Cases Ultrasound Daniel
--.
Case
Macek,
MD
#{149} S.
Zafar
ofthe
of the H. Jafri,
Day
Day1 #{149} Beatrice
MD
L. Madrazo,
I
.-.
I
4...
-
MD
___
---
S.-’-
.
.‘,
‘
--: ,
.
--
i’.
I.,
[
p,._
:
‘
.
:-::
-:
-j-
J
.:_
-‘--
1
‘
.. .
-
a.
b.
Figure
1.
Transverse
U HISTORY A 71-year-old abdominal ing
was
(US),
pain,
terms:
RadloGraphics
Appendix.
From the Department 1992; revision requested
1992
nausea, hospital
radiography, (CT)
1992;
I
November
a 3-week
anorexia, to the
abdominal
e RSNA,
with
pain localized to the The patient underwent
tomography
Index
ofthe
right
lower
quadrant
U woman
admitted
increasing quadrant.
sonograms
(Figs
751.317
history
of
and
vomit-
because
of
right lower ultrasound and
computed
#{149} Mucocek.
and
slightly
oblique
to
it
(b).
FINDINGS
US revealed
a complex
echogenic
mass
with
bright echogenic areas at gravity-dependent portions (Fig 1). The mass had linear vertical echogenic areas and anechoic areas. Despite the presence of the mass and significant discomfort experienced by the patient, no definite
1-4).
(a)
signs
of associated
inflammation
could
be
751.317
12:1247-1249 of Diagnostic September
Radiology. William Beaumont Hospital. 1 and received September 10; accepted
360 1 W 1 3 Mile Rd. Royal Oak. September 10. Address reprint
MI 48073. requests
Received to B.L.M.
August
26,
1992
Macek
et al
U
RadioGraphics
U
1247
2.
3.
Figures 2-4. (2) Abdominal radiograph shows a faintly calcified mass in the right lower quadrant (arrows). Surgical clips are from previous right nephrectomy. (3) Image from a barium enema study shows a smoothly marginated filling
defect at the base of the cecum (arrows) . (4) Enhanced CT scan shows the mass with rim calcification (arrow). Its relationship to the is established by demonstration the adjacent terminal ileum head).
cecum of (arrow-
found. Radiography demonstrated a sue mass in the right iliac fossa, with curvilinear eggshell calcification (Fig barium enema examination revealed ing
of the
appendix,
with
mass
soft-tisa faint 2). The non.fill-
effect
at the
cecum medially (Fig 3). CT demonstrated a 3.5-cm mass of soft-tissue attenuation with calcification in its wall (Fig 4). CT-guided necdie aspiration yielded “jelly.” DIAGNOSIS:
Mucocele
of the
appendix.
U DISCUSSION Mucocele of the appendix is a rare entity found in 0.2%-0.3% of appendectomies. Mucocele has traditionally been used to refer to appendiceal lesions with one or more of the following features: dilatation of the lumen, alteration of the mucosal lining, hypersecre-
tion of mucus, and occasional extension outside the appendix (so-called pseudomyxoma peritonei) . Its pathogenesis remains controversial. Traditionally, it was considered a cystic dilatation of the lumen secondary to obstruction. More recently, mucoceles have been classified into three distinct entities: mucosal hyperplasia, an innocuous hyperplastic process; mucinous cystadenoma, a benign neoplasm; and mucinous cystadenocarcinoma, a malignant tumor (1). Acute or chronic right lower quadrant pain is the 25%
U
RadioGraphics
U
Macek
et 31
common are
age of presentation to-male predominance tients
may
have
clinical
complaint.
About
asymptomatic.
The
mean
is 55 years, with a femaleof 4: 1 (2). Rarely, pa-
symptoms
related
to second-
ary infection or intussusception. There has been reported association between mucocele and other tumors. In patients with mucoceles, the risk of adenocarcinoma of the colon is six times
1248
most
of patients
greater
than
that
for
the
general
Volume
popula-
12
Number
6
tion (3). In addition, an association may exist between appendiceal mucocele and mucinsecreting tumors of the ovary (4). Treatment of benign cystadenoma and mucosal hyperplasia is simple appendectomy. Because predicting the underlying cause merely by inspecting the serosal surface of a dilated appendix may be difficult, some suggest that a frozen section examination should be done while the abdomen is open (5). If a cystadenocarcmnoma is found, a right colectomy is mandatory. Complications include rupture
of the
pseudomyxoma
mucocele, peritonei,
development torsion
with
of
Radiographically, mass,
a mucocele possibly
with
is seen peripheral
cur-
varies,
corresponding
Pizzimbono
CA, et al.
Muco-
AJ, Heinonen R, Lauren P. Benign and malignant mucocele of the appendix. Acta
Aho
3.
Chir Scand 1973; 139:392-400. WolffM, Ahmed N. Epithelial
the vermiform papillary
4.
appendix.
adenoma,
neoplasms
of
II. Cystadenoma,
and
adenomatous
polyps
ofthe appendix. Cancer 1976; 37:25 11-2522. Young RH, Gilks CB, Scully RE. Mucinous tumors of the appendix associated with mucinous tumors of the ovary and pseudomyxoma peritonei. AmJ Surg Pathol 1991; 15:4 15429.
5.
Pagnozzi
JA, Mueller
sal hyperplasia
appendix:
SC, Cioroiu
(mucocele)
report
M.
of the
of a case.
Muco-
vermiform
Dis Colon
Rectum
1988; 3 1:735-737.
6.
Woodruff lignant
to the
ceration. CT appearance also varies. The contents of the cystic mass, with or without wall calcification or septations, range from near-water attenuation to soft-tissue attenuation, depending on the presence of mucin or debris within the mucocele (12). Pseudomyxoma peritonei
1992
E, RosaiJ,
2.
(8). US appearance
Higa
sal hyperplasia, mucinous cystadenoma, and mucinous cystadenocarcmnoma of the appendix: a re-evaluation of appendiceal mucocele. Cancer 1973; 32:1525-1541.
as a
contents of the mucocele, which may be thin and watery or thick and gelatinous. Patterns include a purely cystic lesion with anechoic fluid, a hypoechoic mass containing fine internal echoes, and a complex mass with highlevel echoes (9,10). Gravity-dependent echoes represent layering of protein macroaggregates or mnspissated mucoid material (10). A typical pattern ofvertical linear echoes, described as a “vortical fold,” can simulate mntussusception, although this rarely complicates mucoceles. Calcification of the wall is difficult to recognize with US (1 1). Polypoid excrescence may be seen projecting mntraluminally from the wall, probably representing proliferation of hyperplastic epithelium. Internal, thin septations have been seen with US, as well as variable degrees of mucosal atrophy and ul-
November
REFERENCES
gan-
vilinear calcification. A barium enema examination classically demonstrates nonfilling of the appendix and an extrinsic or submucosal mass at the cecal tip with intact overlying mucosa
U 1.
grene and hemorrhage, and herniation into the cecum causing varying degrees of bowel obstruction. Of these, pseudomyxoma peritonei is the most likely (6). Preoperative diagnosis of mucocele is helpful to the surgeon in that careful mobilization may reduce the possibility of rupture, peritoneal contamination, and development of pseudomyxoma peritonei (7). Pseudomyxoma peritonei results in a severe inflammatory response and ascites and is associated with malignant mucoceles. soft-tissue
may also be demonstrated, with fibrotic reaction adjacent to the mucocele and ascites and with associated scalloping of the margins of the liver and other organs (13). Gallium scintigraphy may demonstrate intense early uptake, despite the lack of inflammatory cells, possibly due to the acid mucopolysaccharide component of the mucus, which has an affinity to the analogue ferric iron (14).
7.
R, McDonald cystic
JR.
Benign
and
tumors
of the appendix. 1940; 7 1:750-755.
Gynecol Obstet Koster LH. Symptomatic mucocele appendix diagnosed preoperatively. Surg
1974;
ma-
Surg
of the Am J
127:582-584.
8.
Euphrat EJ. Roentgen features of mucocele of the appendix. Radiology 1947; 48:113-
9.
Sandler trasonic
117.
MA, PearlbergJL, and
of mucocele Med 1984;
Madrazo
BL.
UI-
computed tomographic features of the appendix. J Ultrasound 3:97-99.
10.
Parulekar
1 1.
diseases of the appendix. J Ultrasound Med 1983; 2:59-64. Shaane P, Ruud TE, HaffnerJ. Ulti-asonographic features of mucocele of the appendix. JCU 1988; 16:584-587.
12.
Callen tion
5G.
PW.
Ultrasonographic
Computed
of abdominal
tomographic
and
13.
ology 1979; 131:171-175. Madwed D, Mindeizun cocele of the appendix:
14.
Seshul
1992;
finding
pelvic
in
evalua-
abscesses.
R, Jeffrey RBJr. image findings.
Radi-
MuAJR
159:69-72.
MB, Coulam
CM.
Pseudomyxoma
peritonei: computed tomography raphy. AJR 1981; 136:803-806.
Macek
et 31
U
and
RadioGraphics
sonog-
U
1249
--.
Case
Macek,
MD
#{149} S.
Zafar
ofthe
of the H. Jafri,
Day
Day1 #{149} Beatrice
MD
L. Madrazo,
I
.-.
I
4...
-
MD
___
---
S.-’-
.
.‘,
‘
--: ,
.
--
i’.
I.,
[
p,._
:
‘
.
:-::
-:
-j-
J
.:_
-‘--
1
‘
.. .
-
a.
b.
Figure
1.
Transverse
U HISTORY A 71-year-old abdominal ing
was
(US),
pain,
terms:
RadloGraphics
Appendix.
From the Department 1992; revision requested
1992
nausea, hospital
radiography, (CT)
1992;
I
November
a 3-week
anorexia, to the
abdominal
e RSNA,
with
pain localized to the The patient underwent
tomography
Index
ofthe
right
lower
quadrant
U woman
admitted
increasing quadrant.
sonograms
(Figs
751.317
history
of
and
vomit-
because
of
right lower ultrasound and
computed
#{149} Mucocek.
and
slightly
oblique
to
it
(b).
FINDINGS
US revealed
a complex
echogenic
mass
with
bright echogenic areas at gravity-dependent portions (Fig 1). The mass had linear vertical echogenic areas and anechoic areas. Despite the presence of the mass and significant discomfort experienced by the patient, no definite
1-4).
(a)
signs
of associated
inflammation
could
be
751.317
12:1247-1249 of Diagnostic September
Radiology. William Beaumont Hospital. 1 and received September 10; accepted
360 1 W 1 3 Mile Rd. Royal Oak. September 10. Address reprint
MI 48073. requests
Received to B.L.M.
August
26,
1992
Macek
et al
U
RadioGraphics
U
1247
2.
3.
Figures 2-4. (2) Abdominal radiograph shows a faintly calcified mass in the right lower quadrant (arrows). Surgical clips are from previous right nephrectomy. (3) Image from a barium enema study shows a smoothly marginated filling
defect at the base of the cecum (arrows) . (4) Enhanced CT scan shows the mass with rim calcification (arrow). Its relationship to the is established by demonstration the adjacent terminal ileum head).
cecum of (arrow-
found. Radiography demonstrated a sue mass in the right iliac fossa, with curvilinear eggshell calcification (Fig barium enema examination revealed ing
of the
appendix,
with
mass
soft-tisa faint 2). The non.fill-
effect
at the
cecum medially (Fig 3). CT demonstrated a 3.5-cm mass of soft-tissue attenuation with calcification in its wall (Fig 4). CT-guided necdie aspiration yielded “jelly.” DIAGNOSIS:
Mucocele
of the
appendix.
U DISCUSSION Mucocele of the appendix is a rare entity found in 0.2%-0.3% of appendectomies. Mucocele has traditionally been used to refer to appendiceal lesions with one or more of the following features: dilatation of the lumen, alteration of the mucosal lining, hypersecre-
tion of mucus, and occasional extension outside the appendix (so-called pseudomyxoma peritonei) . Its pathogenesis remains controversial. Traditionally, it was considered a cystic dilatation of the lumen secondary to obstruction. More recently, mucoceles have been classified into three distinct entities: mucosal hyperplasia, an innocuous hyperplastic process; mucinous cystadenoma, a benign neoplasm; and mucinous cystadenocarcinoma, a malignant tumor (1). Acute or chronic right lower quadrant pain is the 25%
U
RadioGraphics
U
Macek
et 31
common are
age of presentation to-male predominance tients
may
have
clinical
complaint.
About
asymptomatic.
The
mean
is 55 years, with a femaleof 4: 1 (2). Rarely, pa-
symptoms
related
to second-
ary infection or intussusception. There has been reported association between mucocele and other tumors. In patients with mucoceles, the risk of adenocarcinoma of the colon is six times
1248
most
of patients
greater
than
that
for
the
general
Volume
popula-
12
Number
6
tion (3). In addition, an association may exist between appendiceal mucocele and mucinsecreting tumors of the ovary (4). Treatment of benign cystadenoma and mucosal hyperplasia is simple appendectomy. Because predicting the underlying cause merely by inspecting the serosal surface of a dilated appendix may be difficult, some suggest that a frozen section examination should be done while the abdomen is open (5). If a cystadenocarcmnoma is found, a right colectomy is mandatory. Complications include rupture
of the
pseudomyxoma
mucocele, peritonei,
development torsion
with
of
Radiographically, mass,
a mucocele possibly
with
is seen peripheral
cur-
varies,
corresponding
Pizzimbono
CA, et al.
Muco-
AJ, Heinonen R, Lauren P. Benign and malignant mucocele of the appendix. Acta
Aho
3.
Chir Scand 1973; 139:392-400. WolffM, Ahmed N. Epithelial
the vermiform papillary
4.
appendix.
adenoma,
neoplasms
of
II. Cystadenoma,
and
adenomatous
polyps
ofthe appendix. Cancer 1976; 37:25 11-2522. Young RH, Gilks CB, Scully RE. Mucinous tumors of the appendix associated with mucinous tumors of the ovary and pseudomyxoma peritonei. AmJ Surg Pathol 1991; 15:4 15429.
5.
Pagnozzi
JA, Mueller
sal hyperplasia
appendix:
SC, Cioroiu
(mucocele)
report
M.
of the
of a case.
Muco-
vermiform
Dis Colon
Rectum
1988; 3 1:735-737.
6.
Woodruff lignant
to the
ceration. CT appearance also varies. The contents of the cystic mass, with or without wall calcification or septations, range from near-water attenuation to soft-tissue attenuation, depending on the presence of mucin or debris within the mucocele (12). Pseudomyxoma peritonei
1992
E, RosaiJ,
2.
(8). US appearance
Higa
sal hyperplasia, mucinous cystadenoma, and mucinous cystadenocarcmnoma of the appendix: a re-evaluation of appendiceal mucocele. Cancer 1973; 32:1525-1541.
as a
contents of the mucocele, which may be thin and watery or thick and gelatinous. Patterns include a purely cystic lesion with anechoic fluid, a hypoechoic mass containing fine internal echoes, and a complex mass with highlevel echoes (9,10). Gravity-dependent echoes represent layering of protein macroaggregates or mnspissated mucoid material (10). A typical pattern ofvertical linear echoes, described as a “vortical fold,” can simulate mntussusception, although this rarely complicates mucoceles. Calcification of the wall is difficult to recognize with US (1 1). Polypoid excrescence may be seen projecting mntraluminally from the wall, probably representing proliferation of hyperplastic epithelium. Internal, thin septations have been seen with US, as well as variable degrees of mucosal atrophy and ul-
November
REFERENCES
gan-
vilinear calcification. A barium enema examination classically demonstrates nonfilling of the appendix and an extrinsic or submucosal mass at the cecal tip with intact overlying mucosa
U 1.
grene and hemorrhage, and herniation into the cecum causing varying degrees of bowel obstruction. Of these, pseudomyxoma peritonei is the most likely (6). Preoperative diagnosis of mucocele is helpful to the surgeon in that careful mobilization may reduce the possibility of rupture, peritoneal contamination, and development of pseudomyxoma peritonei (7). Pseudomyxoma peritonei results in a severe inflammatory response and ascites and is associated with malignant mucoceles. soft-tissue
may also be demonstrated, with fibrotic reaction adjacent to the mucocele and ascites and with associated scalloping of the margins of the liver and other organs (13). Gallium scintigraphy may demonstrate intense early uptake, despite the lack of inflammatory cells, possibly due to the acid mucopolysaccharide component of the mucus, which has an affinity to the analogue ferric iron (14).
7.
R, McDonald cystic
JR.
Benign
and
tumors
of the appendix. 1940; 7 1:750-755.
Gynecol Obstet Koster LH. Symptomatic mucocele appendix diagnosed preoperatively. Surg
1974;
ma-
Surg
of the Am J
127:582-584.
8.
Euphrat EJ. Roentgen features of mucocele of the appendix. Radiology 1947; 48:113-
9.
Sandler trasonic
117.
MA, PearlbergJL, and
of mucocele Med 1984;
Madrazo
BL.
UI-
computed tomographic features of the appendix. J Ultrasound 3:97-99.
10.
Parulekar
1 1.
diseases of the appendix. J Ultrasound Med 1983; 2:59-64. Shaane P, Ruud TE, HaffnerJ. Ulti-asonographic features of mucocele of the appendix. JCU 1988; 16:584-587.
12.
Callen tion
5G.
PW.
Ultrasonographic
Computed
of abdominal
tomographic
and
13.
ology 1979; 131:171-175. Madwed D, Mindeizun cocele of the appendix:
14.
Seshul
1992;
finding
pelvic
in
evalua-
abscesses.
R, Jeffrey RBJr. image findings.
Radi-
MuAJR
159:69-72.
MB, Coulam
CM.
Pseudomyxoma
peritonei: computed tomography raphy. AJR 1981; 136:803-806.
Macek
et 31
U
and
RadioGraphics
sonog-
U
1249
