Keywords:
Pancreatic neoplasms - Pancreatic cancer - Pancreatectomy - Pancreas - Agenesis.
Descritores:
Neoplasias pancreáticas - Câncer pancreático - Pancreatectomia - Pâncreas - Agenesia
INTRODUCTION
The association of a solid pseudopapillary tumor (SPT) with agenesis of the dorsal
pancreas (ADP), both considered as rare entities, has been reported only twice in
the literature: in 2001 by Nakamura et al.[1] and in 2005 by Ulusan et al.[2] This article documents another rare case of this association.
The SPT is a rare type of neoplasm that accounts 1%-3% of all exocrine pancreatic
tumors.[3] It was first described by a pathologist named Virginia Frantz, in 1959.[4] Since then, it has been given several different names, including “Frantz tumor,”
“solid and cystic tumor,” “solid and papillary epithelial neoplasm,” and “papillary-cystic
tumor.” In 1996, the World Health Organization established a new exocrine pancreatic
tumor classification by histological type and defined this pathology as a solid pseudopapillary
tumor.[5]
The SPT most commonly occurs in women, especially in the second and third decades
of life.[6] It is considered a low-grade disease, with good prognosis in most patients. However,
it can also develop into a malignant disease in a minority, with distant and lymph
node metastases, vascular involvement, or recurrence. The most common symptom is abdominal
pain, followed by total absence of symptoms and a noticeable abdominal mass.[7]
ADP is an extremely rare type of condition, and its prevalence remains unknown.[8] Pancreas development is a complex process and involves the fusion of two buds that
grow from the foregut. The ventral bud gives rise to the most part of the head and
uncinate process of the pancreas, while the dorsal bud gives rise to the cranial part
of the head, body, and tail. ADP is caused by lack of regression of the dorsal bud
during embryonic development and can be complete or incomplete.[8]
[9] In the complete form, the accessory papilla, duct of Santorini, the body, and tail
are missing. In the incomplete form, only the tail of the pancreas is absent.[8] Some patients will be accompanied by other diseases, such as pancreatic tumors or
pancreatitis.
CASE REPORT
The present paper reports a case of a 36-year-old woman who sought medical assistance
due to a palpable mass in the epigastrium, which she noticed six months ago. The patient
did not experience abdominal pain, weight loss, and jaundice, and had no history of
pancreatitis. She had insulin-dependent diabetes mellitus for 10 years as the only
comorbidity.
Imaging examinations were performed and tumor markers were measured. Abdominal computed
tomography (CT) ([Figure 1], [2]) showed a large and complex mass with heterogeneous enhancement by intravenous contrast
on pancreatic head topography, measuring 7.8×5.5cm, associated with complete agenesis
of the body and tail of the pancreas. The mass tended to compress the duodenum, portal
vein, and superior mesenteric vein, without signs of invasion. Abdominal magnetic
resonance ([Figure 3], [4]) imaging showed similar characteristics. The radiologists suggested a Frantz tumor
or neuroendocrine tumor as a possible diagnosis. The tumor markers measured were carcinoembryonic
antigen, carbohydrate antigen 19-9, cancer antigen 125, chromogranin A, and 5-hydroxyindoleacetic
acid, which showed normal values.
Figure 1 Abdominal CT showed a large and complex mass with heterogeneous enhancement by intravenous
contrast on pancreatic head topography, measuring 7.8 × 5.5 cm, associated with complete
agenesis of the body and tail of the pancreas.
Figure 2 Abdominal CT showed a large and complex mass with heterogeneous enhancement by intravenous
contrast on pancreatic head topography, measuring 7.8×5.5cm, associated with complete
agenesis of the body and tail of the pancreas.
Figure 3 Abdominal magnetic resonance imaging showed similar characteristics of a large and
complex mass pancreatic head topography.
Figure 4 Abdominal magnetic resonance imaging showed similar characteristics of a large and
complex mass pancreatic head topography.
The patient was referred for surgical treatment. During laparotomy, the body or tail
of the pancreas was missing, and a large mass was noted at the head of the pancreas
with invasion of the second part of the duodenum and adherence to the superior mesenteric
and portal veins. Hence, gastroduodenopancreatectomy with complete resection of the
pancreas was performed ([Figure 5]). The resection was particularly difficult because of the adherence to superior
mesenteric vein. It was necessary minutious dissection, which started with vascular
isolation and preservation. A Rouxen-Y reconstruction was carried out. Latero-lateral
gastrojejunal anastomosis was performed in the alimentary loop, while latero-lateral
hepaticojejunal anastomosis was performed in the biliary loop. The patient was transferred
to the intensive care unit (ICU) immediately after surgery and was eventually moved
to a regular room on postoperative day 2. She showed satisfactory improvements on
the first few days, with good pain control, early ambulation, and good tolerance to
oral feeding. The only complication that the patient developed was a low-output biliary
fistula, which was treated with prophylactic abdominal drainage. The patient was discharged
from the hospital on postoperative day 6 in excellent condition. The patient returned
to the hospital after one week, and the drain was removed; then, she was instructed
to visit the outpatient clinic within a few months for follow-up checkup.
Figure 5 Specimen after resection.
The anatomopathological examination suggested an SPT with 18 lymphatic nodes without
atypical findings. This finding was confirmed by immunohistochemistry, which revealed
diffuse positivity for beta-catenin, cyclin D1, CD-10, and progesterone receptor,
and focal positivity for synaptophysin.
DISCUSSION
SPT is a rare type of exocrine tumor, which typically grows slower and is associated
with fewer or any symptoms. It is usually detected when it has grown into a large
tumor. The rate of diagnosis has been increasing in the last 20 years, probably due
to better accessibility to imaging examinations.[6] Among 2,744 patients with SPT who were identified by Law et al. (2014)[6] in a systematic review, 2,410 of them have been reported between 2000 and 2012,
and only 334 were reported between 1959 and 1999.[7]
The typical clinical picture is a young woman complaining of abdominal pain, which
occurs in 63.6% of the cases. According to Law et al. (2014),[7] 38.1% of the patients with SPT are asymptomatic, 32.5% develop an abdominal mass,
and 19.7% experience nausea and vomiting. Less frequent symptoms include weight loss,
jaundice, and pancreatitis. Women account for 87% of the total patients with SPT,
and the average age was 28.5 years. The average tumor size was 8.6cm; in 59% of the
cases, tumors commonly developed in the body and tail of the pancreas. However, tumor
localization is not very useful for identifying SPT, as the tumor can occur throughout
the pancreas.[7]
Given the excellent prognosis of SPT, establishing the correct preoperative diagnosis
is essential for proper therapeutic planning. Abdominal CT findings usually show a
hypodense retroperitoneal mass that is well defined, encapsulated, and mostly composed
of solid and liquid components, with peripheral calcifications and central areas of
hemorrhagic degeneration that undergo heterogeneous enhancement after administration
of venous contrast, better identified in the arterial phase. The composition could
also be solid or all cystic in a minority of cases. Magnetic resonance imaging (MRI)
can be considered better than CT in some aspects, such as identifying areas of cystic
degeneration, hemorrhage, and the tumor capsule.[10]
[11] Despite the availability of these imaging tools, the pre-operative diagnosis is
complicated by the similarities of the findings between the SPT and other malignant
pancreatic cystic neoplasms. Due to the fact that the final diagnosis of SPT is based
on histopathological examination, some authors suggest the performance of endoscopic
ultrasoundguided fine-needle aspiration biopsy.[12] However, this method remains controversial because of the risk of spreading tumor
cells from a possible malignant lesion.
In general, SPT is classified as a neoplasm of epithelial origin, but the findings
so far are unable to determine the specific cell line. The pathophysiology of SPT,
therefore, remains unknown, and among the possible precursor lines identified by immunohistochemistry
are exocrine epithelial cells (acinar and ductal), neuroendocrine cells, and stem
cells.[13]
The SPT has an excellent prognosis, and the standard treatment is surgical resection.
Normally, the absence of invasion to other organs allows resection with tumorfree
margins. Due to the presence of capsule and the low grade of malignancy, conservative
surgery must be performed. If it is located in the body or tail of the pancreas, distal
pancreatectomy may be performed with spleen preservation if there are no signs of
invasion. Enucleation should be considered for small tumors.[6] Approximately 95% of the patients were reported to be disease free after surgical
removal of the tumors. Law et al. (2014)[7] identified only 29 deaths caused by SPT, and the mortality rate was less than 2%.
The recurrence rate was 4.4%, and the incidence of lymph node metastases was 1.6%.
For this reason, large lymphadenectomies are not recommended.[7] The use of chemotherapy and radiotherapy in the treatment of SPT is limited, and
this may be due to the success of the surgical treatment. The small number of studies
regarding this subject makes it difficult to draw any conclusions.[6]
[7]
A systematic review published in 2009 by Schnedl et al.[14] identified 53 cases of ADP published between 1911 and 2008. They found that 53%
of the patients had diabetes and 53% had abdominal pain. Pancreatitis was detected
in 30% of the patients.[14] In another systematic review, Cienfuegos et al. (2016)[9] identified another 53 cases published between 2008 and 2015, with a total of 106
cases. Approximately 43% of the patients had diabetes, 28% had abdominal pain, and
11% had pancreatitis. Other less frequent symptoms were exocrine pancreatic insufficiency,
jaundice, weight loss, and back pain. Similar to SPT, the increase in the rate of
diagnosis since 2008 is attributed to better accessibility to imaging examinations.[9]
Due to the functional reserve of the pancreas, several SPT patients can remain asymptomatic.
The tail of the pancreas contains most of the islets and consequently the β-cells,
which justifies the appearance of diabetes in the ADP. Abdominal pain might be caused
by exocrine pancreatic insufficiency or chronic pancreatitis.[14]
[15] The association between acute pancreatitis and ADP has been reported in several
studies; among the mechanisms that could explain this association are dysfunction
in the Oddi sphincter, pancreatic head compensatory hypertrophy, increased pancreatic
juice secretion, and pancreatic duct hypertension.[15] Another important consideration is the possibility of pseudoagenesis of the dorsal
pancreas, which refers to the fatty replacement of pancreatic tissue, secondary to
inflammation caused by severe or recurrent pancreatitis. This hypothesis should be
excluded in order to accurately diagnose ADP. The patient in this case had no history
of acute or chronic pancreatitis, which suggests a real ADP.
Some authors have suggested the association between ADP and the occurrence of pancreatic
tumors, but this has not been proven yet. The possible mechanisms remain unclear,
and one of the hypotheses is that ADP increases the risk of chronic pancreatitis and
consequently tumor appearance.[14]
[15] Erotokritou et al. (2018)[16] published a review and reported a case that demonstrated the association between
ADP and a neuroendocrine tumor. They found 15 similar cases with different tumors:
8 cases with pancreatic adenocarcinomas, 1 with intraductal papillary mucinous neoplasm,
3 with periampullary adenocarcinoma, 1 with cystic without cellular atypia, and 2
with SPT.[16]
The two cases showing the association between ADP and SPT were already mentioned in
this article. Nakamura et al. (2001)[1] published the first case, but they suggested an incomplete type of ADP since the
Santorini duct was detected on endoscopic retrograde cholangiopancreatography. The
second case was published by Ulusan et al. (2005),[2] and they suggested a complete ADP, which was examined by conducting a CT scan. In
our case, structures from the dorsal pancreas were not seen on abdominal MRI or CT,
which indicate that it was a true ADP case associated with an SPT.
Bibliographical Record
Daniel Paulino Santana, Diogo Viana Abreu, Edmilson Celso Santos, Bruno de Lima Rodrigues,
Anna Carolina D'Ascenção Maia, Marcos Campos Wanderley Reis. Solid pseudopapillary
tumor associated with agenesis of the dorsal pancreas: a case report. Brazilian Journal
of Oncology 2021; 17: e-20210031.
DOI: 10.5935/2526-8732.20210031
