within this spectrum and
its inclusion in the differential diagnosis of solid and cystic pancreatic
neoplasms in an adult should be considered.
References
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- Klimstra DS, Wenig BM, Adair CF, Hefess CS. Pancreatoblastoma: a
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Introduction
Case Report
