AJR 2004; 183:1393-1396
© American Roentgen Ray Society
Symptomatic Perirenal Serous Cysts of Müllerian Origin Mimicking Renal Cysts on CT
Thomas X. Minor1,
Benjamin M. Yeh2,
Andrew E. Horvai3,
Harrison M. Abrahams1,
Maxwell V. Meng1 and
Marshall L. Stoller1
1 Department of Urology, University of California, San Francisco, San Francisco,
CA 94143-0738.
2 Department of Radiology, University of California, San Francisco, 505
Parnassus Ave., Box 0628, M-372, San Francisco, CA 94143-0628.
3 Department of Pathology, University of California, San Francisco, San
Francisco, CA 94143-0738.
Received December 19, 2003;
accepted after revision February 26, 2004.
Address correspondence to B. M. Yeh
(benyeh{at}itsa.ucsf.edu).
Abstract
OBJECTIVE. Our aim was to describe the clinical presentation, CT
appearance, and management of a series of symptomatic perirenal serous cysts
of müllerian origin, confirmed by laparoscopic resection.
CONCLUSION. Perirenal serous cysts of müllerian origin are
uncommon lesions that may present as large symptomatic perirenal cystic masses
mimicking exophytic renal cysts on CT. Serous cyst of müllerian origin
should be considered in the differential diagnosis when CT reveals a large
solitary perirenal cyst in a woman with flank or abdominal pain or both.
Laparoscopic resection may be an effective treatment of such cysts.
Introduction
Serous cysts of müllerian origin, also called cystadenomas,
occur in both pre- and postmenopausal women
[1,
2]. Although these lesions
usually form within or near the ovaries, they may occur elsewhere in the
abdomen [1]. However, the
occurrence of peritoneal serous cysts of müllerian origin arising from
the peritoneum separate from the ovary and mimicking renal cysts has not, to
our knowledge, been previously described. The purpose of this article is to
report the clinical presentation, CT appearance, and management of a series of
symptomatic perirenal serous cysts of müllerian origin mimicking solitary
exophytic benign renal cysts.
Materials and Methods
Patients
This was a retrospective single-institution study approved by our committee
on human research. Written consent was not required. From 2002 to 2003, three
patients were identified with a preoperative radiographic diagnosis of a
solitary symptomatic exophytic renal cyst of the lower pole. Each patient
subsequently underwent transperitoneal laparoscopic exploration with intact
resection of the cyst. The cyst wall and fluid underwent complete
histopathologic and cytologic evaluation. The medical records and radiographic
images were reviewed. Clinical, surgical, and histopathologic findings were
tabulated.
CT Technique
Before surgery (n = 3) and after surgery (n = 1),
patients underwent routine examination on an MDCT scanner (LightSpeed, GE
Healthcare) with 5-mm slice thickness, 27-mm/sec table speed, and a 1.0/sec
gantry rotation time. Images were obtained in one or two suspended
breath-holds from the diaphragm to the ischial tuberosities with a scanning
delay of 70 sec after the administration of a 150-mL IV bolus of iohexol
(Omnipaque 350, Nycomed Amersham). All patients received 800 mL of oral
diatrizoate meglumine (Hypaque, Nycomed Amersham). Multiplanar subvolume
maximum-intensity-projection and volume-rendered reformations were obtained on
a dedicated workstation (Advantage Windows 4.0, GE Healthcare).
Image Interpretation
Two urologists and one attending radiologist with subspecialty training in
abdominal imaging reviewed all CT images by consensus on a PACS workstation
(AGFA). For each preoperative CT scan, the maximal diameter of the perirenal
cyst and the CT attenuation were measured. The wall of the cyst was recorded
as visible or imperceptible (not distinct from the cyst contents) on CT, and
the cyst wall contour was recorded as smooth or irregular. The presence or
absence of septa or mural nodules within each cyst was recorded. Septa were
defined as linear or bandlike opacities within the cyst, and mural nodules
were defined as focal soft-tissue opacities along the walls of the cyst. The
CT texture of the cyst contents was recorded as homogeneous or heterogeneous.
The kidneys were evaluated for local deformity (flattening or concavity of the
renal contour) or the "claw" sign (concavity of the renal contour
with renal parenchyma cupping the cyst) or both. The presence or absence of
additional renal parenchymal lesions was also recorded. For the single
postoperative CT scan, recurrence of fluid collections or development of other
abnormalities was recorded.
Immunohistochemistry
Tissue was stained using antibodies recognizing calretinin,
carcinoembryonic antigen (CEA-m), and keratin. Immunohistochemical analysis
was performed using standard techniques on 4-µm paraffin-embedded sections.
These sections were heated; deparaffinized; heated in citrate buffer; blocked
for endogenous peroxidase, avidin, and biotin; and then incubated with
antibodies, washed, and developed using the labeled streptavidin-biotin (LSAB
kit, DAKO).
Results
Clinical symptoms, patient demographics, and CT findings are summarized in
Table 1. All patients were
premenopausal women with a mean age of 39 years. None of the patients had a
family history of renal cystic disease or prior urologic evaluation or
surgery. All three masses had imperceptible walls with smooth cyst wall
contours and homogeneous internal texture on CT (Figs.
1A,
1B,
2A,
2B,
3A,
3B,
3C,
3D). No internal septa, mural
nodules, or other renal lesions were seen.
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Fig. 1A. --31-year-old woman with peritoneal serous cyst of müllerian
origin. IV contrast-enhanced axial CT scan shows round homogeneous
fluid-density mass (arrow) deforming lower pole of right kidney.
|
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Fig. 3D. --46-year-old woman with peritoneal serous cyst of müllerian
origin. Photomicrograph of histopathologic specimen shows intense staining of
epithelium, which did not show staining with calretinin or carcinoembryonic
antigen-m (not shown). (antikeratin immunoperoxidase, x400)
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All patients underwent laparoscopic renal exploration and intended
decortication for their presumed renal cysts. At surgery, all cysts originated
solely from the peritoneum, separate from the kidney, ovary, or other
peritoneal organs. The cysts were excised intact with no intraoperative
complications. Robotic laparoscopic assistance was used during one operation.
Two of the three patients were pain-free at 6 and 9 months postoperatively,
whereas the third patient had persistent intermittent symptoms of pelvic pain
after 13 months. Repeat CT in this latter patient at 10 months failed to
reveal recurrence of a cystic mass or other significant abnormality.
Pathologic and cytologic findings were all benign (Figs.
3A,
3B,
3C,
3D). The walls of all three
cysts were composed of loose fibroconnective tissue with occasional findings
of chronic inflammation. Two cysts showed simple columnar epithelium
(Fig. 3C) that was strongly
keratin positive (Fig. 3D) but
negative for CEA-m and calretinin; both mucinous and serous differentiation
was observed. In one patient, the epithelium showed areas of cellular
ovarian-type stroma, whereas another had cilia. On the basis of these
histopathologic and surgical findings, these two cysts were diagnosed as
simple serous cysts of müllerian origin. The third cyst was composed of a
fibrous capsule without epithelial lining. No malignant features or renal
parenchyma was noted.
Discussion
We present three cases of symptomatic perirenal serous cysts of
müllerian origin that mimicked renal cysts on CT. These patients shared
similar clinical and radiologic findings. All patients were premenopausal
women with abdominal CT showing solitary cysts abutting the lower pole of the
right kidney.
Serous cysts of müllerian origin occurring separate from the ovaries
and fallopian tubes are rare
[1,
2] and are histologically
distinct from peritoneal inclusion cysts or benign cystic mesotheliomas
[3]. Serous cysts of
müllerian origin most commonly occur in or adjacent to the ovaries
[2] but have been described
elsewhere in the abdomen, including the retroperitoneum
[1]. These masses may show
serous or mucinous differentiation and may contain septa or nodules
[2]. To our knowledge, we
report the first cases of serous cysts of müllerian origin mimicking
renal cysts on CT.
In our series, the misdiagnosis of these cysts as being renal in origin was
likely due in part to the high prevalence of renal cysts in the general
population. Renal cysts have a prevalence of 20% by 40 years old and 33% after
60 years old [4,
5]. Although most renal cysts
remain small and clinically silent, a minority enlarge and may result in
abdominal, flank, or pelvic pain
[6,
7]. Aspiration alone may
temporarily relieve pain, but renal cysts frequently recur with continuation
or resurgence of symptoms [4].
Patients with such findings are increasingly being referred, as were our
patients, for primary laparoscopic exploration or resection. Laparoscopic
treatment may definitively relieve symptoms
[6,
7], and depending on the
location of the renal cyst and preference, the surgeon can use a
transperitoneal or retroperitoneal approach.
Although renal contour deformity was seen on CT in one of the three
patients in our series, the claw sign was not identified in any patient. The
absence of a claw sign may be helpful for distinguishing a renal from nonrenal
cystic mass. Furthermore, none of our patients had other lesions in either
kidney on CT nor did they report a history of renal disease. These findings
suggest that when a large isolated cystic mass is identified adjacent to the
kidney, the possibility that such a cyst is nonrenal in origin should be
entertained, particularly for exophytic renal lesions of the lower pole in
women. Nevertheless, most of these lesions are renal in origin. If it is
suspected that a cyst is extrarenal, sonography may be helpful in evaluating
independent motion of the kidney from the cyst with respiration
[8]. Differentiation of
nonrenal from renal cysts may change surgical management because nonrenal
cysts have a higher risk of malignancy, so cyst resection rather than
marsupialization or drainage alone is recommended for nonrenal cysts
[1].
On identification of a large cyst adjacent to and not clearly arising from
the kidney, entities other than a renal or peritoneal inclusion cyst should be
considered. Retroperitoneal cysts are unusual and are often due to pancreatic
pseudocysts, but additional possible causes include primary retroperitoneal
hydatid cysts, mesothelial cysts
[9], bronchogenic cysts
(particularly if located superior to the kidney)
[10], lymphoceles,
lymphangiomas [11], and
tailgut cysts [12]. Other
cysts may originate from the ovary, appendix, or mesentery.
In summary, we present a series of patients with large symptomatic
perirenal serous cysts of müllerian origin that mimicked exophytic renal
cysts on CT. Serous cysts of müllerian origin should be considered in the
differential diagnosis when evaluating a woman with flank or abdominal pain or
both, with CT revealing a large solitary perirenal cyst. Laparoscopic
treatment may be effective for such cysts.
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Abstract
Introduction
