AJR 2001; 176:921-929
© American Roentgen Ray Society
Making Sense of Mucin-Producing Pancreatic Tumors
John R. Grogan1,
Kia Saeian2,
Andrew J. Taylor1,3,
Francisco Quiroz1,
Michael J. Demeure4 and
Richard A. Komorowski5
1
Department of Radiology, Medical College of Wisconsin, 8701 Watertown Plank
Rd., Milwaukee, WI 53226.
2
Department of Medicine, Medical College of Wisconsin, Milwaukee, WI
53226.
3
Present address: Department of Radiology, Box 3252, University of Wisconsin
Medical School, E3/311 Clinical Science Center, 600 Highland Ave., Madison, WI
53792-3252.
4
Department of Surgery, Medical College of Wisconsin, Milwaukee, WI
53226.
5
Department of Pathology, Medical College of Wisconsin, Milwaukee, WI
53226.
Received July 21, 2000;
accepted after revision October 3, 2000.
Presented at the annual meeting of the Radiological Society of North
America, Chicago, November 1999.
Address correspondence to A. J. Taylor.
Introduction
Over the past several years, mucin-producing pancreatic tumors have become
a much more widely recognized entity. With increasing awareness has also come
an evolution of concepts and nomenclatures regarding this set of pancreatic
neoplasms. Understandably, this maturation process has led to confusion over
categorization, management, and prognosis. This article will propose a
unifying view of these mucin-producing tumors and provide imaging examples for
illustrations.
Mucin-producing pancreatic tumors should be considered when cystic lesions
of the pancreas are found. Most pancreatic "cysts" are
nonneoplastic, usually inflammatory pseudocysts. Approximately 5-15% of these
cystic masses will be neoplastic
[1]. Until 1978, the term
"cystadenoma" was used to describe cystic neoplasms of the
pancreas [2,
3]. At that time, the mucinous
tumors were subdivided from the serous cystadenoma. More recently, the
mucinous tumors have been further subclassified into two major groups:
intraductal papillary mucinous neoplasm and mucinous cystic neoplasm.
These two entities share a common array of epithelia that ranges from
adenomatous, to proliferative ductal epithelium, to invasive carcinoma. These
different epithelia may be present within a single tumor or may evolve toward
the more aggressive form, similar to that of colon carcinoma
[4]. Most consider both
mucinous lesions as at least premalignant if not a low-grade malignancy
[5]. In general, both lesions
are associated with a better prognosis than the more common ductal carcinoma.
However, the intraductal papillary mucinous neoplasm and mucinous cystic
neoplasm differ sufficiently in clinical presentation, anatomic location,
radiographic appearance, and patient demographics
(Table 1) to justify their
division.
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TABLE 1 Patient Characteristics Associated with Intraductal Papillary Mucinous
Neoplasm Versus Those Associated with Mucinous Cystic Neoplasm
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Intraductal Papillary Mucinous Neoplasm
This entity has been referred to by numerous names: mucinous ductal
ectasia, ductectatic cystadenoma or cystadenocarcinoma, mucin-hypersecreting
tumor, mucinous villous adenomatosis, intraductal papillary mucinous tumor,
and intraductal papillary neoplasm. In cases of intraductal papillary mucinous
neoplasm, the abnormal mucin-producing cells line the pancreatic duct.
Frequently, these abnormal cells are found in the side branch system, most
commonly in the pancreatic head or uncinate process. This finding is referred
to as a side branch intraductal papillary mucinous neoplasm
(Fig. 1). The mucinous material
usually distends this local duct system to create a multiloculated
"mass." The subjacent pancreatic parenchyma typically atrophies
and becomes the capsule of the mass. The secreted mucous can spill into the
adjacent duct system with widening of the main duct toward the papilla. The
wide-mouthed papilla expanded by the bulging, glistening mucus has a
"fish-eye" appearance that predicts the presence of an intraductal
papillary mucinous neoplasm at endoscopy
(Fig. 2).
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Fig. 1. —Side branch intraductal papillary mucinous neoplasm. Drawing
shows abnormal cells in uncinate side branches that produce large enough
quantity of mucus (yellow) to distend side branch system. Mucus can
spill over to enlarge adjacent main pancreatic duct. Note that papillary
orifice gapes with extruding mucus. Abnormal cells that are not visible may be
hyperplastic lining (blue). Subtle elevated area or polypoid
projection (purple) can occasionally be seen separate from mobile
mucus.
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Fig. 2. —34-year-old man with pancreatitis who presented for
endoscopic retrograde cholangiopancreatography (ERCP). Endoscopic image shows
patulous papillary orifice (arrow) with mucus bulging into lumen.
Note ERCP cannula (asterisk).
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The mucin-producing cells may also be found in the main pancreatic duct,
labeled as a main duct intraductal papillary mucinous neoplasm
(Fig. 3). The mucin may expand
only a local section of the main pancreatic duct, resulting in a focal
unilocular mass, or the duct distention may be more diffuse with global
parenchymal atrophy.
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Fig. 3. —Main duct intraductal papillary mucinous neoplasm. This
schematic illustrates marked main pancreatic duct distention from mucus
(yellow). Pancreatic parenchyma atrophies. As in side branch
intraductal papillary mucinous neoplasm, abnormal mucus-producing cells are
usually subtle in appearance if seen at all. Blue = hyperplastic cells, purple
= intraluminal excrescences.
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The collection of abnormal ductal cells has a variety of macroscopic
appearances that correlate with their appearance during imaging. Typically,
the focus of abnormal epithelia is difficult to visualize on any imaging study
and during gross pathologic examination. There is a tendency for the benign
epithelia to involve a smaller ductal area and to rarely produce any surface
protuberance when compared with the more aggressive histology. Lesions with
severe dysplasia or cancerous cells will encompass a greater length of duct
and have a more prominent intraluminal projection. However, even the malignant
papillary projections range from only 1.0 to 12.0 mm in height
[4]. Although some researchers
report that these abnormal cells are contiguous
[6], it is more likely that
this is a multifocal process
[7,
8], which has obvious
implications regarding surgical management.
Mucinous Cystic Neoplasm
This cystic pancreatic mass has been previously known as a mucinous
macrocystic neoplasm, mucinous cystadenoma or cystadenocarcinoma, macrocystic
adenoma, and mucin-hypersecreting carcinoma. These tumors vary from 2 to more
than 30 cm in diameter, although they are usually 6-10 cm. The mucinous center
is bounded by a thick fibrous capsule (Fig.
4). The peripheral capsular portion consists of true fibrous
tissue. The inner capsule is composed of ovarian stroma, which is a
characteristic histologic feature of a mucinous cystic neoplasm. The tumor's
epithelial lining is composed of a variable population of abnormal cells. Some
authors [9] conjecture that the
varied distribution of the cells may be caused by pressure necrosis from the
encapsulated mucus. It is this absence of a homogeneous lining that makes
obtaining a representative biopsy difficult and therefore unreliable.
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Fig. 4. —Mucinous cystic neoplasm. Schematic shows mass emanating from
pancreas without connection to duct system. Capsule is formed from outer
fibrous sheath (stippled) and inner ovarian stroma (pink).
Lining may be hyperplastic (blue) or develop intraluminal projections
such as polyps (purple) or septa (white). There may be areas
of normal columnar epithelia, which can result in false-negative findings at
biopsy if more aggressive epithelia present are not sampled. Yellow =
mucus.
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Similar to the intraductal papillary mucinous neoplasm, the mucinous cystic
neoplasm cavity is filled with mucinous material. Papillary projections and
septations can invaginate into the mucin. The capsule or septa can develop
calcifications. Unlike the intraductal papillary mucinous neoplasm, there
should be no ductal communication with the cavity. When present, such
communication is probably related to fistula formation.
Imaging
CT
Both intraductal papillary mucinous neoplasm and mucinous cystic neoplasm
are usually first detected on a CT scan as a cystic mass. The cystic mass
associated with side branch intraductal papillary mucinous neoplasm is
typically located in the head or uncinate process of the pancreas. This
tumefaction is usually described as a collection of 1.0- to 2.0-cm cysts.
However, thin sections and increased IV contrast enhancement protocols allow
one to appreciate that the complex cyst is actually composed of tubes and
arcs. The arcs represent a side branch duct wall, whereas the tubes are the
distended ductal lumina cut obliquely (Fig.
5A,5B).
When this pattern is recognized, we believe it better defines the CT hallmarks
of the side branch intraductal papillary mucinous neoplasm. There may be some
component of associated main pancreatic duct dilatation from mucus spilling
over into the adjacent main duct.
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Fig. 5A. —Side branch intraductal papillary mucinous neoplasm in
46-year-old man with abdominal pain and pancreatitis. CT scan obtained through
pancreatic head shows numerous small "cysts"
(arrows).
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Fig. 5B. —Side branch intraductal papillary mucinous neoplasm in
46-year-old man with abdominal pain and pancreatitis. CT scan obtained 10 mm
caudad to A shows cyst is actually composed of dilated main pancreatic
duct (d) and enlarged uncinate side branch (b), which forms curvilinear
tube.
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A main duct intraductal papillary mucinous neoplasm is visualized as a
diffusely and markedly dilated main pancreatic duct with only a thin remnant
of pancreatic parenchyma (Fig.
6). At times this dilatation may be more focal and appear more
cystlike. As with the side branch intraductal papillary mucinous neoplasm, an
intraductal neoplastic component is rarely visualized.
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Fig. 6. —Main duct intraductal papillary mucinous neoplasm in
66-year-old male renal transplant patient with abdominal pain and recent onset
of diabetes. Unenhanced CT scan through pancreatic body shows diffusely
dilated main pancreatic duct (arrows) with severe parenchymal
atrophy.
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A mucinous cystic neoplasm is depicted as a multilocular or unilocular cyst
in the body or tail of the pancreas (Fig.
7). The presence of any septa will be better appreciated with
contrast enhancement. When multiloculated, individual cysts tend to be greater
than 2.0 cm in diameter and fewer than six in number
[10]. The absence of
peripancreatic abnormality and the lack of change over a 1- to 2-month period
provide greater assurance in the diagnosis of a unilocular mucinous cystic
neoplasm when trying to differentiate this entity from the more common
pseudocyst.
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Fig. 7. —Mucinous cystic neoplasm in 63-year-old woman with pancreatic
mass found at workup for vague left upper quadrant fullness. CT scan shows
complex, multilocular mass involves body and tail. At surgery, this mucinous
cystic neoplasm was found to be malignant with metastatic disease to
liver.
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Endoscopic Retrograde Cholangiopancreatography (ERCP)
ERCP provides critical information to clarify nonspecific findings
especially related to the intraductal papillary mucinous neoplasm seen during
axial imaging studies. Visualizing mucin protruding from the papillary orifice
at endoscopy (Fig. 2) followed
by visualization of mobile intraluminal filling defects on injection of
contrast material will strongly suggest the diagnosis of a mucin-secreting
tumor. It may be difficult to adequately opacify the main pancreatic duct or
its side branches because of the mucus. However, use of a retrieval balloon to
remove intraductal mucus or persistent ductal injection with the ERCP cannula
can help define the duct lumen in spite of the intraluminal material (Fig.
8A,8B).
Persistence in attempting to define the luminal territories of the pancreatic
duct will help distinguish an intraductal papillary mucinous neoplasm from a
mucinous cystic neoplasm.
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Fig. 8A. —Endoscopic retrograde pancreatograms show side branch
intraductal papillary mucinous neoplasm in this 38-year-old man presenting
with recurrent bouts of epigastric pain. Early during injection of contrast
material, filling defects are seen in main pancreatic duct (straight
arrows). Dilated uncinate side branch is partially filled with mucus
(curved arrow), making it difficult to see.
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Fig. 8B. —Endoscopic retrograde pancreatograms show side branch
intraductal papillary mucinous neoplasm in this 38-year-old man presenting
with recurrent bouts of epigastric pain. After most of mucus has been removed
using retrieval balloon, abnormal side branch (arrowhead) can be
readily seen.
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The side branch intraductal papillary mucinous neoplasm will show ectasia
of one or a group of side branches, usually located in the head or uncinate
process. Some of these intraductal papillary mucinous neoplasms have a
stenotic opening into the ectatic segment. Similar to ductal manipulation to
dislodge the mucous from the involved ductal orifice, persistence at
manipulation, such as the use of a retrieval balloon to rake over a questioned
ductal segment that was visualized on a prior imaging study, will frequently
allow visualization of the abnormal side branch.
A main duct intraductal papillary mucinous neoplasm usually has diffuse
ductal dilatation (Fig.
9A,9B).
Even if all the mucus is stripped from the duct, the mucin-producing focus is
only rarely visualized. Mucosal abnormalities, even when present, are usually
subtle, typically granular in appearance, or small papillary lesions. The
greater is the papillary projection, the greater is the likelihood of
underlying malignancy [4].
Rarely, a dominant intraductal mass will be present (Fig.
9A,9B).
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Fig. 9A. —Endoscopic retrograde pancreatogram shows main duct
pancreatic intraductal papillary mucinous neoplasm in this 66-year-old renal
transplant patient with abdominal pain and diabetes (same patient as in
Fig. 6). Early during injection
of contrast material, there is massively dilated main pancreatic duct with
diffuse filling defects.
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Fig. 9B. —Endoscopic retrograde pancreatogram shows main duct
pancreatic intraductal papillary mucinous neoplasm in this 66-year-old renal
transplant patient with abdominal pain and diabetes (same patient as in
Fig. 6). With removal of mucus,
large polypoid mass (arrow) is revealed. Brushings were obtained at
this time.
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Endoscopic retrograde pancreatography (ERP) can also be helpful in defining
a mucinous cystic neoplasm. The presence of ductal communication and the lack
of mobile filling defects are features suggestive of a pseudocyst. The main
pancreatic duct is frequently splayed, narrowed, or even obstructed by the
mucinous cystic neoplasm
[11].
At the time of ERP, an attempt at cell retrieval is probably worthwhile.
Sending aspirated mucus for cytology may show abnormal cells suspended in the
mucinous material. Brushing and forceps biopsy samples may occasionally yield
informative material for study
[12,
13].
There are less well-recognized findings as well. Rarely, calcified
concretions are seen, presumably from dystrophic calcification of mucus plugs
(Fig. 10). Occasionally, duct
ectasia will be present without any definable mucus filling defects
(Fig. 11). This may represent
findings early in the course of this neoplastic process.
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Fig. 10. —56-year-old woman with pancreatitis is shown to have
calcification associated with an intraductal papillary mucinous neoplasm.
Endoscopic retrograde pancreatogram shows calcification (arrowhead)
in main pancreatic duct just above sphincteric segment. This large
calcification straddles junction of main duct and uncinate side branch, which
was later filled.
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Fig. 11. —34-year-old woman with recurrent bouts of pancreatitis.
Endoscopic retrograde pancreatogram shows dilated side branch
(arrowhead), but throughout this and subsequent examinations, no
filling defects were discovered. No mucin was returned on balloon sweeps.
However, because of side branch ectasia, diagnosis of intraductal papillary
mucinous neoplasm was made and subsequently proved at surgery.
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MR Imaging
Until recently, MR imaging and MR cholangiopancreatography were relegated
to serving as problem-solving modalities. Some authors now suggest MR imaging
can replace ERCP in the imaging schema
[8,
14]. MR
cholangiopancreatography is less invasive than ERCP, and at times the subtle
mural abnormalities are better displayed against the homogenous
high-signal-intensity intraductal background of MR cholangiopancreatography.
These findings may be difficult to appreciate in the presence of mucus during
ERCP [14,
15]. T2-weighted sequences and
gadolinium-enhanced images frequently provide better display of the complex
cystic mass associated with the side branch intraductal papillary mucinous
neoplasm than CT scans (Fig.
12A,12B).
For the mucinous cystic neoplasm, the greater contrast resolution of
T2-weighted or gadolinium-enhanced MR images may reveal in better detail the
complexity of a cyst cavity composed of septa or nodules that is displayed as
a unilocular cyst on CT scans (Fig.
13A,13B).
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Fig. 12A. —54-year-old man with recurrent pancreatitis who underwent
both CT and MR imaging for what was eventually found at surgery to be side
branch intraductal papillary mucinous neoplasm. CT scan shows complex cystic
mass (arrow) in pancreatic head.
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Fig. 12B. —54-year-old man with recurrent pancreatitis who underwent
both CT and MR imaging for what was eventually found at surgery to be side
branch intraductal papillary mucinous neoplasm. Gadolinium-enhanced MR image
shows better than CT scan individual ectatic side branches
(arrowhead) forming tubes within uncinate process.
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Fig. 13A —Incidental mass found on lumbar spine MR image in this
80-year-old woman with lower back pain. Diagnosis of mucinous cystic neoplasm
was made on basis of imaging characteristics in association with patient's
sex, age, and lack of presenting complaints. Large mass in pancreatic tail can
be seen on CT scan. Contrast material could not be given because of renal
failure. Mass appears to be unilocular. Notice calcification in wall
(arrow).
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Fig. 13B. —Incidental mass found on lumbar spine MR image in this
80-year-old woman with lower back pain. Diagnosis of mucinous cystic neoplasm
was made on basis of imaging characteristics in association with patient's
sex, age, and lack of presenting complaints. T2-weighted MR image better shows
complex septa not seen on CT scan.
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Certain MR cholangiopancreatography characteristics suggest a malignant
intraductal papillary mucinous neoplasm. A definable intraluminal projection
in either a main duct or a side branch intraductal papillary mucinous neoplasm
markedly increases the likelihood of malignancy
[16]. In the main duct tumors,
the widest segment of ductal dilatation usually correlates with the presence
of abnormal cells [8]. Diffuse
main duct dilatation of maximal diameter greater than 15 mm is associated with
malignant epithelium [8]. There
is also some tendency for larger (>3 cm) side branch intraductal papillary
mucinous neoplasms and associated main pancreatic duct dilatation to harbor
more aggressive epithelia [8,
16,
17].
Sonography
An intraductal papillary mucinous neoplasm or mucinous cystic neoplasm may
be found during abdominal sonography as the first imaging study performed for
abdominal pain. Transabdominal or endoscopic sonography may better define the
internal architecture of a cystic pancreatic mass found at CT. Sonography of
the mucinous cystic neoplasm may show an anechoic unilocular cyst with back
wall enhancement. When present, the multilocular nature of the mass or
septations and, possibly, irregular papillary excrescences coursing through
the center will also be displayed. Occasionally, diffuse low-level echoes,
probably from debris or hemorrhage, can be appreciated. Bright foci within the
cyst wall or septations represent calcifications.
Abdominal sonography for the intraductal papillary mucinous neoplasm is
usually not as rewarding. Frequently, a hypoechoic mass in the pancreatic head
or uncinate process is visualized. The border is usually lobulated.
Occasionally, the cystic ectasia of a side branch can be appreciated. A
markedly dilated main pancreatic duct can be seen in the main duct intraductal
papillary mucinous neoplasm. Frequently, there will be a diffuse, low-level
echotexture. If a large mass is present, it can be visualized within the
expanded duct.
Endoscopic sonography will allow greater detail in depiction of these
mucin-producing tumors. A vague, hypoechoic mass visualized transabdominally
can be displayed as a complex cystic structure with any septation or papillary
projection depicted in detail. Endoscopic aspiration or biopsy at the same
time can provide tissue diagnosis (Fig.
14).
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Fig. 14. —71-year-old man who presented for endoscopic sonography after
detection of incidental pancreatic mass found during CT workup (not shown) for
biopsy-proven hepatocellular carcinoma. Endoscopic sonogram shows pancreatic
mass (arrows) to be complex with thick septa and nodules. Biopsy
sample was obtained at this time. Malignant mucinous tumor, intraductal
papillary mucinous neoplasm, was diagnosed at pathologic examination. Asterisk
= needle.
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Nonimaging Workup
Information gained from imaging is usually adequate to identify and
differentiate pancreatic cystic lesions. However, there are cases in which
other tests are necessary for decision making. The need for other tests is
related to cases in which there is one of the following reasons not to proceed
directly to resection: a potentially malignant mucin-producing tumor needs to
be differentiated from a benign serous cystadenoma before observation; this
mucinous subset of pancreatic carcinoma needs to be confirmed in a patient
with apparent metastatic disease; and mucinous cystic neoplasm needs to be
differentiated from a pseudocyst. Serum CA 19-9 can be used as an initial
screen. An elevated value strongly suggests an underlying malignancy such as
pancreatic ductal carcinoma or mucinous cystic neoplasm as the cause for the
cystic pancreatic mass [18].
CA 19-9 levels are above normal in approximately 80% of patients with cystic
mucinous malignancies, whereas in one study seven of eight patients with
mucinous neoplasm had an elevated serum CA 19-9 level
[18].
If the serum CA 19-9 level is not elevated in a patient with a suspicious
lesion, an aspiration or biopsy sample can be obtained. Some authors suggest
that cyst fluid levels of CA 72-4 provide a reasonable tumor marker. If this
marker is greater than 4 U/mL, there is sensitivity of 80% and specificity of
95% for underlying tumor [18].
Opinions differ about the usefulness of cyst fluid analysis for
carcinoembryonic antigen, amylase, mucin, and glycogen
[18,
19].
Cytologic analysis of the cyst fluid is highly specific and the diagnosis
of malignancy can often be made with confidence, but unfortunately it lacks
sensitivity, which is approximately 50%. Cellular material for analysis can be
found either in the cyst wall or suspended in the cystic fluid. As previously
noted, variable epithelia and discontinuity of ductal cells may cause
aspiration or biopsy to yield false-negative findings. Thus, benign cytologic
findings should be interpreted with caution.
Treatment
The potentially malignant character of both intraductal papillary mucinous
neoplasm and mucinous cystic neoplasm makes complete surgical resection the
treatment of choice. For a lesion in the pancreatic head,
pancreaticoduodenectomy is appropriate. For a body or tail tumor, distal
pancreatectomy is required.
However, these two mucin-producing tumors require different surgical
considerations and are associated with a different prognosis. The complete
removal of a mucinous cystic neoplasm consisting of adenomatous or noninvasive
proliferative epithelia is associated with a favorable outcome. The majority
of patients will have one of these two types of epithelia pathologically and,
therefore, have an excellent prognosis. However, the presence of invasive
carcinoma documented at time of surgery correlates with a poor outcome,
paralleling the course of pancreatic ductal carcinoma. This minority subset of
patients with mucinous cystic neoplasm have a 5-year survival rate of less
than 20% [9].
Surgery for treatment of intraductal papillary mucinous neoplasm can have
its own difficulties. The probable multifocal nature of the abnormal epithelia
makes the use of frozen section at the ductal margins during surgery
imperative. In the otherwise healthy patient, further resection—up to a
total pancreatectomy— may be needed. The type of cellular abnormality
found at resection does not correlate directly with the prognosis. Some
patients with invasive cancer will enjoy a long, disease-free course. Other
patients with apparent benign pathology can develop recurrence. The absence of
good correlation with histology and prognosis may relate to inadequate ductal
sampling at the time of surgery or missing the presence of a more aggressive
cell population during histologic examination of the resected specimen
[7]. The survival rate appears
to be greater than 60% in the overall population of patients with intraductal
papillary mucinous neoplasm
[7].
Differential Diagnoses
Although the intraductal papillary mucinous neoplasm and the mucinous
cystic neoplasm should be considered when a pancreatic cyst, complex cystic
mass, or ductectasia is found, other causes are more common.
Both the acute and chronic changes of pancreatitis mimic the appearance of
mucin-producing tumors. Although a pancreatic pseudocyst may mimic the
mucinous cystic neoplasm, an appropriate clinical history, change in cyst
appearance over time, peripancreatic inflammatory changes, and ductal
communication with the cyst suggest an inflammatory cause. Rarely, a chronic
pseudocyst may be present that may even have peripheral calcification. Small
intra-parenchymal pseudocysts can resemble the side branch intraductal
papillary mucinous neoplasm, but these pseudocysts are usually less numerous
and not tubular in shape when compared with the intraductal papillary mucinous
neoplasm. The main pancreatic duct dilatation of chronic pancreatitis should
be differentiated from the main branch intraductal papillary mucinous neoplasm
by intermittent strictures and a lack of change over time, although
occasionally changes in duct dilatation with chronic pancreatitis can occur
and mimic intraductal papillary mucinous neoplasm (Fig.
15A,15B).
Finally, the noncalcified intraductal concretions associated with chronic
pancreatitis may superficially simulate intraductal mucin. However, with
additional contrast medium injection at ERP or with the use of a retrieval
balloon, the more solid nature of these mobile filling defects and the chronic
inflammatory changes of the main duct and side branches can be
appreciated.
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Fig. 15A. —Chronic calcific pancreatitis simulates intraductal papillary
mucinous neoplasm at CT in this 57-year-old man with recurrent bouts of
pancreatitis. Pancreatic CT performed in 1991 (not shown) showed only subtle
main pancreatic duct dilatation. Six years later, CT shows marked change. CT
scan obtained through body and tail of pancreas shows diffuse dilatation of
main pancreatic duct (arrow) with calcifications
(arrowheads).
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Fig. 15B. —Chronic calcific pancreatitis simulates intraductal papillary
mucinous neoplasm at CT in this 57-year-old man with recurrent bouts of
pancreatitis. Pancreatic CT performed in 1991 (not shown) showed only subtle
main pancreatic duct dilatation. Six years later, CT shows marked change. CT
scan obtained just caudad to A shows complex cystic mass related to
uncinate is present (arrow). Patient had only changes of chronic
calcific pancreatitis at surgical resection without abnormal epithelial
cells.
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Pancreatic ductal carcinoma can present with imaging features resembling
facets of an intraductal papillary mucinous neoplasm or mucinous cystic
neoplasm. A peripancreatic fluid collection from ductal disruption or
decompression related to malignant involvement can have an appearance that is
similar to a mucinous cystic neoplasm
(Fig. 16). Occasionally,
pancreatic duct obstruction from this malignancy results in a markedly dilated
main pancreatic duct suggesting a main duct intraductal papillary mucinous
neoplasm (Fig. 17). Rarely, an
intraductal papillary mucinous neoplasm is mimicked by the pre-dominantly
intraductal growth of a pancreatic carcinoma
(Fig. 18).
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Fig. 16. —Pancreatic carcinoma simulates mucinous cystic neoplasm in
63-year-old woman who presented with left upper quadrant pain and no history
of alcohol abuse. Contrast-enhanced CT scan revealed complex mass
(straight arrows) in pancreatic tail. There is extension of this mass
(arrowhead) into spleen, with splenic infarction and thrombosed
splenic vein. Adjacent pancreas (curved arrow) is abnormally low in
attenuation. At surgery, pancreatic ductal carcinoma was found with extensive
local spread and associated pseudocyst.
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Fig. 17. —Pancreatic ductal carcinoma simulates intraductal papillary
mucinous neoplasm in this 57-year-old man with abdominal distention and
jaundice. CT scan reveals marked dilatation of main pancreatic duct
(arrow). This dilatation with parenchymal atrophy could simulate main
duct intraductal papillary mucinous neoplasm. However, there is dilatation of
biliary tree as well. Biopsy of low-attenuation area within uncinate process
(not shown) revealed pancreatic ductal carcinoma.
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Fig. 18. —Intraductal pancreatic ductal adenocarcinoma simulates main
duct intraductal papillary mucinous neoplasm in this 71-year-old man
presenting with steatorrhea. Endoscopic retrograde pancreatogram shows nodular
filling defect on initial injection of contrast material. On subsequent
injection, this filling defect did not move. There is ductal dilatation
upstream. At surgery, this was ductal pancreatic carcinoma with primarily
intraductal growth.
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Rare tumors of the pancreas may simulate a mucus-producing pancreatic
neoplasm, especially the mucinous cystic neoplasm such as the cystic islet
cell tumor (Fig.
19A,19B)
or a pancreatic sarcoma (Fig.
20). The appearance of a solid and pseudopapillary epithelial
neoplasm may be similar to that of a mucinous cystic neoplasm, but the patient
is usually a young woman or adolescent and the associated mass is usually more
complex (Fig. 21).
Approximately 10% of serous cystadenomas are macrocystic and thus appear
similar to the multilocular mucinous cystic neoplasm
(Fig. 22). Pancreatic cysts
associated with diseases such as autosomal dominate polycystic kidney disease
and von Hippel-Lindau disease may cause confusion. Finally, rarer pancreatic
tumors may have a similar appearance: cystic teratoma, enteric cyst of the
pancreas, lymphoepithelial cysts (Fig.
23), and cystic lymphangioma. If the sphincteric segment of the
main pancreatic duct is selectively obstructed by a periampullary tumor, the
subsequent ductal dilatation and parenchymal atrophy may closely resemble the
intraductal papillary mucinous neoplasm (Fig.
24A,24B).
Similarly, sphincter-of-Oddi dysfunction can rarely affect the pancreatic duct
selectively with subsequent ductal dilatation.
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Fig. 19A. —Islet cell tumor simulating mucinous cystic neoplasm.
38-year-old woman with pancreatic mass found during pregnancy. CT scan shows
cystic mass (arrow) in pancreatic head. At surgery, this mass proved
to be cystic islet cell tumor.
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Fig. 19B. —Islet cell tumor simulating mucinous cystic neoplasm.
63-year-old man who presented with diarrhea. CT scan shows complex mass
(arrow) involving tail of pancreas. At surgery, this mass was
necrotic islet cell tumor of pancreas.
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Fig. 20. —Necrotic pancreatic sarcoma mimics mucinous cystic neoplasm
in this 58-year-old man with left upper quadrant pain. CT scan reveals large
complex mass that could be interpreted as mucinous cystic neoplasm, but at
surgery mass was shown to be sarcoma. Note metastasis to liver
(arrows).
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Fig. 21. —16-year-old girl who presented with mid epigastric pain was
found to have solid and pseudopapillary epithelial neoplasm, which could be
confused with mucinous cystic neoplasm. CT scan shows complex mass
(arrow) in pancreatic head. Even though this mass could simulate
mucinous cystic neoplasm, age and sex of this patient would more likely
indicate solid and pseudopapillary epithelial neoplasm, which was removed at
surgery.
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Fig. 23. —45-year-old woman who presented with epigastric pain. On CT
scan, pancreatic head mass appears fairly well circumscribed and of water
attenuation with small nodule in its wall (arrow). This mass proved
to be lymphoepithelial cyst at surgery.
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Fig. 24A. —28-year-old woman with von Recklinghausen's disease who
presented with complaints of abdominal pain related to pancreatitis. CT scan
obtained through pancreatic body and tail reveals moderate dilatation of main
pancreatic duct (arrow).
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Fig. 24B. —28-year-old woman with von Recklinghausen's disease who
presented with complaints of abdominal pain related to pancreatitis. CT scan
obtained slightly caudad to A shows pancreatic duct dilatation coursing
toward papilla (arrowhead). At surgery, periampullary adenoma was
selectively obstructing pancreatic duct at ampulla.
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Conclusion
The intraductal papillary mucinous neoplasm and mucinous cystic neoplasm
should be considered separate entities even though both contain
mucin-producing epithelia and have malignant potential. The framework of each
lesion is different as are the demographics of the population affected by
these tumors. In general, the prognosis for these tumors is much better than
that for ductal adenocarcinoma. Surgical resection is the preferred mode of
treatment. Recent studies have shown that the presence of invasive carcinoma
associated with these lesions portends an outlook similar to that for ductal
carcinoma.
Acknowledgments
We thank Jan Staedler and Carrie Poole for manuscript preparation and
general assistance.
References
-
Wilentz RE, Albores-Saavedra J, Hruban RH. Mucinous cystic
neoplasms of the pancreas. Semin Diagn Pathol
2000;17:31
-42[Medline]
-
Compagno J, Oertel JE. Microcystic adenomas of the pancreas
(glycogen-rich cystadenomas): a clinicopathologic study of 34 cases.
Am J Clin Pathol
1978;6:289
-298
-
Hodgkinson DJ, ReMine WH, Weiland LH. Pancreatic cystadenoma: a
clinicopathologic study of 45 cases. Arch Surg
1978;113:512
-519[Abstract]
-
Fukushima N, Hasebe T, Shimada K, et al. Intraductal papillary
tumors and mucinous cystic tumors of the pancreas: clinicopathologic study of
38 cases. Hum Pathol
1997;28:1010
-1017[Medline]
-
Thompson LDR, Becker RC, Przygodzki RM, Adain CF, Heffess CS.
Mucinous cystic neoplasm (mucinous cystadenocarcinoma of low-grade malignant
potential) of the pancreas. Am J Surg Pathol
1999;23:1
-16[Medline]
-
Madura JA, Wiebke EA, Howard TJ, et al. Mucinhypersecreting
intraductal neoplasms of the pancreas: a precursor to cystic pancreatic
malignancies. Surgery
1997;122:786
-793[Medline]
-
Adsay NV, Longnecker DS, Klimstra DS. Pancreatic tumors with cystic
dilatation of the ducts: intraductal papillary mucinous neoplasms and
intraductal oncocytic papillary neoplasms. Semin Diagn
Pathol 2000;17:16
-30[Medline]
-
Irie H, Honda H, Aibe H, et al. MR cholangiopancreatographic
differentiation of benign and malignant intraductal mucin-producing tumors of
the pancreas. AJR
2000;174:1403
-1408[Abstract/Free Full Text]
-
Sarr MG, Carpenter HA, Prabhakar LP, et al. Clinical and pathology
correlation of 84 mucinous cystic neoplasms of the pancreas. Ann
Surg 2000;231:205
-212[Medline]
-
Johnson CD, Stephens DH, Charboneau JW, et al. Cystic pancreatic
tumors: CT and sonographic assessment. AJR
1988;151:1133
-1138[Abstract/Free Full Text]
-
Gazelle GS, Mueller PR, Raafat N, Halpern EF. Cystic neoplasms of
the pancreas: evaluation with endoscopic retrograde pancreatography.
Radiology
1993;188:633
-636[Abstract/Free Full Text]
-
Tenner S, Carr-Locke DL, Banks PA, et al. Intraductal
mucin-hypersecreting neoplasm "mucinous ductal ectasia":
endoscopic recognition and management. Am J
Gastroenterol 1996;91:2548
-2554[Medline]
-
Procacci C, Graziani R, Bicego E, et al. Intraductal
mucin-producing tumors of the pancreas: imaging findings.
Radiology
1996;198:249
-257[Abstract/Free Full Text]
-
Koito K, Namieno T, Ichimura T, et al. Mucin-producing pancreatic
tumors: comparison of MR cholangiopancreatography with endoscopic retrograde
cholangiopancreatography. Radiology
1998;208:231
-237[Abstract/Free Full Text]
-
Onaya H, Itai Y, Niitsu M, Chiba T, Michishita N, Saida Y.
Ductectatic mucinous cystic neoplasms of the pancreas: evaluation with MR
cholangio-pancreatography. AJR
1998;171:171
-177[Abstract/Free Full Text]
-
Sugiyama M, Atomi Y. Intraductal papillary mucinous tumors of the
pancreas: imaging studies and treatment strategies. Ann
Surg 1998;228:685
-691[Medline]
-
Yanagisawa A, Ohhashi K, Hori M, et al. Ductectatic-type mucinous
cystadenoma and cystadeno-carcinoma of the human pancreas: a novel
clinicopathological entity. Jpn J Cancer Res
1993;84:474
-479[Medline]
-
Sperti C, Pasquali C, Guolo P, Polverosi R, Liessi G, Pedrazzoli S.
Serum tumor markers and cyst fluid analysis are useful for the diagnosis of
pancreatic cystic tumors. Cancer
1996;78:237
-243[Medline]
-
Carlson SK, Johnson CD, Batts KP, Salomao DR. Pancreatic cystic
neoplasms: the role and sensitivity of needle aspiration and biopsy.
Abdom Imaging
1998;23:387
-393[Medline]
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Introduction
Intraductal Papillary Mucinous...
