AJR 2005; 184:521-525
© American Roentgen Ray Society
Sonographic Pitfalls in the Diagnosis of Enteric Duplication Cysts
G. Cheng1,
Don Soboleski1,
Alan Daneman2,
D. Poenaru3 and
D. Hurlbut4
1 Department of Diagnostic Radiology, Queen's University, Kingston General
Hospital, 76 Stuart St., Kingston, ON K7L 2V7, Canada.
2 Department of Diagnostic Imaging, The Hospital for Sick Children, Toronto, ON,
Canada.
3 Department of Surgery, Queen's University, Kingston General Hospital,
Kingston, ON, Canada.
4 Department of Pathology and Molecular Medicine, Queen's University, Kingston
General Hospital, Kingston, ON, Canada.
Received January 26, 2004;
accepted after revision March 24, 2004.
Address corerspondence to D. Soboleski
(daas{at}post.queensu.ca).
Abstract
OBJECTIVE. The sonographic double wall sign has been well described
in the literature and is often the cornerstone in suggesting the diagnosis of
an enteric duplication cyst. We report two cases with this sign that were
erroneously diagnosed as enteric cysts and a third case without this
sonographic feature that proved to be a duplication cyst. Histologic analysis
of the specimens helps explain the cause of the sonographic pitfalls.
CONCLUSION. The potential sonographic visualization of the split
hypoechoic muscularis propria layer or identification of all five layers will
increase the specificity in making the sonographic diagnosis of duplication
cyst.
Introduction
Enteric duplication cysts are rare congenital anomalies arising anywhere
along the alimentary tract. As the name suggests, enteric duplication cysts
are defined by their histologic appearance, which mimics that of the native
gastrointestinal tract possessing an inner mucosa–submucosa layer
surrounded by an outer smooth-muscle layer
[1]. The double wall or
"muscular rim" sign has been suggested to be characteristic of
duplication cysts
[2–4].
The characteristic sonographic appearance consists of an inner hyperechoic rim
correlating to the mucosa–submucosa and an outer surrounding hypoechoic
layer reflecting muscularis propria. Less often, five sonographic layers are
identified, reflecting superficial mucosa, deep mucosa, submucosa, muscularis
propria, and serosa. This finding has been seen both in vivo
[5] and in vitro
[6].
Investigators have described cases of a torted ovarian cyst
[7] and Meckel's diverticulum
[8] showing a false-positive
double wall sign; however, histologic correlation is not available. We report
two more entities mimicking enteric cysts on sonography and help explain the
appearance by histologic analysis. A third case of a duplication cyst that did
not exhibit the "gut-signature" sign also is illustrated with
histologic correlation depicting another sonographic pitfall. Splitting of the
muscle layer that results in a Y configuration, as seen on an in vitro
specimen from the pathology department bank, may prove more specific in
establishing this diagnosis of duplication cyst if it can be detected in
vivo.
Subjects and Methods
Case 1
A fetal cystic abdominal mass lying between umbilicus and bladder was
identified on a routine antenatal sonography examination. The fetus was born
at term by spontaneous vaginal delivery without complication. Physical
examination revealed a small mass palpable under the umbilicus. Follow-up
sonograms obtained at 2 weeks and 1 month revealed a 3.3-cm complex cystic
mass adjacent to multiple loops of bowel and the right ovary. The left ovary
was unremarkable. The cyst contained a central echogenic avascular component,
thought to be hemorrhage. The cyst wall consisted of an inner hyperechoic rim
that was surrounded by a thin hypoechoic layer, resulting in a double wall
sign (Fig. 1A,
1B,
1C).
View larger version (155K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 1A. —Case 1: 6-week-old girl with mesenteric cyst. Physical
examination revealed small mass palpable under umbilicus. Sonogram depicts
echogenic granulation layer (arrowheads) with surrounding thin
hypoechoic fibrous band (arrows). Note hyperechoic debris
(asterisk) in cyst lumen.
|
|
View larger version (104K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 1B. —Case 1: 6-week-old girl with mesenteric cyst. Physical
examination revealed small mass palpable under umbilicus. Intraoperative
photograph illustrates cyst is separate from small bowel (SB).
|
|
View larger version (110K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 1C. —Case 1: 6-week-old girl with mesenteric cyst. Physical
examination revealed small mass palpable under umbilicus. Histologic
photomicrograph depicts layer of granulation tissue with focal
microcalcification (arrowheads) overlying outer wall of fibrous
connective tissue (arrows).
|
|
The patient was taken to surgery with a diagnosis of enteric duplication
cyst with a differential diagnosis of meconium peritonitis or pseudocyst,
urachal remnant cyst, and ovarian cyst or teratoma.
Case 2
A 15-year-old nulligravida girl presented with severe right lower quadrant
pain and associated nausea and vomiting. The patient was otherwise healthy and
had undergone no surgeries previously. Her last menstrual period was 2 weeks
prior. On physical examination, a palpable, mobile suprapubic mass was noted.
A sonogram revealed a 7.0-cm predominantly cystic mass with some internal
echoes located in the right adnexa. The right ovary was not identified on
sonography. The cyst wall was composed of a hyperechoic inner rim surrounded
by a hypoechoic layer, consistent with the double-wall sign. A CT scan showed
a complex cystic mass containing heterogeneous densities (fluid, fat, and
calcification). The fat component of the mass was distributed in the
periphery, whereas the fluid component was central. The peripheral rim of fat
correlated with the hyperechoic rim seen on sonography (Fig.
2A,
2B,
2C).
View larger version (118K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 2A. —Case 2: 15-year-old nulligravida girl with cystic teratoma.
Patient presented with severe right lower quadrant pain and associated nausea
and vomiting. Sonogram depicts cyst (C) with hyperechoic inner rim
(arrowheads) and outer hypoechoic wall (arrows). B =
bladder.
|
|
View larger version (113K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 2B. —Case 2: 15-year-old nulligravida girl with cystic teratoma.
Patient presented with severe right lower quadrant pain and associated nausea
and vomiting. CT scan depicts cyst (C) with low-attenuating (fat) inner ring
(arrowhead) and higher-attenuating outer wall (white arrow).
Note focus of calcification (black arrow).
|
|
View larger version (123K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 2C. —Case 2: 15-year-old nulligravida girl with cystic teratoma.
Patient presented with severe right lower quadrant pain and associated nausea
and vomiting. Histologic photomicrograph shows cyst mucosa with squamous
epithelial lining (arrowheads) and outer fibromuscular wall
(arrows).
|
|
The patient was taken to surgery, and wedge resection of an ovarian cystic
neoplasm was performed via open laparotomy.
Case 3
A 3-year-old girl presented with a 3-week history of nausea and diarrhea
and a palpable left upper quadrant abdominal mass. The patient was afebrile
with a normal WBC count of 9.1 x 109/L and no left shift. The
patient was healthy previously and was born at term by spontaneous vaginal
delivery. A sonogram revealed a complex intraperitoneal cystic mass with a
thick irregular hypoechoic wall that was inseparable from the distal
transverse colon near the splenic flexure. A CT scan revealed a complex cystic
mass with indistinct margins inseparable from the stomach, colon, and anterior
pancreas. Stranding into adjacent fat with loss of fascial planes, supporting
an inflammatory nature, also was detected.
The patient was taken to the operating room for laparotomy with a
differential diagnosis of complicated duplication cyst, torted mesenteric
cyst, Meckel's diverticulum, or neoplasm with necrosis. At surgery,
inflammatory changes involving the lesser sac, distal transverse mesocolon,
and greater curve of the stomach were noted. A frozen section of the cystic
mass was obtained, and it was consistent with a duplication cyst with colonic
connection. Segmental resection of the distal transverse colon and colonic
duplication cyst followed without complication.
Results
Case 1
Pathologic examination of the excised cyst showed a wall composed of
fibrous connective tissue without a smooth-muscle layer. The wall was
thickened in areas by organizing granulation tissue situated on the inner
luminal aspect. The cyst contained old blood, and no residual epithelial
lining was identified. Focal mural calcification was present. The pathologic
features were consistent with a mesenteric cyst.
Case 2
Pathologic examination of the specimen from surgery showed findings of a
mature cystic teratoma. The cyst, containing sebaceous material and skin
elements with hair, was visible on gross examination. Histopathology showed
variable cyst epithelial lining (squamous and intestinal-type glandular
epithelia) supported by fibrous and focally neural tissue.
Case 3
Cultures of the cystic fluid grew multiple gram-negative bacteria,
compatible with enteric origin. Pathology revealed a cyst lined with acute
inflammatory exudate, overlying granulation tissue, and an inflamed fibrous
connective tissue wall (Fig.
3A,
3B,
3C). No epithelial or mucosal
lining was seen. However, an area of division and focal partial sharing of the
colonic muscularis propria layer was identified. The pathologic appearance was
that of a secondarily infected duplication cyst with the mucosal layer lost to
ulceration.
View larger version (112K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 3A. —Case 3: 3-year-old girl with infected duplication cyst.
Patient presented with 3-week history of nausea and diarrhea and palpable left
upper quadrant abdominal mass. Sonogram depicts cyst (C) with thick,
ill-marginated hypoechoic wall (white arrows). Note small bright
echoes (black arrow) related to air in cyst. B = bowel.
|
|
View larger version (112K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 3B. —Case 3: 3-year-old girl with infected duplication cyst.
Patient presented with 3-week history of nausea and diarrhea and palpable left
upper quadrant abdominal mass. CT scan depicts complex cyst (C) with irregular
hypoattenuating wall (arrows). Wall margins are indistinct, and
increased attenuation within adjacent fat and loss of fascial planes support
inflammatory nature.
|
|
View larger version (156K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 3C. —Case 3: 3-year-old girl with infected duplication cyst.
Patient presented with 3-week history of nausea and diarrhea and palpable left
upper quadrant abdominal mass. Histologic photomicrograph shows collapsed
duplication cyst lumen (C). Note lack of inner mucosal layer in cyst.
Surrounding wall shows inflammatory changes with inner granulation tissue
(arrows) partially obscuring underlying shared smooth-muscle layer. B
= bowel.
|
|
Discussion
Sonography plays a critical role in the workup of pediatric abdominal
masses and often dictates further management. Well described in the literature
is the double wall or muscular rim sign, which refers to the appearance of a
cyst mimicking the gastrointestinal tract with an echogenic inner margin
corresponding to mucosa surrounded by a hypoechoic rim of tissue representing
the smooth-muscle layer. Identification of this sign on sonography of an
abdominal mass has been regarded as characteristic of an enteric duplication
cyst
[3–5,
9,
10].
Pitfalls in relying on this double-layered appearance in the diagnosis of
enteric duplication cysts have been described. Researchers have described a
sonographic artifact that may mimic the double wall sign of enteric
duplication cysts [9]. This
artifact was seen on nearly one half of the nonenteric cysts on retrospective
analysis of preoperative sonograms. The artifact was described as focal with
sharp edges and disappeared with transducer angulation. Histologic analyses of
these cysts were not described.
We describe three cases with histologic correlation in which reliance on
the double-layered appearance led to both false-positive and false-negative
diagnostic information. In case 1, an echogenic inner wall is the result of
areas of dystrophic calcification within a layer of granulation tissue. The
more hypoechoic surrounding layer reflects a band of fibrous connective tissue
and results in the "pseudo gut-signature" sign (Fig.
1A,
1B,
1C) of this mesenteric cyst. In
case 2, there are two explanations for the sonographic appearance. A thin
layer of fat within the periphery of this ovarian teratoma, as noted on CT,
results in a hyperechoic inner "wall" on sonography. The presence
of enteric-type architecture noted on a histologic section also could
contribute to this appearance, although separation from the fat layer was not
evident on sonography. The surrounding hypoechoic layer is again the result of
a fibrous wall and results in a pseudo gut-signature sign (Fig.
2A,
2B,
2C). The calcification within
the wall of the cyst was overlooked on sonography, likely mistaken for
adjacent bowel gas. The presence of calcification and hyperechoic soft tissue
would have raised the suspicion of a possible teratoma.
Case 3 represents an enteric duplication cyst complicated by infection. The
inner mucosal layer was eroded, which explains the lack of a hyperechoic inner
wall on sonography, as has been described in a previous study
[3]. The irregular thickened
hypoechoic wall corresponds to exudate, granulation tissue, and inflamed
connective tissue (Fig. 3A,
3B,
3C). Air pockets visualized on
the sonogram are believed to result from communication of the cyst with native
bowel lumen. In this case, the sonographic appearance also raised the concern
for neoplasm with necrosis, although the CT features supported an inflammatory
nature.
In all three cases, histologic analysis helps explain both the
"pseudo double wall" sign (cases 1 and 2) and the lack of the
expected sonographic features of an enteric duplication cyst (case 3).
Review of the histology of a true duplication cyst reveals splitting of the
shared hypoechoic muscularis propria layer (Fig.
4A,
4B,
4C), resulting in a Y
configuration. In vitro sonographic interrogation of the duplication cyst
specimen from the pathology department bank also depicts this splitting of the
muscle layer. This Y configuration, if visualized in vivo, may prove more
reliable in establishing the diagnosis of an enteric duplication cyst.
View larger version (134K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 4B. —Intestinal duplication cyst specimen from 5-month-old girl.
Histologic photomicrograph of boxed area from gross specimen (A) shows
convergence of cyst and small-bowel walls: duplication cyst mucosa
(arrowhead), shared muscularis propria (upper left arrow),
and mucosa of native ileum (upper right arrow). Asterisks =
muscularis propria course, C = duplication cyst lumen, lower arrow = gut
lumen.
|
|
View larger version (127K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 4C. —Intestinal duplication cyst specimen from 5-month-old girl.
Sonogram of specimen depicts echogenic cyst mucosa (arrowheads) and
hypoechoic shared muscularis (white arrows). Note thicker native
ileal mucosa (black arrow). Asterisks show course of muscularis
propria. Gut lumen and walls are enveloped by ultrasound gel.
|
|
In conclusion, this report expands the differential diagnosis and helps
explain the appearance of the pseudo double wall or muscular rim sign of
abdominal cystic masses. Sonographic visualization of the split hypoechoic
muscularis propria layer or identification of all five layers increases the
specificity in making the sonographic diagnosis of duplication cyst.
References
- Ros PR, Olmsted WW, Moser RP Jr, Dachman AH, Hjermstad BH, Sobin
LH. Mesenteric and omental cysts: histologic classification with imaging
correlation. Radiology1987; 164:327
–332[Abstract/Free Full Text]
- Segal SR, Sherman NH, Rosenberg HK, et al. Ultrasonographic
features of gastrointestinal duplications. J Ultrasound
Med 1994;13:863
–870[Abstract]
- Kangarloo H, Sample WF, Hansen G, Robinson JS, Sarti D. Ultrasonic
evaluation of abdominal gastrointestinal tract duplication in children.
Radiology1979; 131:191
–194[Abstract]
- Moccia W, Astacio J, Kaude J. Ultrasonographic demonstration of
gastric duplication in infancy. Pediatr Radiol1981; 11:52
–54[Medline]
- Simonovsky V. Jejunal duplication cyst displaying peristalsis and a
five-layered appearance of the wall: a preoperative ultrasound diagnosis.
Eur Radiol 1996;6:153
–155[Medline]
- Kimmey MB, Martin RW, Haggitt RC, Wang KY, Franklin DW, Silverstein
FE. Histologic correlates of gastrointestinal ultrasound images.
Gastroenterology1989; 96:433
–441[Medline]
- Godfrey H, Abernethy L, Boothroyd A. Torsion of an ovarian cyst
mimicking enteric duplication cyst on transabdominal ultrasound: two cases.
Pediatr Radiol1998; 28:171
–173[Medline]
- Gallego-Herrero C, del Pozo-Garcia G, Marin-Rodriguez C, Ibarrola
de Andres C. Torsion of a Meckel's diverticulum: sonographic findings.
Pediatr Radiol1998; 28:599
–601[Medline]
- Barr LL, Hayden CK Jr, Stansberry SD, Swischuk LE. Enteric
duplication cysts in children: are their ultrasonographic wall characteristics
diagnostic? Pediatr Radiol1990; 20:326
–328[Medline]
- Richards D, Langham M, Anderson D. The prenatal sonographic
appearance of enteric duplication cysts. Ultrasound Obstet
Gynecol 1996;7:17
–20[Medline]
CiteULike 
Complore 
Connotea 
Del.icio.us 
Digg 
Reddit 
Technorati What's this?
This article has been cited by other articles:
|
|
|
|
 
J. Sutcliffe and M. Munden
Sonographic diagnosis of multiple gastric duplication cysts causing gastric outlet obstruction in a pediatric patient.
J. Ultrasound Med.,
September 1, 2006;
25(9):
1223 - 1226.
[Full Text]
[PDF]
|
|
|
Top
Abstract
Introduction
