Intraductal papillary mucinous tumor (IPMT) of the pancreas with
malignant degeneration into adenocarcinoma
SURGICAL AND PATHOLOGIC FINDINGS
In our patient, the hypodense solid mass is typical of duct-cell
adenocarcinoma, while the small adjacent cysts are typical for
branch-duct IPMT. The main pancreatic ductal marked dilatation and
parenchymal atrophy suggest that main-duct IPMT was present as
well. An intraoperative evaluation showed a palpable solid
pancreatic head mass with no other palpable pancreatic
abnormalities. During incision of the pancreatic mass, cloudy
whitish fluid was observed that was thought to be from the
pancreatic duct. Histopathologic evaluation of the surgical wedge
biopsies found mucinous cells arising from the pancreatic duct
epithelium (Figure 2A). The solid pancreatic mass was found to
represent poorly differentiated invasive adenocarcinoma (Figure
Contrast-enhanced computed tomography (CT) performed with 5-mm
thick slices obtained at 5-mm intervals revealed a 3.5-cm solid,
slightly hypodense, pancreatic head mass with obstructive
dilatation of the intrahepatic biliary, common bile, and pancreatic
ducts (Figure 1). The pancreatic duct measured 2.0 cm in diameter.
The pancreatic parenchyma was marked-ly atrophic. Small cysts were
present in the pancreatic head adjacent to the solid mass. No
regional lymphadenopathy or solid hepatic lesions were seen.
Intraductal papillary mucinous tumor, which was first described in
1982, is either a new pancreatic entity or a previously
miscategorized tumor. In 1996, the World Health Organization
separated mucinous ductal ectasia of the pancreas from mucinous
cystadenomas and officially assigned the name intraductal
papillary mucinous tumor of the pancreas.
Approximately 1% of
all pancreatic malignancies and 10% to 13% of pancreatic cysts are
A premalignant or malignant neoplasm of
pancreatic ductal epithelium, IPMT often masquerades as idiopathic
chronic pancreatitis. In contrast to other pancreatic cystic
lesions, IPMTs are intraductal and have a marked mucin
hypersecretion, which results in characteristic imaging and
endoscopic appearances. The diagnosis is made using a combination
of CT, magnetic resonance imaging, endoscopic retrograde
cholangiopancreatography, endoscopic ultrasound, and biopsy.
Although it is well known that IPMTs can be malignant at
presentation or can undergo malignant transformation, to our
knowledge, an imaging diagnosis of coexisting benign-appearing IPMT
and carcinoma has not been reported.
IPMT is characterized by intraductal cuboid or tall columnar
epithelium proliferation and abundant mucin production that causes
ductal dilatation. Cells are arranged in a papillary or cribriform
configuration in ectatic or cystically dilated pancreatic ducts.
The World Health Organization classification divides IPMT
intraductal epithelial dysplasia into adenoma, borderline tumor,
and carcinoma.3 This histologic continuum from
hyperplasia and dysplasia to invasive carcinoma can be found within
a single pancreas representing evolution to malignancy versus
multicentricity of dysplastic epithelium.4 Roughly 30%
to 40% of patients with IPMTs have invasive malignancy at the time
of diagnosis, and the remaining patients have atypia, dysplasia, or
carcinoma in situ, all of which illustrate IPMT's premalignant
Currently, IPMTs are categorized into main-duct (diffuse or
segmental) and branch-duct (microcystic or macrocystic) types.
Main-duct IPMT is usually multifocal and represents a global ductal
epithelial disorder. A macrocystic branch-duct tumor is
characterized by unilocular or multilocular architecture. A
microcystic branch-duct tumor is manifested by multiple thin septa
that separate small cystic spaces.
Diagnosis is not usually made until 5 to 6 years after the onset
of symptoms, which include weight loss, jaundice, anorexia,
steatorrhea, and diabetes mellitus. Invasive malignancy is
diagnosed in 30% to 45% of patients at the initial staging. An
elevated CA19-9 level has been correlated with invasive
disease.6 A recent study found a correlation between the
average size of a soft tissue mass associated with IPMT and
pathology: 2.0 cm for hyperplasia; 3.0 cm for adenoma; and 4.8 cm
for adenocarcinoma.4 Additional studies that evaluated
IPMTs with axial imaging found septations in 49%, filling defects
in 31%, nodular soft tissue regions in 5%, multiplicity of lesions
in 23%, and bulging papilla in 25%.7,8
Total pancreatectomy is the suggested treatment in most cases,
since IPMT is considered to be a premalignant state that involves
the entire pancreatic ductal epithelium. Subtotal pancreatic
resections are performed according to the patient's underlying
morbidity and compliance and for palliative
In many patients (particularly those with the branch-duct type),
the tumor is an incidental finding. Serial evaluation of small
cystic lesions has documented a predilection for the malignant
progression of main-duct lesions and the stability of branch-duct
lesions. Isolated branch tumors that are <2.5 cm and do not have
a solid component can be observed, since these are usually
adenomas.8 For IPMTs that originate in a branch duct,
resection is recommended if the main duct is dilated.
We conclude that when a mass that is consistent with duct-cell
carcinoma is seen adjacent to a cystic mass that is consistent with
IPMT, the diagnosis of adenocarcinoma coexisting with IPMT can be
suggested. This could be the result either of malignant
degeneration of IPMT or a manifestation of de novo malignant
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- Warshaw AL, Compton CC, Lewandrowski K, et al. Cystic tumors of
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