Pancreatoblastoma in an Adult Patient

Sergio Savastano
1
, Emanuele SG d’Amore
2
, Domenico Zuccarotto
3
,
Oscar Banzato
3
, Mario Beghetto
1
, Barbara Famengo
2
Departments of
1
Radiology,
2
Pathology and
3
Surgery, Ospedale San Bortolo. Vicenza, Italy
ABSTRACT
Context Preoperative diagnosis of a pancreatoblastoma in adults is challenging because of its rarity. Furthermore, difficulties
increase since pancreatoblastomas share radiological findings similar to those found in other masses of the pancreas. Case report A
36-year-old woman was studied with ultrasonography and CT for a mass of the pancreatic head causing obstructive jaundice.
Diagnosis of pancreatoblastoma was obtained with histology and immunohistochemistry of the resected specimen. Conclusion We
reviewed the radiological findings of pancreatoblastomas and possible radiological criteria of differentiation from other pancreatic
tumors. A pancreatoblastoma should be considered in the differential diagnosis of a pancreatic mass presenting atypical radiological
features.
INTRODUCTION
The term pancreatoblastoma was introduced in 1977 by
Horie et al. to describe a rare pancreatic tumor,
previously known as infantile carcinoma of the
pancreas, which shows histological features similar to
the pancreatic tissue at approximately the 7th fetal week
[1]. A pancreatoblastoma typically affects children, but
it can occur throughout one’s lifetime; nevertheless, a
pancreatoblastoma is extremely rare in adults and, to
our best of our knowledge, only 16 cases in adult
patients have been reported in the literature [2, 3, 4, 5,
6, 7].
We herein describe an additional case of a
pancreatoblastoma in an adult woman, focusing on
possible criteria for a differential diagnosis compared
with the other more common tumors of the pancreas in
non-pediatric patients.
CASE REPORT
A 36-year-old woman was hospitalized for obstructive
jaundice. Abdominal ultrasonography showed
dilatation of the biliary tree and a mass in the head of
the pancreas (Figure 1) measuring 4.3x4.7 cm in
diameter and exhibiting a solid but inhomogeneous
pattern because of the presence of a hyperechoic
component.
On dynamic computed tomography (CT), the lesion
showed well-defined margins and inhomogeneous
attenuation due to the presence of both cystic and solid
areas, the latter enhancing in the venous phase; dense
calcifications were also evident (Figure 2a). The tumor
encased the common bile duct; the portal vein was
compressed but patent (Figure 2b); there was no
radiological evidence of local infiltration, or nodal or
distant metastases. Serum levels of tumoral markers
(CA 19-9, CA 125, CA 15-3, alpha-fetoprotein and
CEA) were within reference limits. A preoperative
diagnosis of a solid-pseudopapillary neoplasm of the
pancreas was made on the basis of the radiological
findings.
Figure 1. Abdominal ultrasonography reveals a solid mass in the
head of the pancreas, with an eccentric hyperechoic component
consistent with calcification.
Received December 22nd, 2008 - Accepted January 12th, 2009
Key words Tomography, X-Ray Computed; Diagnostic Imaging;
Pancreas; Pancreatic Neoplasms; Ultrasonography
Correspondence Sergio Savastano
Radiology Department, Ospedale San Bortolo, v.le F. Rodolfi 37,
 
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After positioning biliary drainage to treat the jaundice,
the patient underwent a laparotomy for a Whipple
procedure, but, because the tumor had infiltrated the
portal vein, only debulking of the mass was possible.
The postoperative course was uneventful.
Grossly, on the cut sections, the tumor was whitish-
yellowish, firm and well circumscribed but non-
capsulated. At microscopy, the tumor was mainly
composed of nests and sheets of small uniform
primitive cells frequently showing squamoid nests with
central keratinization; occasional ducts were also
detected. Several calcifications, mainly arising on the
squamoid corpuscles, were also seen (Figure 3ab). The
tumor showed vascular and perineural infiltration and
focal infiltration of a peripancreatic lymph node.
Immunohistochemical stains showed positivity for
cytokeratin 5-6, MNF116 and AE1/3 whereas
cytokeratin 7 and 20, usually staining simple and
glandular epithelia, were not expressed. In addition, a
few endocrine cells could be demonstrated with the
neuroendocrine markers synaptophysin and
chromogranin A. CD99 was also expressed; CD10 and
alpha-fetoprotein were negative.
A final diagnosis of pancreatoblastoma was made on
the basis of typical histological and immuno-
histochemical features.
After surgery, the patient was treated with radiation
therapy and adjuvant chemotherapy; the patient is
currently in good condition without radiological
evidence of recurrent tumor or metastases.
DISCUSSION
Pancreatoblastoma accounts for 0.5% of exocrine
tumors of the pancreas and the highest incidence is
found in the first decade of life with a predilection for
males and Asians [8, 9]. In approximately two-thirds of
cases increased alpha-fetoprotein levels are found, as
occur in hepatoblastoma and other blastomal
carcinomas; congenital pancreatoblastomas are as-
sociated with Beckwith-Wiedemann syndrome [2, 10].
Most pancreatoblastomas exhibit typical genetic
alterations similar to those occurring in hepatoblastoma
and acinar cell carcinoma, but different from those
found in ductal adenocarcinomas [2, 9].
Figure 2. a. On dynamic CT scanning (portal phase), the pancreatic
mass is solid, well demarcated and inhomogenously enhanced; dense
calcifications are evident; as a collateral finding the right kidney
presents pyelectasis from pyelo-ureteral junction syndrome. b.
Coronal reformation displays an intratumoral cyst-like area
superiorly; compression on the portal vein and dilatation of the
intrahepatic biliary tree are also visible. Intraoperatively, the tumor
infiltrates the portal vein.
Figure 3. a. Cords of primitive small cells differentiating into
squamoid nests with central keratinization and intermixed with
several calcifications (hematoxylin-eosin, x400). b. Areas with
squamoid differentiation without calcification (hematoxylin-eosin,
x630).

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A pancreatoblastoma is a slow growing tumor, soft and
well circumscribed, usually very large in size at the
time of diagnosis [2, 8, 9]. Approximately one-half of
the tumors are found in the pancreatic head [3, 10].
Macroscopically, most pancreatoblastomas are
encapsulated and exhibit intratumoral hemorrhage and
necrosis; cystic degeneration and calcifications can
also be found [10]. The tumor is histologically
characterized by different types of epithelial neoplastic
cells arranged in lobules separated by gross fibrous
stroma; cellular types reflect pathways of
differentiation of the embryonal pancreas when the
dorsal anlagen and the ventral anlagen fuse [1]. Solid
sheets of neoplastic cells with an acinar and squamous-
like pattern are evident along with nuclei of
keratinization, the so-called “squamoid corpuscles”,
which represent the most typical aspect of
pancreatoblastoma; immunohistochemistry may show
positivity for acinar, ductal and endocrine
differentiation [2]. Tumors with overlapping features
between pancreatoblastoma and neoplasms with mixed
endocrine and solid-pseudopapillary differentiation
have rarely been noted [11].
Incidental detection of an abdominal mass is the most
frequent clinical presentation of pancreatoblastomas;
symptomatic patients usually complain of abdominal
pain, weight loss, diarrhea and vomiting; instead,
jaundice is rare [3, 4].
Pancreatoblastomas share a similar radiological
appearance in both adult and pediatric patients [5].
Most of the tumors are grossly inhomogeneous with all
diagnostic imaging modalities due to coexisting solid
and cystic areas; septations and calcifications can also
be present [3, 6, 8, 12, 13]. In their series of 10 patients,
Montemarano et al. reported six tumors with well
circumscribed margins on CT scans; however, despite
the fact that radiological findings may suggest an
encapsulated tumor, local infiltration cannot be
excluded preoperatively. In pediatric patients, very
large pancreatoblastomas can not be differentiated
radiologically from hepatoblastoma or other infantile
tumors [3].
Solid components and septa are enhanced after the
administration of contrast medium on CT and magnetic
resonance imaging (MRI). Because of its intrinsic
superior capability of tissue characterization, MRI
better delineates intratumoral hemorrhage and necrosis
areas [3, 5, 6, 8, 12, 13, 14]. On the other hand, CT
better demonstrates calcium deposits, which usually
appear as rim calcifications or foci of punctuate
calcifications [3, 10, 12, 13, 14]. However, as reported
in solid-pseudopapillary neoplasms [15], coarse
calcifications can be detected. Hepatic, lymph nodal
and peritoneal metastases are evident in approximately
30% of cases at clinical presentation; pulmonary and
bone metastases have also been reported [2].
Endoscopic ultrasound is useful for the local staging of
pancreatic cancer, and for assessing vascular
involvement. Although, to our best of our knowledge,
there is no report indicating its role in patients with
pancreatoblastoma, endoscopic ultrasound is expected
to be able to depict the lesion clearly and improve local
staging. In addition, endoscopic ultrasound-guided fine
needle aspiration, or when required, endoscopic
ultrasound-guided tru-cut biopsy, may be performed to
clarify the nature of the pancreatic masses [16, 17, 18].
In adults, the radiological differential diagnosis should
include pancreatic pseudocyst, mucinous cystic
neoplasm, microcystic adenoma, ductal adeno-
carcinoma, endocrine neoplasm, acinar cell carcinoma,
and solid-pseudopapillary neoplasm; pancreatic and
peripancreatic pseudolesions, especially autoimmune
pancreatitis and tuberculosis, should also be considered.
A pancreatic pseudocyst can have inhomogeneous
contents and peripheral calcification, but a history of
pancreatitis and the absence of solid areas leads to the
correct diagnosis [3, 19].
Mucinous cystic neoplasms are predominantly cystic;
calcifications and fluid-fluid level from hemorrhage
can exist but the enhancement of the capsule is
typically delayed [19]. Microcystic adenomas, usually
found in older women, are characteristically composed
of multiple tiny cystic spaces separated by thin septa,
eventually calcified and surrounding central stellate
scar [3]. Ductal adenocarcinomas are often small in
size at the time of diagnosis, and very rarely exhibit
necrosis, hemorrhage or calcifications [3]. Acinar cell
carcinomas can be very large, well circumscribed and
necrotic; metastases are often present, but, unlike
pancreatoblastomas, calcifications are not usually
evident [2, 20]. Endocrine neoplasms of the pancreas
can sometimes be cystic and calcified, but, because
they are hypervascularized, they can be diagnosed
radiologically by early enhancement on dynamic
imaging, even when they are non-functioning [21].
Solid-pseudopapillary neoplasms are low-grade
malignancies of the pancreas, usually very large in size,
encapsulated, containing solid and cystic areas, and
sometimes calcifications; they exhibit a heterogeneous
signal on both T1-weighted and T2 weighted MR
imaging, and heterogeneous, progressive centripetal
enhancement on dynamic imaging [19].
Focal autoimmune pancreatitis can simulate a
pancreatic tumor; however, calcifications, vascular
involvement and loculation are rare. When localized in
the pancreatic head, autoimmune pancreatitis can
determine compression and inflammatory changes of
the common bile duct [22, 23].
Because of caseation, pancreatic and peripancreatic
nodal tuberculosis can show a cystic appearance [22,
24]. It is usually found in immunocompromized
patients and in geographic areas of endemic
tuberculosis, but nowadays, with globalization, it can
be found worldwide.
The prognosis of pancreatoblastoma in the adult
population is poor [2]. Surgery remains the treatment
of choice for both the primary tumor and the
metastases [2, 7]. An empirical approach with
chemotherapy can also play a role in the planning of

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treatment whereas radiation therapy is indicated in the
case of incomplete surgical resection [9].
In conclusion, the preoperative diagnosis of a
pancreatoblastoma is very difficult to reach in adults
mainly because of its rarity; nevertheless, it should be
considered in the differential diagnosis of pancreatic
tumors presenting atypical radiological features.
Conflict of interest The authors have no potential
conflicts of interest
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