AJR 2000; 174:1639-1641
© American Roentgen Ray Society
Sonography and CT of Pancreatoblastoma in Children
Arun Kumar Gupta1,
D. K. Mitra2,
M. Berry1,
A. K. Dinda3 and
V. Bhatnagar2
1
Department of Radio-Diagnosis, All India Institute of Medical Sciences, Ansari
Nagar, New Delhi-110029, India.
2
Department of Pediatric Surgery, All India Institute of Medical Sciences,
Ansari Nagar, New Delhi-110029, India.
3
Department of Pathology, All India Institute of Medical Sciences, Ansari
Nagar, New Delhi-110029, India.
Received May 11, 1999;
accepted after revision September 29, 1999.
Address correspondence to A. K. Gupta
Abstract
OBJECTIVE. We reveal the sonography and CT findings of three
children with pancreatoblastoma.
CONCLUSION. Pancreatoblastomas are invasive tumors that encase
adjacent vessels and infiltrate surrounding organs. Original and atypical
findings include metastases to the omentum and lymph nodes of the neck and
direct extension of the tumor to the portal vein and its branches.
Introduction
Pancreatic neoplasms rarely occur in children
[1,
2]. We studied three children
with pancreatoblastoma using sonography and CT. To our knowledge, 60 instances
of pancreatoblastoma have been reported
[1]; only four studies report
imaging findings
[2,3,4,5],
and the remaining studies report fine-needle aspiration, biopsy, or pathologic
results discovered during surgery or autopsy. We report the radiologic
findings of pancreatoblastoma, including atypical features reported for the
first time.
Subjects and Methods
We reviewed the sonography and CT findings of three girls (age range, 4-8
years). All patients presented with histories (range, 6 weeks-5 years) of
upper abdominal mass with or without pain (n = 2) or upper abdominal
pain with frequent loose stools (n = 1). During clinical examination,
large tender firm-to-hard abdominal masses were discovered in two patients. In
the third patient, lymph nodes of the neck were enlarged, and fine-needle
aspiration cytology of the lymph node tissue was suggestive of
pancreatoblastoma. Sonography was performed on an ATL-UM9 HDI scanner
(American Technology Laboratories, Bothell, WA), a 128 XP10 scanner (Acuson,
Mountain View, CA), or a Sonoline Versa Pro scanner (Siemens, Tokyo, Japan).
Unenhanced and enhanced abdominal CT were performed on either a Somatom DRH
scanner (Siemens, Erlangen, Germany) or a Siemens Somatom Plus 4 scanner. All
three patients underwent surgical exploration.
Results
On imaging, large (6-10 cm) and predominantly solid tumors involving either
the pancreatic body and tail only (one patient) (Fig.
1A,1B)
or the entire pancreas (two patients) (Figs.
2A and
3A) were noted. On sonography,
the tumors appeared hypoechoic; however, the extent and the anatomic details
of the tumors were well-depicted on CT. The tumors had heterogeneous
enhancement, and foci of calcification were seen in two tumors
(Fig. 1A). In three patients,
the tumor mass had encased the splenic artery, and in two patients, it had
also encased the celiac artery. The splenic vein had thrombosed, resulting in
the formation of retroperitoneal collaterals. In one patient, the tumor
extended into the portal vein and its branches and produced a large
intraluminal filling defect and multiple collaterals (Figs.
3B and
3C).
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Fig. 1B. —5-year-old girl with pancreatoblastoma. Contrast-enhanced abdominal
CT scan shows tumor (T) involving pancreatic body and tail and sparing head.
Note multiple collaterals (arrows) in splenic hilum caused by splenic
vein thrombosis.
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Fig. 2A. —8-year-old girl with pancreatoblastoma. Contrast-enhanced abdominal
CT scan shows extensive pancreatic tumor (T) with encasement of major vessels
(arrows). Splenic vein was thrombosed with retroperitoneal
collaterals.
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Fig. 3A. —4-year-old girl with pancreatoblastoma who initially presented with
enlarged lymph nodes in neck. Arterial phase contrast-enhanced CT scan reveals
encasement of celiac axis (arrows). Superior mesenteric artery was
also encased.
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Fig. 3B. —4-year-old girl with pancreatoblastoma who initially presented with
enlarged lymph nodes in neck. Venous phase CT scan shows large round filling
defect (tumor extension) in enlarged portal vein (pv) with thin rim of
contrast material at periphery (arrows). Note tumor infiltration in
retroperitoneum, confirming aggressive nature of tumor.
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Fig. 3C. —4-year-old girl with pancreatoblastoma who initially presented with
enlarged lymph nodes in neck. Venous phase CT scan (more cranial than
B) shows poor visualization of intrahepatic portal vein branches with
evidence of intrahepatic collaterals (arrows) and sequelae of portal
vein blockage by tumor.
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Tumor invasion in one or more of the surrounding organs (i.e., duodenal
loop, stomach, spleen, and colon) was observed in all patients. In one
patient, besides the primary tumor, another enhancing omental mass (metastatic
deposit) was also present (Fig.
2B). In all patients, we noted a significant caudal extension of
the primary tumor to the left of the spine, extending down to the left iliac
fossa (Fig. 3D).
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Fig. 3D. —4-year-old girl with pancreatoblastoma who initially presented with
enlarged lymph nodes in neck. CT scan at level of bladder (arrow)
shows very low caudal extension of primary tumor (T) on left side.
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In two patients, we measured 
-fetoprotein levels; one patient had an
elevated -fetoprotein level (1213 µg/l). All three patients
underwent surgery, and the diagnosis of pancreatoblastoma was confirmed with
histopathologic results (Fig.
4).
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Fig. 4. —Photomicrograph of 4-year-old girl with pancreatic tumor shows small
cells arranged in chordlike and trabecular pattern with focal areas of cystic
changes, suggestive of pancreatoblastoma. (H and E, x450)
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Discussion
Pancreatic neoplasms can originate from either endocrine or exocrine cell
types and occur rarely in children
[1]. Among adults, the most
common pancreatic malignancy is ductal adenocarcinoma (extremely rare in
children); among children, the most common pancreatic neoplasms are the solid
and papillary epithelial tumor and pancreatoblastoma
[1]. However, infantile
pancreatic tumors, such as pancreatoblastomas, are relatively rare
[6] compared with other
infantile carcinomas, such as nephroblastomas (Wilms' tumor) and
hepatoblastomas. Other childhood pancreatic neoplasms include the islet cell
tumor, hamartoma, lymphoma, haemangioendothelioma, lymphangioma, sarcoma, and
benign lesions such as congenital cysts
[6,
7].
Pancreatoblastoma has a unique microscopic appearance
[8,
9]. Although researchers note a
male preponderance [1], all our
patients were girls. An association between Beckwith-Wiedemann syndrome and
pancreatoblastoma has also been reported
[1,
4]; however, none of our
patients had this syndrome. Pancreatoblastomas are reported to be large, as
were the tumors in our patients. Elevated levels of -fetoprotein have
also been reported [1,
3,
4], but only one of our
patients had an elevated level.
A study by Horie et al. [8]
suggests that pancreatoblastomas are caused by the persistence of fetal anlage
of pancreatic acinar cells during the eighth week of embryologic development.
Although the tumors can originate anywhere in the pancreas, Horie et al.
divided pancreatoblastomas into two categories: those arising from the ventral
anlage (right-sided tumors) and those arising from the dorsal anlage
(left-sided turmors) of the pancreas. Horie et al. and other investigators
have observed that ventral anlage tumors are usually well encapsulated, do not
contain islet cells, do not show calcification, and generally have a good
prognosis; dorsal anlage tumors contain islet cells, lack encapsulation, show
calcification, and generally have a poor prognosis
[1,
4,
8]. All our patients had tumors
that were highly aggressive and encased the celiac axis, splenic artery, and
superior mesenteric artery; thrombosed the splenic vein; and infiltrated
adjacent organs. Two of the tumors had metastasized into the lymph nodes of
the neck and the omentum, and the third tumor showed liver metastases at
follow-up. Two tumors also showed calcification. The highly aggressive
behavior of these neoplasms suggests that they belong to the category of
tumors that originate from the dorsal anlage of the pancreas, according to
Horie et al. This assumption is supported by the observation that all three
tumors were located predominantly to the left of the spine with significant
caudal extension. Probably because the tumor originated in the dorsal anlage,
the predominant bulk of the tumor mass was located on the left side of the
spine; therefore, caudal extension was only observed on the left side.
As previously mentioned, one of our patients had metastases in the lymph
nodes of the neck. The aspiration cytology of this patient's tissue was
suggestive of pancreatoblastoma. To our knowledge, no patient has ever had a
similar clinical presentation. Another patient had omental metastasis with
enhancing characteristics similar to that of the primary tumor. Although an
omental deposit in a solid and papillary neoplasm has been reported
[10], we have not found any
report of pancreatoblastoma with this pattern of metastasis. In one of our
patients, the extension and infiltration of the tumor in the portal vein and
its branches resulted in the marked dilatation of these vessels on color
imaging, with only a peripheral rim of flow visible. Contrast-enhanced CT
revealed numerous collaterals, and to our knowledge, the involvement of the
portal vein by a pancreatoblastoma has not been previously reported. The
direct spread of the pancreatic tumor in the portal vein was probably caused
by the extension of the tumor through the subperitoneal space, which is a
potential continuous space connecting the peritoneum, retroperitoneum, and
abdominal organs [11].
Previous articles report nonspecific MR imaging characteristics for
pancreatoblastoma, including low signal intensity on T1-weighted images and
bright signals on T2-weighted images
[1,
3,
5]. None of our patients
underwent MR imaging.
Pancreatoblastoma, though rare, is the most common pancreatic tumor in
children. The highly aggressive biologic behavior of the tumors in our
patients, with encasement of arteries, thrombosis of the splenic vein, and
extension in the lumen of the portal vein and other organs, support earlier
reports that left-sided tumors are more aggressive than right-sided tumors.
Metastases to distant lymph nodes of the neck and to the omentum can occur.
Knowledge of the biologic behavior of these tumors and awareness of the
imaging findings help in the preoperative diagnosis of pancreatoblastomas.
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Abstract
Introduction
