Cystic of the Pablo
Masses
R. Ros,
MD
JenniferE. Hamrick-Turner, Maria V. Chiechi, MD Luis H. Ros, MD Patricia Gallego, MD Sharon S. Burton, MD
Although
the
creas
pseudocyst
found
multiple
is the
at imaging
disease
article mass,
MD2
processes
reviews including
although
makes it generally ing the findings ferential
can
manifest
and
magnetic
the
considerable
impossible from these
diagnosis.
cystic
a cystic
in a similar
This
studies
of imaging
diagnosis, in formulating
of the
pancreas
combina dif-
is not
be followed of the cystic
are
features
always
by cytologic mass may also
necessary. INTRODUCTION
U
Cystic
lesions
in routine cysts tic
of the clinical
arising
an ample
Index 77.32
of the
findings
terms: Pancreas,
I From
the
Institute
goza, Zaragoza, RSNA scientific March Current
e RSNA,
27. Address address:
entities
frequently lesions
the
can
with
of the
radiologist
produce
the
imaging
pancreas should
imaging
are be
aware
appearance
studies pseudothat
of a cys-
a classification
of cystic
masses
in the
pancreas
(Table)
and
a
77. 1 2 1 1
Pancreas,
cysts,
#{149}
77.3
12
Pancreas,
MR.
#{149}
77. 1 2 14
Pancreas,
#{149}
neoplasms,
77.31,
12:673-686
Department
of Radiology,
FL 32610-0374
of Pathology,
cystic
at imaging.
Pancreas, CT, US, 77.1298 1992;
Gainesville,
relatively
most
pancreas. presents
#{149}
detected
of pancreatitis,
of pathologic
article
RadioGraphics
cAne,
are Although
as a consequence
in the
review
pancreas practice.
gamut
mass This
2
manner.
imaging
a specific is helpful
mass
pan-
of the
of the origin of the neoplastic. Computed
overlap
a pseudocyst, percutaneous drainage should analysis of the aspirate. A biopsy of the wall be
of the
be aware
resonance
to render modalities
Because
mass
should
entities by category inflammatory, and
ultrasound, and,
common
radiologists
that
these other congenital,
tomography, presented,
most
studies,
Box
100374,
(P.R.R.,J.E.H.T.,
Washington,
DC (P.R.R.);
Spain (L.H.R.); and Department assembly. Receivedjanuary 30, reprint Department
requests
J. Hulls M.V.C.,
Miller S.S.B.);
Department
Health
of Radiology,
of Radiology, 1992; revision
Center,
Department
Hospital requested
University
of Florida
ofRadiologic Hospital
Pathology,
Miguel
Servet,
Militar, March
Bogota, 5 and
Colombia received
Medical
Center,
Jackson.
College Armed Universidad
of Mcdi. Forces de Zara.
(PG.). From the March 22; accepted
1991
to P.R.R. of Radiology,
University
of Mississippi
1992
673
a.
b.
Figure 1 . Single true cyst of the pancreas in a 56-year-old woman. (a) uation equal to that of water. The mass does not appear enhanced with (arrows). (b) Photograph shows resected tail of the pancreas containing
of the wall demonstrated
U
CONGENITAL
.
Single
A true
the presence
CYSTIC
True
ing
its inner
is derived
from
pancreatic
multilocular
a few
cysts
and
congenital most
have
are
been
seen
in
reported
may be unilocular
usually
microscopic
to 5 cm
computed anechoic,
tomography
range
in size
or
from
uation
Ultrasound (US) and demonstrate an low-attenuating mass with an attencoefficient of 0-20 HU, which is typical
of any
simple
after
RadioGraphics
cyst.
intravenous
material
U
Isolated rare;
an
ducts lin-
(1-3).
True
674
(1).
extremely
although
in adults
(Fig
No
(1).
(CT)
enhancement
administration 1).
U
helped
confirm
the diagnosis
of Cystic
Masses
of a true
cyst.
of the
Cyst
surface are
and
Classification Pancreas
abnormal segmentation of the primitive of the pancreas and has a true epithelium true cysts newborns,
lining
MASSES
of the pancreas
cyst
of epithelial
CT scan shows a cystic mass of attenadministration of contrast material a true cyst. Histologic examination
is seen
of contrast
Congenital cystic masses Single true cyst Multiple true cysts In adult polycystic kidney disease In von Hippel-Lindau disease In cystic fibrosis Inflammatory cystic masses Pseudocyst Abscess Echinococcus cyst Neoplastic cystic masses Benign neoplasms Microcystic adenoma Cystic teratoma Malignant or potentially malignant Islet cell carcinoma Mucinous cystic neoplasms Solid and Lymphoma Anapiastic
Ros et a!
papillary
epithelial
neoplasms
neoplasms
carcinoma
Volume
12
Number
4
Figures
2, 3.
polycystic massive
kidney involvement
(2) Typical
presentation
of adult
disease. CT scan demonstrates of the kidneys and mild involvement of the liver. In the pancreas, only a very small cyst (arrows) is identified. (3) Atypical presentation of adult polycystic kidney disease. (a) US im-
age demonstrates multiple large cysts in the pancreas in a 2-month-old male infant. (b) CT scan also shows with
predominant only
involvement
a few
cysts
in the
of the
kidneys
pancreas,
liver.
and
2.
.
Multiple
True
CT and
Cysts
Most congenital cysts of the pancreas are multiple and are associated with genetic disorders that involve cystic disease in other organs, including adult polycystic kidney disease, von Hippel-Lindau disease, and cystic fibrosis; these cysts may also occur as solitary lesions. Multiple true cysts of the pancreas are seen in approximately polycystic
10% kidney
ofpatients
disease
(4).
with These
usually small and may either diffusely the pancreas or localize to one region. number of cysts varies, but, typically, atic
involvement
is less
seen in the kidneys and pancreatic involvement (Fig 3).
July
1992
than
liver may
the
cystic
adult cysts
are
involve The pancre-
lesions
US findings
are
cysts.
similar
of the individual
to those
Concomitant
hepatic
ment facilitates diagnosis seen in the pancreas. In von Hippel-Lindau in the
kidneys,
spleen, nal cell
for
adrenal
in addition carcinoma
single
and
when disease, glands,
cystic true
renal
involve-
cysts
also
cysts liver,
to the pancreas and microcystic
are
pancreatic
proximately
cysts 30%
(5,6). Readenoma
are demonstrated
of patients
who
seen
and
of the pancreas are also associated with disease (6). In this autosomal dominant der,
are
this disor-
in apundergo
change
(Fig 2). Rarely, predominate
Ros et a!
U
RadioGraphics
U
675
Figures 4, 5. (4) von the tail of the pancreas.
Hippel.Lindau
Note
disease
the surgical
in a 66-year-old
clips
from
woman.
a previous
(a)
CT scan
left adrenalectomy
shows
a cyst
(arrows)
in
for pheochromocytoma
(arrowhead). (b) Ti-weighted MR image (repetition time, 300 msec; echo time, 20 msec [300/20J) shows the cyst as a focal area of low signal intensity (arrows) . (c) Photograph of a cut section of the cyst attached to the tail of the pancreas demonstrates thin walls and several loculi. (5) CT scan demonstrates extensive involvement of the pancreas by multiple cysts in von Hippel-Lindau disease (long solid arrows), which led to diabetes. There is also a renal right kidney (open arrows).
imaging
studies,
indicate
that
but true
data
cysts
cell
obtained are
creas in a greater proportion Imaging studies demonstrate pancreas and other abdominal 5).
Not
infrequently,
calcification which images
these
in the
are
seen
carcinoma
periphery
as acoustic
at autopsy
found
in the
of cases cysts organs cysts
in the
show
(5). in the (Figs
on
U
RadioGraphics
4,
seen,
usually
CT scans HU)
there
findings
replaced echogenic
cysts,
of the in chronic
show
cysts
lesions
parenchyma fat
and
multiple
which
pancreatic
for
di-
ducts,
are
(7).
disease
as low-attenuation
surrounded
surrounding (8).
Rarely,
represent
by pancreatic
-
typical
in the
replacement
(7,8).
in a range relative to 120 HU) (Fig
(-90
cysts
is fatty
parenchyma true
remnants
cal
Ros et a!
Eventually,
(0-25 US
arrows)
pancreatic
lated of
(6).
U
solid
macroscopic
Progressive dilatation of the acini and pancreatic ducts with secondary fibrosis and i-csultant pancreatic atrophy is seen in cystic
676
(short
fibrosis.
on CT scans, shadowing
kidney
of the
pan-
foci
left
a simple
to that of typi6). US shows
cyst.
The
parenchyma
Volume
fatty-
appears
12
Number
4
a.
b.
Figure
6.
Cystic
creas (solid tion (open
fibrosis
arrows). arrows).
in an 1 1-year-old
girl.
(a) CT scan
demonstrates
Note fatty replacement of the pancreatic parenchyma, (b) US image helps confirm the cystic nature of the
a.
a cystic shown mass seen
mass
in the
as an area with CT.
tail of the of low
pan-
attenua-
b.
Figure
Pancreatic pseudocyst. (a) CT scan demonstrates a pseudocyst anterior to the tail of the pancreas. the enhancement of the fibrous wall (arrowheads) of the pseudocyst. (b) Low-power photomicrograph (original magnification, x 40; hematoxylin-eosin stain) shows the fibrous wall of a pseudocyst (anrows) anterior to the tail of the pancreas (T). Note the presence of debris (D ) in the lumen of the pseudocyst, indicating a previous hemorrhage. A vessel (arrowhead) is noted in the fibrous wall.
U
7. Note
INFLAMMATORY
CYSTIC
. Pseudocyst The most common is a pseudocyst, tion 2%-3%
of acute
cystic which
pancreatitis
of all cases
mass
is seen
MASSES
of the pancreas as a complica-
in approximately (9).
These
cystic
structures
are characterized microscopically by a fibrous wall, which develops over a period of approximately 6 weeks (Fig 7) (10). These cystic structures do not have an epithelial lining and are thus pseudocysts (1). The fibrous wall surrounds a collection of pancreatic fluids, cellular debris, and blood (1 1).
July
1992
On US images, pseudocysts are usually welldefined, smooth-walled, anechoic masses, although they may occasionally be multilocular with internal septations. Internal echoes or a fluid-fluid
level
may
be
seen
with
hemor-
rhage or infection. On CT scans, an uncomplicated pseudocyst should appear as a well-dcfined wall or capsule, with a central area of low attenuation and an attenuation coefficient
within
a range
relative
to that
Ros et a!
of water
U
RadioGraphics
U
677
Figure 8. Pancreatic abscess. (a) CT scan demonstrates a low-attenuation pancreas, which contains multiple gas bubbles. The presence ofgas bubbles characteristic of pancreatic abscess. (b) Photograph of a surgical specimen replacing pancreatic parenchyma.
a. Figure
to the tail of the
is the most helpful imaging shows greenish purulent fluid
b. 9.
Hydatid
disease of the liver and pancreas. (a) CT scan shows ofthe liver (large arrows) and a second, smaller multilocular cyst in the (b) Photograph of a specimen from a liver echinococcus cyst demonstrates
the cyst, with
daughter
(Fig
7). Magnetic
may
be
ciated
helpful
cysts
resonance to detect
splenic
and
vein
hydatid
(MR) hemorrhage
studies
cite
percentages
of
1%-21%
imaging or
asso-
Radiologically, in contrast to a pseudocyst, which usually has a distinct wall or capsule, pancreatic abscess generally has indistinct margins (Fig 8) (11). The most helpful diagnostic
finding
is the acute some
onstrated
of cases
Hydatid
.
lung
in cases
of alcoholism.
disease
than
is
site
traverse
liver
only
five
are
dem-
(11,13).
pancreas
mass. the
involvement
involvement
common
of the
pancreatic
must
filters,
which
of cases
a
Cyst
disease
obstruction
ulcer
bubbles,
Echinococcus
of a cystic
peptic
is gas
in 13%-22%
(10,11). Some authors (12) have reported that abscess is seen more frequently in cases of pancreatitis that result from biliary tract or
a multiocular cyst in the right lobe body ofthe pancreas (small arrows). the complex internal nature of
sand.
thrombosis.
S Abscess A more severe sequela of pancreatitis pancreatic abscess. Infection follows pancreatitis with variable frequency;
seen
cyst anterior
(15%
is a rare
Because
hepatic
(75%
and
para-
pulmonary
of cases)
ofcases)
cause
the
and
are more
than
pancreatic
involvement,
cases
described
in the
with
literature
(14,15).
678
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Ros
et a!
Volume
12
Number
4
Figure
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10.
Microcystic
adenoma.
(a) CT scan
a large pancreatic mass with hyperattenuating, enhanced septations and multiple small cystic spaces. Large calcifications are seen in the center of the tumor (arrows). (b) Photograph of cut surface demonstrates the honeycomb appearance typical of microcystic adenomas with multiple small cysts. Note central fibrous scar (arrows). (c) Photomicrograph (original magnification, x40; hematoxylineosin stain) shows areas of hemorrhage (arrows), which are frequently present in this well-vascularized tumor. Cells lining the cystic spaces have no malignant potential. shows
-
.‘
.
Benign
Neoplasms
Microcystic
C.
adenoma
hypervascular tential US scans
echoic pearance
may
a pseudocyst
CT and tions, may
or
a true
cyst.
may
show
result
region
(Fig
NEOPLASTIC
tumors
neoplasms,
tic
teratoma)
tumors,
that solid
cystic papillary
anaplastic are
only 10%-15% ofall pancreatic and less than 5% of all malignant tumors (16-18).
July
1992
that
were
60
(21).
and
representing
ratios
with
von
areas
with
it is a hypervascular
sified
as a cystic
Friedman
80% or
the in the
older.
et a!
of paThis
tu-
Hippel-Lindau
dis-
of hemorrhage
this
tumor
(Fig
neoplasm.
neoplasm
because
of 1.5(20,21),
is typically
of age with
since
of the
are
10), It is clas-
pancreas,
of its microscopic
appear-
ance. At gross
cys-
years
pocommon
series
(20,21),
associated
cystic
epithe-
cited
approximately
Microscopically,
primarily
or
malignant is more
patients
often
change
carcinoma,
uncommon,
decade
ease
(microcystic
and
8th
noting
penicystic
be seen
with
of these
is associated
neoplasms)
show
age
or
no
tumor
In published
mon
MASSES
cystic
median
tients
Intra-
patients,
(19,20).
(19)
(14,15).
pancreas
mucinous
in female
with
This
material may
mass
of the
and
hal
calcification
cystic
CYSTIC
neoplasms
cell
of the
(16-19).
4.5:1 7th
septacysts.
of contrast
9). Also, the
pancreatic (islet
an-
commonly,
multiple
in enhancement
surrounding
adenoma
More
to daughter
administration
Cystic
a spherical,
US scans corresponding
venous
U
demonstrate
mass if the lesion is unilocular, an apthat is indistinguishable from that of
is a glycogen-containing
tumor
solid that
pathologic
adenoma tumor are
usually
examination,
may with
appear
multiple less
than
a micro-
primarily
as a
small
cystic
2 cm
in size
areas (Fig
10).
neoplasms pancreatic
Ros
et a!
U
RadioGraphics
U
679
a.
b.
Figure
11.
Teratoma
ofthe
pancreas.
(a) US image
of the left upper quadrant shows a large multicystic mass. Note the solid component (arrows). (b) CT scan demonstrates a predominantly cystic mass with thick walls and septations. Areas of fatty attenuation are also seen (arrows). (c) Photograph of cut section shows the complex nature of a pancreatic teratoma with multiple septations, thick wall, and areas of fat.
In up to 20%
tumors contain (19,2 1). Imaging studies may show this tumor as either homogeneously solid, or, more commonly, they may demonstrate a predominantly solid mass with multiple small cysts. Some authors (2 1) have stated that the presence of six or more small cysts within the
central
mass
which
is suggestive
rather
than
Both cystic
of cases,
scar,
of microcystic
mucinous
CT and
these
cystic
US scans
components
of this
also demonstrate a calcified present (Fig 1 1). Both CT show the well-delineated tumors, which are usually tense on T2-weighted MR some central areas of low occasionally
be
seen
a
may calcify
related
neoplasm.
show
the solid
tumor.
CT
and
scans
central scar, if and MR images contour of these markedly hyperinimages, although signal intensity may to scar
Ti-weighted of low
adenoma
formation.
MR images intensity,
signal
has
the tumor to be in cases in
which
the
cases, intense
the areas of hemorrhage appear hyperon Ti-weighted MR images (22).
A cystic
tumor
show except
teratoma
hemorrhaged.
In these
is a slow-growing
Both
US and
CT scans
demonstrate
dominantly cystic characteristics mor, as well as solid components (Fig
1 i).
presence
680
U
RadioGrapbics
U
Ros et a!
tumor
that rarely involves the pancreas; only iO cases have been reported (23). Most of the described cases have had cystic and solid components, such as hair, fat, and calcification (Fig ii) (23).
CT
may
be
helpful
the preof this tuand debris
in showing
the
of fat or calcifications.
Volume
12
Number
4
a.
b. Figure
12.
Cystic
insulinoma
(islet
cell carci-
noma) in a 34-year-old man. (a) US image demonstrates a cystic mass, with acoustic enhancement and without evidence of debris, in the head of the pancreas. (b) CT scan shows a cystic mass that displaces the duodenum laterally. (c) Photograph of a specimen demonstrates the cystic nature of this mass and its intimate attachment to the duodenum. A metallic stent has been placed in the ampulla, indicating its relation to the mass.
C.
Because
it is difficult
a mucinous
cystadenoma
cinoma
or Potentially
. Malignant Neoplasms
Malignant
cystic
or
degenerative
occasionally, necrosis may
components.
a cystic be seen
nonfunctioning
(1,25).
tumors
Tumor
predicted ance (1).
(24-26).
behavior
on the
CT, US, and specific
cystic
(Fig
12).
July
1992
lignant
(19),
basis
that
cannot
neo-
always
has
be
a thick
are
now
tumors potentially
referred
ma-
to as muci-
neoplasms.
dominance, greater
as at least
they
tumors
show
with
a marked
multiple
occurrence
than
diagnosis
of cases. 6th
seen
plasms
tail
with
70%-95%
in the
Most
or
typical
in
age
at
contrasting
with
microcystic
ade-
of these body
pre-
(16,19,21) patients
The
decade,
the older patient nomas (19,2 1). Approximately are
female
studies
in female
80%
is the
(16,18,19,21).
appear-
demonstrate often
to and
and women, are malignant poten-
of histologic
MR images mass
These
cystic
between
a cystadenocar-
all mucinous
regarded
reporting
However,
form corresponding in both functioning
plasms occur equally in men all locally invasive, and have tial
be
These
and
because
should nous
An islet cell carcinoma usually has a very good blood supply, is generally solid, and rarely has
and
to distinguish
neo-
of the
frequently,
these
pancreas
hy-
a nonwall
Ros et a!
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RadioGrapbics
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681
Figure
13.
Mucinous
cystic
neoplasm
in a 56-year-
old woman. (a) US scan demonstrates a large cystic mass containing septations in the tail of the pancreas. (b) Contrast-enhanced CT scan reveals a mass with an attenuation coefficient in the range of that of
water,
with
of its wall. the macrocystic cystic spaces ity
an internal
septation
and mild
Photograph of cut section shows nature of these tumors with large and multiple septations.
povascular tumors are multilocular, may be unilocular. They contain usually have a thick wall, internal solid
papillary
peripheral CT and
nodular-
(c)
excretions,
calcifications US imaging
and, (Figs
studies
but they mucin and septations, occasionally, 13-15)
show
(19).
ular or multilocular nature mucinous cystic neoplasm out septations identifiable
of this mass. is unilocular with imaging
ies,
a pseudocyst
its differentiation
from
C.
the unilocIf a withstudmay
not be possible. US is advantageous to show internal septations, mural nodules, and solid excrescences in the tumor wall (Figs 13, i4).
CT scans
variable
proteinaceous 15c) (22).
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RadioGrapbics
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Ros et a!
after
of contrast
the intravenous material
may
dem-
onstrate enhancement of the septations and peripheral wall (Figs 13-15) (19). MR images show the contents of these cystic masses to be is thought
682
obtained
administration
in signal to
intensity,
be related nature
and
this
variability
to hemorrhage ofthe
Volume
fluid
12
or the
(Fig
i5b,
Number
4
a. Figure
b. 14.
Mucinous
cystic
neoplasm
in a 66-year-old
woman.
(a)
US image
demonstrates
an anechoic
mass in the tail of the pancreas. (b) CT scan also shows the unilocular cystic mass. Except for a mildly irnegulan wall (arrows), this mass was indistinguishable from a pseudocyst and was treated initially with percutaneous drainage. At surgery, the mass proved to be a mucinous cystic tumor.
a.
b. Figure 15. Mucinous cystic neoplasm in a 40year-old woman. (a) CT scan demonstrates a cystic mass in the tail of the pancreas with peripheral calcifications and internal septations (arrowheads). There
is also dilatation
of the pancreatic
duct
(duct-
ectatic mucinous cystic neoplasm). Ti-weighted (300/15) (b) and T2-weighted (2,000/90) (c) MR images of the pancreas demonstrate the cystic mass in the tail of the pancreas (arrows) and the markedly dilated pancreatic duct (arrowheads).
C.
July
1992
Ros et a!
U
RadioGrapbic.s
U
683
d. neoplasm.
C.
Figure
16.
Solid
and papillary
epithelial
(a) CT scan
shows
the solid
(arrows)
and
cystic
nature
of this tumor. (b) T2-weighted MR image shows the capsule as a hypointense peripheral rim (arrow), as well as solid and cystic components of the mass. (C) Photograph of a cut-section specimen shows a whitish, fibrous capsule and papillary excrescences (arrows). (d) Photomicrograph (original magnification, x40; hematoxylin-eosin stain) demonstrates a thick fibrous capsule typical of this tumor (arrows). Both solid and cystic components are also seen. Areas of hemorrhage are frequently noted in this tumor.
Solid
and
are rare
papillary
tumors,
young
women;
grade
malignancies
usually
present,
complex
they and
tumors are
neoplasms
commonly are
(27).
(although,
or solid septations
epithelial
more
seen
considered
to be low-
A thick
internal
in
capsule
is
components
occasionally,
purely
are seen) (Fig 16). not a feature of this
are
cystic
cause of their thick capsule, which is seen as a hypointense rim on T2-weighted MR images (Fig 16). CT and MR images may be helpful in demonstrating Primary
tremely gion
Internal tumor.
Cal-
the lymphoma
rare, of the
as a result
although pancreas
in the re-
uncommonly
seen
retroperitoneal
adenop-
athy (29). This tumor may appear homogeneously hypoechoic on US images, mimicking a cystic appearance (Fig i7). Also, because of internal necrosis, a lymphoma may have cystic
mass.
components.
the
is uncommon
but
may
be
seen
in
tumor
These
tumors
are
well
delineated
be-
Anaplastic
carcinoma
undifferentiated
ant
creas
U
involvement is not
of massive
of hemorrhage. pancreas is cx-
or its capsule (28). CT, US, and MR images show the internal inhomogeneity (cystic and solid) of this large
cification
684
presence of the
RadioGrapbics
U
Ros et a!
cell
and
refers
to aggressive,
neoplasms
and
cell
carcinoma
spindle
or retroperitoneum
(30)
Volume
includes
gi-
of the .
These
12
pan-
tumors
Number
4
a.
b.
Figure
17.
Lymphoma
in a 68-year-old
shows a hypoechoic lesion ture of the mass (arrows).
(arrows)
woman.
similar
(a) US image
to a cystic
mass.
(b)
obtained
in the region of the obtained later shows
CT scan
pancreatic the solid
head na-
a. Figure
18.
Undifferentiated
pancreatic
carcinoma
in a 19-year-old
man.
(a) US image
dominantly cystic, unilocular mass in the tail of the pancreas. A small amount of debris tic mass. (b) CT scan demonstrates a large cystic mass with a thin capsule. The almost these very aggressive tumors is secondary to massive internal necrosis and hemorrhage.
are
usually
large and to massive
secondary
have cystic components internal necrosis and
hemorrhage. US and
CT
cystic
ternal
echoes
scans
mass,
and
demonstrate
frequently
debris
U CONCLUSION Although the postinflammatory
a predomi-
containing
genetic
creatic
in-
(Fig 18).
pseudocyst is overwhelmingly the most common cystic pancreatic mass to be imaged, the radiologist should be aware of the multiple entities, variable prognosis, and clinical significance involved when a cystic mass in the pancreas is encountered. It is especially important to con-
1992
these
with
pancreatic
nantly
July
sider
less
common
syndromes
disease, pseudocyst,
findings and
demonstrates
a pre-
is seen within the totally cystic nature
entities
in patients
associated
with
atypical
cysof
cystic
for pan-
pseudocysts
refrac-
tory
to therapy. In the majority of cases, it is not possible to provide a specific diagnosis because of the substantial overlap of imaging features. However, in the appropriate clinical setting, a rcasonable differential diagnosis can be formulated by combining the findings of CT, US,
and
MR imaging.
Ros et a!
U
RadioGraphics
U
685
In general, tic
masses
pseudocysts that
have
are
a thick
unilocular
pancreatic
cys-
enhanced
wall
and 12.
no gas bubbles. Mucinous cystic neoplasms, as well as anaplastic carcinoma and cystic islet cell tumors, may occasionally have a similar appearance. cysts
Considerations
include
mucinous
cystic
neoplasms,
echinococcus postin.flammatory
crocystic
The presence
of fat in a cystic
ports the diagnosis bles are suggestive
of teratoma, of abscess.
of the pancreas which
cysts
a single
are associated
in other
true
cyst
of the pancreas and, therefore, be followed
by appropriate fluid;
mass
sup-
be
that
is not always percutaneous
of the aspirated
mass
14.
and gas bubMost true cysts with diseases in are seen, although
occasionally
to emphasize
is important
the cystic
organs
may
mi-
cysts, and, pseudocysts.
adenoma,
occasionally,
13.
for multilocular
noted.
a “cystic”
It
mass
15.
16.
17.
a pseudocyst, drainage
cytologic
a biopsy
of the
should
18.
analysis wall
of
may also be necessary.
19.
REFERENCES
U 1.
Robbins
creas.
SL, Cotran
In: Pathologic
RS, Kumar
basis
V.
of disease.
The
pan-
Philadelphia: Saunders, 1984; 960-990. OertelJE, Heffess CS, Oertel YC. Pancreas. ln: Sternberg 55, ed. Diagnostic surgical pathology. NewYork: Raven, 1989; 1057-1093. Mares AJ, Hirsch M. Congenital cysts of the pancreas. J Pediatr Sung 1977; 12:547-552. Shinkhoda A, Mittelstaedt CA. Demonstration ofpancreatic cysts in adult polycystic kidney disease by computed tomography and ultrasound. AJR 1978; 131:1074-1076. Levine E, Collins DL, Horton WA, Schimke RN . CT screening of the abdomen in von Hippel-Lindau disease. AJR 1982; 139:505510. Choyke PL, Filling-Katz MR, Shawker THE, et al. Von Hippel-Lindau disease: radiologic screening for visceral manifestations. Radiology 1990; 174:815-820. Churchill RJ, Cunningham DG, Henkin RE,
2.
3. 4.
5.
6.
7.
Reynes
CJ.
Macrocystic
cysts
9.
acute pancreatitis. Radiol Clin North Am 1989; 27: 19-37. Warshaw AL. Inflammatory masses following acute pancreatitis. Sung Clin North Am 1974;
10.
21.
22.
23.
24.
25.
26.
27.
28.
29.
54:621-635.
11
686
U
RadioGraphics
.
Jeffrey RB, GrendellJH, Improved survival with
U
Ros eta!
Federle MP, et al. early CT diagnosis of
atic abscess. 722-726. Vernacchia Pancreatic
30.
Gastrointest
Sung
Radiol
SM, Miller Gynecol
TA.
Obstet
1987; Pancre-
1979;
149:
FS, Jeffrey RB, Federle MP, et al. abscess: predictive values of early
abdominal CT. Radiology 1987; 162:435-438. Missas 5, Gouliamos A, Kourias E, Kalovidouris A. Primary hydatid disease of the pancneas. Gastrointest Radiol 1987; 12:37-38. Beggs I. The radiology of the hydatid disease. AJR 1985; 145:639-648. Wolfman NT, Ramquist NA, Karstaedt N, Hopkins MB. Cystic neoplasms of the pancreas: CT and Cubilla
sonography. AL, Fitzgerald
AJR 1982; 138:37-41. PJ. Classification
of
pancreatic cancer (nonendocnine) . Mayo Clin Proc 1979; 54:449-458. Mathieu D, Valette PJ, BrunetonJN, PringotJ. Pancreatic cystic neoplasms. Radiol Clin NorthAm 1989; 27:163-176. Friedman AC, LichtensteinJE, Dachman AH. Cystic neoplasms of the pancreas. Radiology 1983; 149:45-50. BuckJL, Hayes WS. Microcystic adenoma of the pancreas. RadioGraphics 1990; 10:313322. Johnson CD, Stephens DM, CharboneaujW, Carpenter HA, Welch TJ. Cystic pancreatic tumors: CT and sonographic assessment. AJR 1988; 151:1133-1138. Minami M, ltai Y, Ohtomo K, Yoshida H, et al. Cystic neoplasm of the pancreas: comparison
ofMR
of the pancreas
in cystic fibrosis demonstrated by multiple radiological modalities. JAMA 1981; 245:7274. Daneman A, Gaskin K, Martin DJ, Cutz E. Pancreatic changes in cystic fibrosis: CT and sonographic appearances. AJR 1983; 141: 653-655. Balthazar EJ. CT diagnosis and staging of
8.
20.
3rd ed.
abscess.
12:26-30. Frey CF, Lindenauer
imaging
with
CT. Radiology
1989;
171:
53-56. Mester M, Trajber HJ, Compton CC, de Camango HSA, de Almedia C, Hoover HC. Cystic teratomas of the pancreas. Arch Sung 1990; 12:127-1278. Pogany AC, Kerlan RK, Karam JH, LeQuesne LP, Ring EJ. Cystic insulinoma. AJR 1984; 142:91-9S2. Thompson NW, Eckhauser FE, Vinik Al, Lloyd RV, Fiddian-Green RG, Strodel WE. Cystic neuroendocrine neoplasms of the pancreas and liver. Ann Sung 1984; 199:158-164. Eelkema EA, Stephens DH, Ward EM, Sheedy PF. CT features of nonfunctioning islet cell carcinoma. AJR 1984; 143:943-948. FarmanJ, Chun-kuo C, Schulze G, TeitcherJ. Solid and papillary epithelial pancreatic neoplasm: an unusual tumor. Gastrointest Radiol 1987; 12:31-34. Choi BI, Kim KW, Han MC, Kim Yl, Kim CW. Solid and papillary epithelial neoplasms of the pancreas: CT findings. Radiology 1988; 166:413-416. Friedman AC, Edmonds PR. Rare pancreatic malignancies. Radiol Clin North Am 1989; 27:177-189. FosalJ. Pancreas and periampullary region. In: Ackerman’s surgical pathology. 7th ed. St Louis: Mosby, 1989; 757-788.
Volume
12
Number
4
Masses
R. Ros,
MD
JenniferE. Hamrick-Turner, Maria V. Chiechi, MD Luis H. Ros, MD Patricia Gallego, MD Sharon S. Burton, MD
Although
the
creas
pseudocyst
found
multiple
is the
at imaging
disease
article mass,
MD2
processes
reviews including
although
makes it generally ing the findings ferential
can
manifest
and
magnetic
the
considerable
impossible from these
diagnosis.
cystic
a cystic
in a similar
This
studies
of imaging
diagnosis, in formulating
of the
pancreas
combina dif-
is not
be followed of the cystic
are
features
always
by cytologic mass may also
necessary. INTRODUCTION
U
Cystic
lesions
in routine cysts tic
of the clinical
arising
an ample
Index 77.32
of the
findings
terms: Pancreas,
I From
the
Institute
goza, Zaragoza, RSNA scientific March Current
e RSNA,
27. Address address:
entities
frequently lesions
the
can
with
of the
radiologist
produce
the
imaging
pancreas should
imaging
are be
aware
appearance
studies pseudothat
of a cys-
a classification
of cystic
masses
in the
pancreas
(Table)
and
a
77. 1 2 1 1
Pancreas,
cysts,
#{149}
77.3
12
Pancreas,
MR.
#{149}
77. 1 2 14
Pancreas,
#{149}
neoplasms,
77.31,
12:673-686
Department
of Radiology,
FL 32610-0374
of Pathology,
cystic
at imaging.
Pancreas, CT, US, 77.1298 1992;
Gainesville,
relatively
most
pancreas. presents
#{149}
detected
of pancreatitis,
of pathologic
article
RadioGraphics
cAne,
are Although
as a consequence
in the
review
pancreas practice.
gamut
mass This
2
manner.
imaging
a specific is helpful
mass
pan-
of the
of the origin of the neoplastic. Computed
overlap
a pseudocyst, percutaneous drainage should analysis of the aspirate. A biopsy of the wall be
of the
be aware
resonance
to render modalities
Because
mass
should
entities by category inflammatory, and
ultrasound, and,
common
radiologists
that
these other congenital,
tomography, presented,
most
studies,
Box
100374,
(P.R.R.,J.E.H.T.,
Washington,
DC (P.R.R.);
Spain (L.H.R.); and Department assembly. Receivedjanuary 30, reprint Department
requests
J. Hulls M.V.C.,
Miller S.S.B.);
Department
Health
of Radiology,
of Radiology, 1992; revision
Center,
Department
Hospital requested
University
of Florida
ofRadiologic Hospital
Pathology,
Miguel
Servet,
Militar, March
Bogota, 5 and
Colombia received
Medical
Center,
Jackson.
College Armed Universidad
of Mcdi. Forces de Zara.
(PG.). From the March 22; accepted
1991
to P.R.R. of Radiology,
University
of Mississippi
1992
673
a.
b.
Figure 1 . Single true cyst of the pancreas in a 56-year-old woman. (a) uation equal to that of water. The mass does not appear enhanced with (arrows). (b) Photograph shows resected tail of the pancreas containing
of the wall demonstrated
U
CONGENITAL
.
Single
A true
the presence
CYSTIC
True
ing
its inner
is derived
from
pancreatic
multilocular
a few
cysts
and
congenital most
have
are
been
seen
in
reported
may be unilocular
usually
microscopic
to 5 cm
computed anechoic,
tomography
range
in size
or
from
uation
Ultrasound (US) and demonstrate an low-attenuating mass with an attencoefficient of 0-20 HU, which is typical
of any
simple
after
RadioGraphics
cyst.
intravenous
material
U
Isolated rare;
an
ducts lin-
(1-3).
True
674
(1).
extremely
although
in adults
(Fig
No
(1).
(CT)
enhancement
administration 1).
U
helped
confirm
the diagnosis
of Cystic
Masses
of a true
cyst.
of the
Cyst
surface are
and
Classification Pancreas
abnormal segmentation of the primitive of the pancreas and has a true epithelium true cysts newborns,
lining
MASSES
of the pancreas
cyst
of epithelial
CT scan shows a cystic mass of attenadministration of contrast material a true cyst. Histologic examination
is seen
of contrast
Congenital cystic masses Single true cyst Multiple true cysts In adult polycystic kidney disease In von Hippel-Lindau disease In cystic fibrosis Inflammatory cystic masses Pseudocyst Abscess Echinococcus cyst Neoplastic cystic masses Benign neoplasms Microcystic adenoma Cystic teratoma Malignant or potentially malignant Islet cell carcinoma Mucinous cystic neoplasms Solid and Lymphoma Anapiastic
Ros et a!
papillary
epithelial
neoplasms
neoplasms
carcinoma
Volume
12
Number
4
Figures
2, 3.
polycystic massive
kidney involvement
(2) Typical
presentation
of adult
disease. CT scan demonstrates of the kidneys and mild involvement of the liver. In the pancreas, only a very small cyst (arrows) is identified. (3) Atypical presentation of adult polycystic kidney disease. (a) US im-
age demonstrates multiple large cysts in the pancreas in a 2-month-old male infant. (b) CT scan also shows with
predominant only
involvement
a few
cysts
in the
of the
kidneys
pancreas,
liver.
and
2.
.
Multiple
True
CT and
Cysts
Most congenital cysts of the pancreas are multiple and are associated with genetic disorders that involve cystic disease in other organs, including adult polycystic kidney disease, von Hippel-Lindau disease, and cystic fibrosis; these cysts may also occur as solitary lesions. Multiple true cysts of the pancreas are seen in approximately polycystic
10% kidney
ofpatients
disease
(4).
with These
usually small and may either diffusely the pancreas or localize to one region. number of cysts varies, but, typically, atic
involvement
is less
seen in the kidneys and pancreatic involvement (Fig 3).
July
1992
than
liver may
the
cystic
adult cysts
are
involve The pancre-
lesions
US findings
are
cysts.
similar
of the individual
to those
Concomitant
hepatic
ment facilitates diagnosis seen in the pancreas. In von Hippel-Lindau in the
kidneys,
spleen, nal cell
for
adrenal
in addition carcinoma
single
and
when disease, glands,
cystic true
renal
involve-
cysts
also
cysts liver,
to the pancreas and microcystic
are
pancreatic
proximately
cysts 30%
(5,6). Readenoma
are demonstrated
of patients
who
seen
and
of the pancreas are also associated with disease (6). In this autosomal dominant der,
are
this disor-
in apundergo
change
(Fig 2). Rarely, predominate
Ros et a!
U
RadioGraphics
U
675
Figures 4, 5. (4) von the tail of the pancreas.
Hippel.Lindau
Note
disease
the surgical
in a 66-year-old
clips
from
woman.
a previous
(a)
CT scan
left adrenalectomy
shows
a cyst
(arrows)
in
for pheochromocytoma
(arrowhead). (b) Ti-weighted MR image (repetition time, 300 msec; echo time, 20 msec [300/20J) shows the cyst as a focal area of low signal intensity (arrows) . (c) Photograph of a cut section of the cyst attached to the tail of the pancreas demonstrates thin walls and several loculi. (5) CT scan demonstrates extensive involvement of the pancreas by multiple cysts in von Hippel-Lindau disease (long solid arrows), which led to diabetes. There is also a renal right kidney (open arrows).
imaging
studies,
indicate
that
but true
data
cysts
cell
obtained are
creas in a greater proportion Imaging studies demonstrate pancreas and other abdominal 5).
Not
infrequently,
calcification which images
these
in the
are
seen
carcinoma
periphery
as acoustic
at autopsy
found
in the
of cases cysts organs cysts
in the
show
(5). in the (Figs
on
U
RadioGraphics
4,
seen,
usually
CT scans HU)
there
findings
replaced echogenic
cysts,
of the in chronic
show
cysts
lesions
parenchyma fat
and
multiple
which
pancreatic
for
di-
ducts,
are
(7).
disease
as low-attenuation
surrounded
surrounding (8).
Rarely,
represent
by pancreatic
-
typical
in the
replacement
(7,8).
in a range relative to 120 HU) (Fig
(-90
cysts
is fatty
parenchyma true
remnants
cal
Ros et a!
Eventually,
(0-25 US
arrows)
pancreatic
lated of
(6).
U
solid
macroscopic
Progressive dilatation of the acini and pancreatic ducts with secondary fibrosis and i-csultant pancreatic atrophy is seen in cystic
676
(short
fibrosis.
on CT scans, shadowing
kidney
of the
pan-
foci
left
a simple
to that of typi6). US shows
cyst.
The
parenchyma
Volume
fatty-
appears
12
Number
4
a.
b.
Figure
6.
Cystic
creas (solid tion (open
fibrosis
arrows). arrows).
in an 1 1-year-old
girl.
(a) CT scan
demonstrates
Note fatty replacement of the pancreatic parenchyma, (b) US image helps confirm the cystic nature of the
a.
a cystic shown mass seen
mass
in the
as an area with CT.
tail of the of low
pan-
attenua-
b.
Figure
Pancreatic pseudocyst. (a) CT scan demonstrates a pseudocyst anterior to the tail of the pancreas. the enhancement of the fibrous wall (arrowheads) of the pseudocyst. (b) Low-power photomicrograph (original magnification, x 40; hematoxylin-eosin stain) shows the fibrous wall of a pseudocyst (anrows) anterior to the tail of the pancreas (T). Note the presence of debris (D ) in the lumen of the pseudocyst, indicating a previous hemorrhage. A vessel (arrowhead) is noted in the fibrous wall.
U
7. Note
INFLAMMATORY
CYSTIC
. Pseudocyst The most common is a pseudocyst, tion 2%-3%
of acute
cystic which
pancreatitis
of all cases
mass
is seen
MASSES
of the pancreas as a complica-
in approximately (9).
These
cystic
structures
are characterized microscopically by a fibrous wall, which develops over a period of approximately 6 weeks (Fig 7) (10). These cystic structures do not have an epithelial lining and are thus pseudocysts (1). The fibrous wall surrounds a collection of pancreatic fluids, cellular debris, and blood (1 1).
July
1992
On US images, pseudocysts are usually welldefined, smooth-walled, anechoic masses, although they may occasionally be multilocular with internal septations. Internal echoes or a fluid-fluid
level
may
be
seen
with
hemor-
rhage or infection. On CT scans, an uncomplicated pseudocyst should appear as a well-dcfined wall or capsule, with a central area of low attenuation and an attenuation coefficient
within
a range
relative
to that
Ros et a!
of water
U
RadioGraphics
U
677
Figure 8. Pancreatic abscess. (a) CT scan demonstrates a low-attenuation pancreas, which contains multiple gas bubbles. The presence ofgas bubbles characteristic of pancreatic abscess. (b) Photograph of a surgical specimen replacing pancreatic parenchyma.
a. Figure
to the tail of the
is the most helpful imaging shows greenish purulent fluid
b. 9.
Hydatid
disease of the liver and pancreas. (a) CT scan shows ofthe liver (large arrows) and a second, smaller multilocular cyst in the (b) Photograph of a specimen from a liver echinococcus cyst demonstrates
the cyst, with
daughter
(Fig
7). Magnetic
may
be
ciated
helpful
cysts
resonance to detect
splenic
and
vein
hydatid
(MR) hemorrhage
studies
cite
percentages
of
1%-21%
imaging or
asso-
Radiologically, in contrast to a pseudocyst, which usually has a distinct wall or capsule, pancreatic abscess generally has indistinct margins (Fig 8) (11). The most helpful diagnostic
finding
is the acute some
onstrated
of cases
Hydatid
.
lung
in cases
of alcoholism.
disease
than
is
site
traverse
liver
only
five
are
dem-
(11,13).
pancreas
mass. the
involvement
involvement
common
of the
pancreatic
must
filters,
which
of cases
a
Cyst
disease
obstruction
ulcer
bubbles,
Echinococcus
of a cystic
peptic
is gas
in 13%-22%
(10,11). Some authors (12) have reported that abscess is seen more frequently in cases of pancreatitis that result from biliary tract or
a multiocular cyst in the right lobe body ofthe pancreas (small arrows). the complex internal nature of
sand.
thrombosis.
S Abscess A more severe sequela of pancreatitis pancreatic abscess. Infection follows pancreatitis with variable frequency;
seen
cyst anterior
(15%
is a rare
Because
hepatic
(75%
and
para-
pulmonary
of cases)
ofcases)
cause
the
and
are more
than
pancreatic
involvement,
cases
described
in the
with
literature
(14,15).
678
U
RadioGrapbics
U
Ros
et a!
Volume
12
Number
4
Figure
.
:,
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., . -.
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-;
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-.,
-
; .;
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p’-’
10.
Microcystic
adenoma.
(a) CT scan
a large pancreatic mass with hyperattenuating, enhanced septations and multiple small cystic spaces. Large calcifications are seen in the center of the tumor (arrows). (b) Photograph of cut surface demonstrates the honeycomb appearance typical of microcystic adenomas with multiple small cysts. Note central fibrous scar (arrows). (c) Photomicrograph (original magnification, x40; hematoxylineosin stain) shows areas of hemorrhage (arrows), which are frequently present in this well-vascularized tumor. Cells lining the cystic spaces have no malignant potential. shows
-
.‘
.
Benign
Neoplasms
Microcystic
C.
adenoma
hypervascular tential US scans
echoic pearance
may
a pseudocyst
CT and tions, may
or
a true
cyst.
may
show
result
region
(Fig
NEOPLASTIC
tumors
neoplasms,
tic
teratoma)
tumors,
that solid
cystic papillary
anaplastic are
only 10%-15% ofall pancreatic and less than 5% of all malignant tumors (16-18).
July
1992
that
were
60
(21).
and
representing
ratios
with
von
areas
with
it is a hypervascular
sified
as a cystic
Friedman
80% or
the in the
older.
et a!
of paThis
tu-
Hippel-Lindau
dis-
of hemorrhage
this
tumor
(Fig
neoplasm.
neoplasm
because
of 1.5(20,21),
is typically
of age with
since
of the
are
10), It is clas-
pancreas,
of its microscopic
appear-
ance. At gross
cys-
years
pocommon
series
(20,21),
associated
cystic
epithe-
cited
approximately
Microscopically,
primarily
or
malignant is more
patients
often
change
carcinoma,
uncommon,
decade
ease
(microcystic
and
8th
noting
penicystic
be seen
with
of these
is associated
neoplasms)
show
age
or
no
tumor
In published
mon
MASSES
cystic
median
tients
Intra-
patients,
(19,20).
(19)
(14,15).
pancreas
mucinous
in female
with
This
material may
mass
of the
and
hal
calcification
cystic
CYSTIC
neoplasms
cell
of the
(16-19).
4.5:1 7th
septacysts.
of contrast
9). Also, the
pancreatic (islet
an-
commonly,
multiple
in enhancement
surrounding
adenoma
More
to daughter
administration
Cystic
a spherical,
US scans corresponding
venous
U
demonstrate
mass if the lesion is unilocular, an apthat is indistinguishable from that of
is a glycogen-containing
tumor
solid that
pathologic
adenoma tumor are
usually
examination,
may with
appear
multiple less
than
a micro-
primarily
as a
small
cystic
2 cm
in size
areas (Fig
10).
neoplasms pancreatic
Ros
et a!
U
RadioGraphics
U
679
a.
b.
Figure
11.
Teratoma
ofthe
pancreas.
(a) US image
of the left upper quadrant shows a large multicystic mass. Note the solid component (arrows). (b) CT scan demonstrates a predominantly cystic mass with thick walls and septations. Areas of fatty attenuation are also seen (arrows). (c) Photograph of cut section shows the complex nature of a pancreatic teratoma with multiple septations, thick wall, and areas of fat.
In up to 20%
tumors contain (19,2 1). Imaging studies may show this tumor as either homogeneously solid, or, more commonly, they may demonstrate a predominantly solid mass with multiple small cysts. Some authors (2 1) have stated that the presence of six or more small cysts within the
central
mass
which
is suggestive
rather
than
Both cystic
of cases,
scar,
of microcystic
mucinous
CT and
these
cystic
US scans
components
of this
also demonstrate a calcified present (Fig 1 1). Both CT show the well-delineated tumors, which are usually tense on T2-weighted MR some central areas of low occasionally
be
seen
a
may calcify
related
neoplasm.
show
the solid
tumor.
CT
and
scans
central scar, if and MR images contour of these markedly hyperinimages, although signal intensity may to scar
Ti-weighted of low
adenoma
formation.
MR images intensity,
signal
has
the tumor to be in cases in
which
the
cases, intense
the areas of hemorrhage appear hyperon Ti-weighted MR images (22).
A cystic
tumor
show except
teratoma
hemorrhaged.
In these
is a slow-growing
Both
US and
CT scans
demonstrate
dominantly cystic characteristics mor, as well as solid components (Fig
1 i).
presence
680
U
RadioGrapbics
U
Ros et a!
tumor
that rarely involves the pancreas; only iO cases have been reported (23). Most of the described cases have had cystic and solid components, such as hair, fat, and calcification (Fig ii) (23).
CT
may
be
helpful
the preof this tuand debris
in showing
the
of fat or calcifications.
Volume
12
Number
4
a.
b. Figure
12.
Cystic
insulinoma
(islet
cell carci-
noma) in a 34-year-old man. (a) US image demonstrates a cystic mass, with acoustic enhancement and without evidence of debris, in the head of the pancreas. (b) CT scan shows a cystic mass that displaces the duodenum laterally. (c) Photograph of a specimen demonstrates the cystic nature of this mass and its intimate attachment to the duodenum. A metallic stent has been placed in the ampulla, indicating its relation to the mass.
C.
Because
it is difficult
a mucinous
cystadenoma
cinoma
or Potentially
. Malignant Neoplasms
Malignant
cystic
or
degenerative
occasionally, necrosis may
components.
a cystic be seen
nonfunctioning
(1,25).
tumors
Tumor
predicted ance (1).
(24-26).
behavior
on the
CT, US, and specific
cystic
(Fig
12).
July
1992
lignant
(19),
basis
that
cannot
neo-
always
has
be
a thick
are
now
tumors potentially
referred
ma-
to as muci-
neoplasms.
dominance, greater
as at least
they
tumors
show
with
a marked
multiple
occurrence
than
diagnosis
of cases. 6th
seen
plasms
tail
with
70%-95%
in the
Most
or
typical
in
age
at
contrasting
with
microcystic
ade-
of these body
pre-
(16,19,21) patients
The
decade,
the older patient nomas (19,2 1). Approximately are
female
studies
in female
80%
is the
(16,18,19,21).
appear-
demonstrate often
to and
and women, are malignant poten-
of histologic
MR images mass
These
cystic
between
a cystadenocar-
all mucinous
regarded
reporting
However,
form corresponding in both functioning
plasms occur equally in men all locally invasive, and have tial
be
These
and
because
should nous
An islet cell carcinoma usually has a very good blood supply, is generally solid, and rarely has
and
to distinguish
neo-
of the
frequently,
these
pancreas
hy-
a nonwall
Ros et a!
U
RadioGrapbics
U
681
Figure
13.
Mucinous
cystic
neoplasm
in a 56-year-
old woman. (a) US scan demonstrates a large cystic mass containing septations in the tail of the pancreas. (b) Contrast-enhanced CT scan reveals a mass with an attenuation coefficient in the range of that of
water,
with
of its wall. the macrocystic cystic spaces ity
an internal
septation
and mild
Photograph of cut section shows nature of these tumors with large and multiple septations.
povascular tumors are multilocular, may be unilocular. They contain usually have a thick wall, internal solid
papillary
peripheral CT and
nodular-
(c)
excretions,
calcifications US imaging
and, (Figs
studies
but they mucin and septations, occasionally, 13-15)
show
(19).
ular or multilocular nature mucinous cystic neoplasm out septations identifiable
of this mass. is unilocular with imaging
ies,
a pseudocyst
its differentiation
from
C.
the unilocIf a withstudmay
not be possible. US is advantageous to show internal septations, mural nodules, and solid excrescences in the tumor wall (Figs 13, i4).
CT scans
variable
proteinaceous 15c) (22).
U
RadioGrapbics
U
Ros et a!
after
of contrast
the intravenous material
may
dem-
onstrate enhancement of the septations and peripheral wall (Figs 13-15) (19). MR images show the contents of these cystic masses to be is thought
682
obtained
administration
in signal to
intensity,
be related nature
and
this
variability
to hemorrhage ofthe
Volume
fluid
12
or the
(Fig
i5b,
Number
4
a. Figure
b. 14.
Mucinous
cystic
neoplasm
in a 66-year-old
woman.
(a)
US image
demonstrates
an anechoic
mass in the tail of the pancreas. (b) CT scan also shows the unilocular cystic mass. Except for a mildly irnegulan wall (arrows), this mass was indistinguishable from a pseudocyst and was treated initially with percutaneous drainage. At surgery, the mass proved to be a mucinous cystic tumor.
a.
b. Figure 15. Mucinous cystic neoplasm in a 40year-old woman. (a) CT scan demonstrates a cystic mass in the tail of the pancreas with peripheral calcifications and internal septations (arrowheads). There
is also dilatation
of the pancreatic
duct
(duct-
ectatic mucinous cystic neoplasm). Ti-weighted (300/15) (b) and T2-weighted (2,000/90) (c) MR images of the pancreas demonstrate the cystic mass in the tail of the pancreas (arrows) and the markedly dilated pancreatic duct (arrowheads).
C.
July
1992
Ros et a!
U
RadioGrapbic.s
U
683
d. neoplasm.
C.
Figure
16.
Solid
and papillary
epithelial
(a) CT scan
shows
the solid
(arrows)
and
cystic
nature
of this tumor. (b) T2-weighted MR image shows the capsule as a hypointense peripheral rim (arrow), as well as solid and cystic components of the mass. (C) Photograph of a cut-section specimen shows a whitish, fibrous capsule and papillary excrescences (arrows). (d) Photomicrograph (original magnification, x40; hematoxylin-eosin stain) demonstrates a thick fibrous capsule typical of this tumor (arrows). Both solid and cystic components are also seen. Areas of hemorrhage are frequently noted in this tumor.
Solid
and
are rare
papillary
tumors,
young
women;
grade
malignancies
usually
present,
complex
they and
tumors are
neoplasms
commonly are
(27).
(although,
or solid septations
epithelial
more
seen
considered
to be low-
A thick
internal
in
capsule
is
components
occasionally,
purely
are seen) (Fig 16). not a feature of this
are
cystic
cause of their thick capsule, which is seen as a hypointense rim on T2-weighted MR images (Fig 16). CT and MR images may be helpful in demonstrating Primary
tremely gion
Internal tumor.
Cal-
the lymphoma
rare, of the
as a result
although pancreas
in the re-
uncommonly
seen
retroperitoneal
adenop-
athy (29). This tumor may appear homogeneously hypoechoic on US images, mimicking a cystic appearance (Fig i7). Also, because of internal necrosis, a lymphoma may have cystic
mass.
components.
the
is uncommon
but
may
be
seen
in
tumor
These
tumors
are
well
delineated
be-
Anaplastic
carcinoma
undifferentiated
ant
creas
U
involvement is not
of massive
of hemorrhage. pancreas is cx-
or its capsule (28). CT, US, and MR images show the internal inhomogeneity (cystic and solid) of this large
cification
684
presence of the
RadioGrapbics
U
Ros et a!
cell
and
refers
to aggressive,
neoplasms
and
cell
carcinoma
spindle
or retroperitoneum
(30)
Volume
includes
gi-
of the .
These
12
pan-
tumors
Number
4
a.
b.
Figure
17.
Lymphoma
in a 68-year-old
shows a hypoechoic lesion ture of the mass (arrows).
(arrows)
woman.
similar
(a) US image
to a cystic
mass.
(b)
obtained
in the region of the obtained later shows
CT scan
pancreatic the solid
head na-
a. Figure
18.
Undifferentiated
pancreatic
carcinoma
in a 19-year-old
man.
(a) US image
dominantly cystic, unilocular mass in the tail of the pancreas. A small amount of debris tic mass. (b) CT scan demonstrates a large cystic mass with a thin capsule. The almost these very aggressive tumors is secondary to massive internal necrosis and hemorrhage.
are
usually
large and to massive
secondary
have cystic components internal necrosis and
hemorrhage. US and
CT
cystic
ternal
echoes
scans
mass,
and
demonstrate
frequently
debris
U CONCLUSION Although the postinflammatory
a predomi-
containing
genetic
creatic
in-
(Fig 18).
pseudocyst is overwhelmingly the most common cystic pancreatic mass to be imaged, the radiologist should be aware of the multiple entities, variable prognosis, and clinical significance involved when a cystic mass in the pancreas is encountered. It is especially important to con-
1992
these
with
pancreatic
nantly
July
sider
less
common
syndromes
disease, pseudocyst,
findings and
demonstrates
a pre-
is seen within the totally cystic nature
entities
in patients
associated
with
atypical
cysof
cystic
for pan-
pseudocysts
refrac-
tory
to therapy. In the majority of cases, it is not possible to provide a specific diagnosis because of the substantial overlap of imaging features. However, in the appropriate clinical setting, a rcasonable differential diagnosis can be formulated by combining the findings of CT, US,
and
MR imaging.
Ros et a!
U
RadioGraphics
U
685
In general, tic
masses
pseudocysts that
have
are
a thick
unilocular
pancreatic
cys-
enhanced
wall
and 12.
no gas bubbles. Mucinous cystic neoplasms, as well as anaplastic carcinoma and cystic islet cell tumors, may occasionally have a similar appearance. cysts
Considerations
include
mucinous
cystic
neoplasms,
echinococcus postin.flammatory
crocystic
The presence
of fat in a cystic
ports the diagnosis bles are suggestive
of teratoma, of abscess.
of the pancreas which
cysts
a single
are associated
in other
true
cyst
of the pancreas and, therefore, be followed
by appropriate fluid;
mass
sup-
be
that
is not always percutaneous
of the aspirated
mass
14.
and gas bubMost true cysts with diseases in are seen, although
occasionally
to emphasize
is important
the cystic
organs
may
mi-
cysts, and, pseudocysts.
adenoma,
occasionally,
13.
for multilocular
noted.
a “cystic”
It
mass
15.
16.
17.
a pseudocyst, drainage
cytologic
a biopsy
of the
should
18.
analysis wall
of
may also be necessary.
19.
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Volume
12
Number
4
