DOI:10.2214/AJR.07.2808
AJR 2008; 190:406-412
© American Roentgen Ray Society
CT of Serous Cystadenoma of the Pancreas and Mimicking Masses
Hyoung Jung Kim1,
Dong Ho Lee1,
Young Tae Ko1,
Joo Won Lim1,
Hyun Cheol Kim2 and
Kyoung Won Kim3
1 Department of Radiology, Kyung Hee University Medical Center, 1, Hoegi-dong,
Dongdaemun-gu, Seoul 130-702, Korea.
2 Department of Radiology, East–West Neo Medical Center, Kyung Hee
University, Seoul, Korea.
3 Departments of Radiology, University of Ulsan College of Medicine and Asan
Medical Center, Seoul, Korea.
Received December 21, 2006;
accepted after revision August 10, 2007.
Address correspondence to H. J. Kim
(radhjkim{at}khu.ac.kr).
CME
This article is available for CME credit. See
www.arrs.org
for more information.
Abstract
OBJECTIVE. The purpose of this article is to illustrate the varied
CT appearances of serous cystadenoma of the pancreas and of masses that mimic
serous cystadenoma.
CONCLUSION. Serous cystadenomas of the pancreas have a wide range of
CT findings. Familiarity with the varied CT appearances and awareness of the
diagnostic limitations of CT are important for accurate diagnosis and
management of serous cystadenoma of the pancreas.
Keywords: CT • cystadenoma • hepatobiliary imaging • pancreas • pancreatic neoplasms
Introduction
Cystic neoplasms of the pancreas, including serous cystadenoma, are being
recognized with greater frequency because of the increasingly widespread use
of abdominal CT. Only rare instances of the malignant form, serous
cystadenocarcinoma, have been reported in the literature
[1]. Most patients who have
serous cystadenoma do not require resection unless they are symptomatic.
Pancreatic serous cystadenoma can have a varied appearance on CT. The
morphologic patterns of serous cystadenoma can be classified as polycystic,
honeycomb, and oligocystic [2,
3]. Serous cystadenomas are
typically solitary but may be multiple in von Hippel-Lindau disease, causing
an appearance of disseminated involvement
[4]. They can have the
appearance of a solid mass [5].
The appearance of serous cystadenoma can therefore overlap with a variety of
other types of pancreatic pathology. The spectrum of appearances of pancreatic
serous cystadenoma, with an emphasis on CT, will be presented.
Polycystic Pattern
The polycystic pattern is the most common appearance of serous cystadenoma;
it occurs in approximately 70% of cases
[2]. This pattern consists of a
bosselated (marked by numerous rounded protuberances) collection of cysts that
usually number more than six. Each cyst may range from a few millimeters to 2
cm in size. This pattern shows two important morphologic features: external
lobulation and a central scar. A central scar with or without a stellate
pattern of calcification on CT occurs in up to 30% of cases, and it is
considered strongly suggestive of serous cystadenoma
[6] (Fig.
1A,
1B).
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Fig. 1A —67-year-old woman with serous cystadenoma, polycystic
pattern. Pancreatic phase CT axial (A) and coronal (B)
reformations show cystic lesion (arrows) in tail of pancreas. Cyst
has many loculi, thin septa, external lobulation, and central scar with
stellate calcification (arrowhead).
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Fig. 1B —67-year-old woman with serous cystadenoma, polycystic
pattern. Pancreatic phase CT axial (A) and coronal (B)
reformations show cystic lesion (arrows) in tail of pancreas. Cyst
has many loculi, thin septa, external lobulation, and central scar with
stellate calcification (arrowhead).
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Intraductal papillary mucinous neoplasm, branch duct type, and mucinous
cystic neoplasm are cystic neoplasms that can have a polycystic appearance
similar to that of serous cystadenomas. Communication with the pancreatic
duct, pancreatic duct dilatation, and a pleomorphic cystic shape are imaging
features that are suggestive of intraductal papillary mucinous neoplasm
[7,
8] (Fig.
2A,
2B). A smooth surface without
lobulation, a relatively thick enhancing wall, and peripheral calcifications
are imaging features that suggest mucinous cystic neoplasm
[6,
9]
(Fig. 3).
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Fig. 2A —61-year-old woman with intraductal papillary mucinous
neoplasm, branch duct type. Portal venous phase CT coronal reformations show
grapelike cystic lesion (arrows) in head of pancreas. Cystic
components have varied appearance. Note thin communication
(arrowhead, A) between pancreatic duct and cystic lesion.
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Fig. 2B —61-year-old woman with intraductal papillary mucinous
neoplasm, branch duct type. Portal venous phase CT coronal reformations show
grapelike cystic lesion (arrows) in head of pancreas. Cystic
components have varied appearance. Note thin communication
(arrowhead, A) between pancreatic duct and cystic lesion.
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Fig. 3 —38-year-old woman with mucinous cystadenoma. Portal venous
phase CT coronal reformation shows round cystic lesion (arrows) in
tail of pancreas. Lesion has multiple internal septa (arrowheads).
Note smooth contour without lobulated margin.
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Honeycomb Pattern
The honeycomb pattern of serous cystadenoma is seen in approximately 20% of
cases [2]. This pattern
consists of numerous tiny cysts that mimic a honeycomb or a sponge. These tiny
cysts may be poorly depicted as individual cysts on CT (Fig.
4A,
4B). On unenhanced CT, the
honeycomb pattern may appear as a well-marginated lesion with soft-tissue or
mixed attenuation, depending on the size of the cysts and the amount of
fibrous tissue. Such lesions may show moderate to strong enhancement (Fig.
5A,
5B,
5C).
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Fig. 4A —46-year-old man with serous cystadenoma, honeycomb pattern.
Portal venous phase CT coronal reformation shows low-attenuation mass
(arrows) in tail of pancreas. Mass has slightly higher attenuation
than that of water in stomach (S). Note multiple thin internal septa
(arrowheads). Internal honeycomb pattern is difficult to
appreciate.
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Fig. 5A —49-year-old woman with serous cystadenoma, honeycomb pattern.
Pancreatic phase CT scan shows small inhomogeneous mass (arrows) in
head of pancreas. Anterior portion of tumor (arrowhead) shows high
enhancement and other portions show intermediate to low enhancement.
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Fig. 5B —49-year-old woman with serous cystadenoma, honeycomb pattern.
Portal venous phase CT scan shows inhomogeneous mass (arrows).
Portion that had high enhancement in A now shows decreased enhancement
(arrowhead). Honeycomb pattern is difficult to identify on this CT
image.
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Islet cell tumor and solid pseudopapillary tumor are examples of solid
tumors in which the spectrum of appearances, including cystic changes and
necrosis, can overlap with those of serous cystadenoma. Unlike small islet
cell tumors, which show strong homogeneous enhancement during the pancreatic
phase, large islet cell tumors often show heterogeneous enhancement
[10]. Ringlike enhancement due
to central areas of necrosis or cystic degeneration in islet cell tumor
(Fig. 6) may be helpful in
excluding serous cystadenoma, which shows inhomogeneous moderate to strong
enhancement. A thick tumor capsule and findings suggestive of hemorrhage favor
the diagnosis of a solid pseudopapillary tumor rather than serous cystadenoma
[11].
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Fig. 6 —20-year-old woman with islet cell tumor. Pancreatic phase CT
shows characteristic ring enhancement pattern (arrows). Note central
low attenuation compatible with probable necrosis (arrowhead).
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Solid pseudopapillary tumor should be considered whenever a solid, cystic,
or mixed pancreatic tumor is identified in a young female patient
[11]. However, solid
pseudopapillary tumor with a minimal cystic component or intratumoral
hemorrhage can be difficult to differentiate from the honeycomb pattern of
serous cystadenoma on CT (Figs.
7 and
8A,
8B).
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Fig. 7 —27-year-old woman with solid pseudopapillary tumor. Portal
venous phase CT scan shows large mass (arrows) in head of pancreas.
Mass shows inhomogeneous enhancement, which is suggestive of necrosis or
hemorrhage.
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Fig. 8A —57-year-old woman with serous cystadenoma, honeycomb pattern.
Portal venous phase CT scan shows hypervascular mass in tail of pancreas.
Central fibrous scar (arrowhead) is seen as low density.
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Fig. 8B —57-year-old woman with serous cystadenoma, honeycomb pattern.
Sonogram obtained in similar plane to that of A shows large echogenic
mass posterior to stomach (S). Note increased through-transmission
(arrows) posterior to mass. Pathologic specimen (not shown) showed
solid-appearing mass with multiple small cysts and central fibrous scar. Small
hemorrhage was present at medial aspect of mass.
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Further evaluation using MRI can be helpful for patients with a suspicious
honeycomb pattern of serous cystadenoma on CT. On MRI, the tiny cysts of
serous cystadenomas can be seen as numerous discrete foci with bright signal
intensities on the T2-weighted images (Figs.
4A,
4B,
4C and
5A,
5B,
5C). Sonography may have an
additional role here. The honeycomb pattern of serous cystadenoma can have the
sonographic appearance of a homogeneous, hyperechoic mass with posterior
acoustic enhancement (Fig. 8A,
8B).
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Fig. 4C —46-year-old man with serous cystadenoma, honeycomb pattern.
Photograph of cut surface of specimen shows central scar (arrowhead)
and innumerable tiny cysts, similar to those of T2-weighted image
(B).
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Macrocystic or Oligocystic Pattern
The macrocystic or oligocystic pattern is relatively uncommon, occurring in
less than 10% of patients [2].
It may appear as a unilocular cyst or it may contain fewer large (> 2 cm)
cysts. The differential diagnosis of a macrocystic or oligocystic lesion
includes pseudocyst, mucinous cystic neoplasm, and solid pseudopapillary
tumor. External lobulation favors the diagnosis of serous cystadenoma over
pseudocyst [12](Figs.
9A,
9B and
10). Features that favor the
diagnosis of serous cystadenoma over mucinous cystadenoma or
cystadenocarcinoma include a lobulated contour, lack of a prominent thickened
peripheral wall, and location in the head of the pancreas
[12]
(Fig. 11). If solid
pseudopapillary tumor is associated with massive intratumoral hemorrhage and
necrosis, it can potentially mimic the appearance of a unilocular cyst.
However, imaging features such as a thick wall and hemorrhage in the cystic
component strongly favor solid pseudopapillary tumor over serous cystadenoma
[11] (Fig.
12A,
12B). Solid pseudopapillary
tumor should be considered whenever a cystic tumor is present in a young
female patient [11].
Unenhanced CT is helpful in identifying the high density of hemorrhage. For
the macrocystic form of serous cystadenoma consisting of several large cysts
or loculi, the presence of a lobulated contour favors serous cystadenoma over
mucinous cystic neoplasm (Fig.
13A,
13B).
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Fig. 9A —44-year-old woman with unilocular serous cystadenoma. Portal
venous phase CT scan shows unilocular cystic lesion surrounded by
imperceptible wall. Lesion shows lobulated margin (arrow).
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Fig. 9B —44-year-old woman with unilocular serous cystadenoma.
Photograph of cut surface of specimen shows unilocular cystic lesion with
lobulated margin (arrow), characteristic of serous cystadenoma.
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Fig. 10 —53-year-old man with pancreatic pseudocyst. Portal venous
phase CT scan shows unilocular cyst surrounded by prominent enhancing wall
(arrow) in tail of pancreas. Note infiltration (arrowheads)
in peripancreatic fat, which is suggestive of pancreatitis.
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Fig. 11 —47-year-old woman with mucinous cystadenoma. Portal venous
phase CT scan shows round cystic lesion. Medial wall of cystic lesion
(arrow) is slightly thickened. Lobulated margin is not seen.
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Fig. 12A —11-year-old girl with solid pseudopapillary tumor. Unenhanced
CT scan shows round lesion (arrows) in tail of pancreas. Lesion
appears heterogeneous with central area of high attenuation
(arrowhead), which is suggestive of hemorrhage.
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Fig. 12B —11-year-old girl with solid pseudopapillary tumor. On portal
venous phase CT scan, unilocular cystic lesion surrounded by enhancing wall
(arrows) is noted. Pathologic specimen (not shown) showed cystic
lesion filled with hemorrhage.
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Fig. 13A —55-year-old man with oligocystic serous cystadenoma. Portal
venous phase CT scan shows cystic lesion (arrow) in tail of pancreas,
consisting of several loculi and subtle enhancing septa. Note lobulated
contour of cystic lesion.
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Although a lobulated contour is a specific feature of serous cystadenoma,
it may be overlooked on the initial CT evaluation (Fig.
14A,
14B). Thin-section CT,
endoscopic sonography, or MRI may have an additional role here for a more
accurate depiction of the morphologic characteristics of a pancreatic cystic
neoplasm.
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Fig. 14A —44-year-old man with unilocular serous cystadenoma. Portal
venous phase CT scan shows unilocular cystic lesion surrounded by thin
nonenhancing wall (arrow) in body of pancreas. Subtle lobulated
margin (arrowhead) was missed on initial evaluation.
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Disseminated Variant
Serous cystadenomas are usually single lesions; disseminated pancreatic
involvement is rare. The presence of multiple lesions is rare but can be seen
in patients with von Hippel-Lindau disease (Fig.
15A,
15B). Von Hippel-Lindau
disease is an autosomal dominant condition with CNS and retinal
hemangioblastomas, visceral cysts, pheochromocytomas, and renal cell
carcinoma. It has been reported that 56% of patients with von Hippel-Lindau
disease have pancreatic lesions
[4]. These pancreatic lesions
included cysts, serous cystadenomas, and islet cell tumors. The combined
presence of these lesions in a patient with von Hippel-Lindau disease can
cause the appearance of marked, diffuse pancreatic involvement with poor
delineation of one lesion type from another.
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Fig. 15A —41-year-old woman with serous cystadenoma, disseminated
variant. Serial images from portal venous phase CT show multiple cysts
replacing entire pancreas. Right nephrectomy was performed 5 years earlier
because of renal cell carcinoma. Surgical clips (arrow, B) are
seen in right renal fossa.
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Fig. 15B —41-year-old woman with serous cystadenoma, disseminated
variant. Serial images from portal venous phase CT show multiple cysts
replacing entire pancreas. Right nephrectomy was performed 5 years earlier
because of renal cell carcinoma. Surgical clips (arrow, B) are
seen in right renal fossa.
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Solid Variant
There are few case reports in the literature of solid serous adenoma of the
pancreas, a rare variant of serous cystadenoma. It is formed by the cells that
line the cysts of other forms of serous cystadenoma but with an absence of any
cystic spaces on histopathology
[5]. It has been reported on CT
as having the appearance of an enhancing solid pancreatic mass. Given the
reported findings, it would probably be impossible to differentiate a solid
serous adenoma from small islet cell tumors and metastatic renal cell
carcinomas on CT [13].
Solid-appearing areas of the more common serous cystadenomas, seen on CT or on
gross histologic specimen, are not rare. However, they usually consist of tiny
cysts on microscopic examination
[14].
Tumor Growth Rates
If the diagnosis of serous cystadenoma is unreliable on the initial
cross-sectional imaging, then follow-up imaging can be another solution. It
has been reported that small serous cystadenoma (< 4 cm in diameter) had a
slow growth rate of about 0.12 cm per year
[15]. However, considering the
cystic nature of theses tumors, the tumor volumes and doubling time may have
less applicability for serous cystadenomas than for relatively solid tumors
such as adenocarcinoma (Fig.
16A,
16B).
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Fig. 16B —44-year-old woman with serous cystadenoma. Seven months
later, cystic lesion (arrow) shows increase in diameter on pancreatic
phase CT scan. Small amount of hemorrhage was present in several loculi of
serous cystadenoma on pathologic specimen (not shown).
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Management
It has been suggested that patients with incidentally discovered
simple-appearing pancreatic cystic lesions smaller than 2 cm without any
imaging characteristics suggestive of an invasive tumor be observed
[16]. If there is high
certainty of a diagnosis of serous cystadenoma on the basis of CT or MRI
features, and the patient is asymptomatic (i.e., no findings of jaundice or
pain), then lesions 2 cm or larger can be also potentially managed by
observation. However, if there is uncertainty regarding the diagnosis of
serous cystadenoma based on cross-sectional imaging, then further evaluation
can be obtained with endoscopic sonography and fine-needle aspiration
[16]. Surgical resection is
likely to be considered if aspiration contains mucin, mucinous epithelium,
high levels of carcinoembryonic antigen, or malignant cells because these
findings are strongly suggestive of a mucinous neoplasm
[3].
Conclusion
Serous cystadenomas can have a varied appearance on CT; their appearances
can overlap with those of other cystic or solid pancreatic masses. Familiarity
with the wide range of CT appearances and awareness of the diagnostic
limitations of CT are important for the differential diagnosis and management
of these lesions. MDCT, including multiplanar reformations, facilitates
characterization of pancreatic serous cystadenoma and mimicking lesions. MRI
can be a helpful adjunct.
References
- Yoshimi N, Sugie S, Tanaka T, et al. A rare case of serous
cystadenocarcinoma of the pancreas. Cancer1992; 69:2449
–2453[CrossRef][Medline]
- Sarr MG, Murr M, Smyrk TC, et al. Primary cystic neoplasms of the
pancreas: neoplastic disorders of emerging importance—current
state-of-the-art and unanswered questions. J Gastrointest
Surg 2003; 7:417
–428[CrossRef][Medline]
- Sahani DV, Kadavigere R, Saokar A, et al. Cystic pancreatic
lesions: a simple imaging-based classification system for guiding management.
Radio-Graphics 2005;25
:1471
–1484[Abstract/Free Full Text]
- Hough DM, Stephens DH, Johnson CD, Binkovitz LA. Pancreatic lesions
in von Hippel-Lindau disease: prevalence, clinical significance, and CT
findings. AJR 1994;162
:1091
–1094[Abstract/Free Full Text]
- Perez-Ordonez G, Naseem A, Lieberman PH, Klimstra DS. Solid serous
adenoma of the pancreas: the solid variant of the serous cystadenoma?
Am J Surg Pathol 1996;20
:1401
–1405[CrossRef][Medline]
- Curry CA, Eng J, Horton KM, et al. CT of primary cystic pancreatic
neoplasms: can CT be used for patient triage and treatment?
AJR 2000; 175:99
–103[Abstract/Free Full Text]
- Fukukura Y, Fujiyoshi F, Sasaki M, Inoue H, Yonezawa S, Nakajo M.
Intraductal papillary mucinous tumors of the pancreas: thin-section helical CT
findings. AJR 2000;174
: 441–447[Abstract/Free Full Text]
- Kim SY, Lee JM, Kim SH, et al. Macrocystic neoplasms of the
pancreas: CT differentiation of serous oligocystic adenoma from mucinous
cystadenoma and intraductal papillary mucinous tumor.
AJR 2006; 187:1192
–1198[Abstract/Free Full Text]
- Demos TC, Psniak HV, Harmath C, Olson MC, Aranha G. Cystic lesions
of the pancreas. AJR 2002;179
:1375
–1388[Free Full Text]
- Sheth S, Hruban RK, Fishman EK, et al. Helical CT of islet cell
tumors of the pancreas: typical and atypical manifestations.
AJR 2002; 179:725
–730[Free Full Text]
- Choi JY, Kim MJ, Kim JH, et al. Solid pseudopapillary tumor of the
pancreas: typical and atypical manifestations. AJR2006; 187: 481;
[web]W178–W186[CrossRef]
- Cohen-Scali F, Vilgrain V, Brancatelli G, et al. Discrimination of
unilocular macrocystic serous cystadenoma from pancreatic pseudocyst and
mucinous cystadenoma with CT: initial observations.
Radiology 2003;228
: 727–733[Abstract/Free Full Text]
- Yamaguchi M. Solid serous adenoma of the pancreas: a solid variant
of serous cystadenoma or a separate disease entity. J
Gastroenterol 2006; 41:178
–179[CrossRef][Medline]
- Takeshita K, Kutomi K, Takada K, et al. Unusual imaging appearances
of pancreatic serous cystadenoma: correlation with surgery and pathologic
analysis. Abdom Imaging 2005;30
: 610–615[CrossRef][Medline]
- Tseng JF, Warshaw AL, Sahani DV, et al. Serous cystadenoma of the
pancreas: tumor growth rates and recommendations for treatment. Ann
Surg 2005; 242:413
–419[Medline]
- Handrich SJ, Hough DM, Fletcher JG, Sarr MG. The natural history of
the incidentally discovered small simple pancreatic cyst: long-term follow-up
and clinical implications. AJR 2005;184
: 20–23[Abstract/Free Full Text]
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J.-Y. Choi, M.-J. Kim, J. Y. Lee, J. S. Lim, J. J. Chung, K. W. Kim, and H. S. Yoo
Typical and Atypical Manifestations of Serous Cystadenoma of the Pancreas: Imaging Findings With Pathologic Correlation
Am. J. Roentgenol.,
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Abstract
Introduction
