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ANTICANCER RESEARCH 26: 635-638 (2006)
Mucocele of the Appendiceal Stump due
to Benign Mucinous Cystadenoma
D.P. KORKOLIS1, ∫. APOSTOLAKI2, G.D. PLATANIOTIS1, J. TZORBATZOGLOU1,
I.G. KARAITIANOS1 and P.P. VASSILOPOULOS1
1First
Department of Surgery and 2Department of Surgical Pathology,
Hellenic Anticancer Institute, "St. Savvas" Hospital, Athens, Greece
Abstract. Mucocele of the appendix is a rare lesion,
characterized by distension of the lumen due to accumulation
of mucus material. Correct preoperative diagnosis is seldom
achieved. If left untreated, the mucocele may rupture
producing a potentially fatal peritoneal spread. The type of
surgical treatment is related to the dimensions and histology of
the mucocele. In this paper, the case of a 49-year-old woman,
with a previous appendectomy, suffering from a painful mass
in the right lower quadrant of the abdomen, is reported.
Imaging showed a large, cystic structure at the base of the
cecum. Surgery revealed a 8x5.5 cm calcified tumor, which was
excided together with the appendiceal remnant. Pathological
diagnosis was that of a mucocele arising from the appendiceal
stump due to the development of a benign mucinous
cystadenoma.
Appendiceal mucocele is a well-recognized entity that can
present in a variety of clinical syndromes or can occur as
an incidental surgical finding. It is an unsusal lesion that
is characterized by an appendiceal lumen distended with
mucus. Early diagnosis and prompt surgical intervention
are mandatory to prevent spillage of the mucinous
material into the peritoneal cavity causing pseudomyxoma
peritonei (1, 2).
Although well described for the native appendix,
mucocele arising from the appendiceal stump is an
extremely rare oncological entity with only two cases ever
reported in the literature (3, 4). The case of a mucocele
associated with a benign mucinous cystadenoma of the
appendiceal stump is reported.
Correspondence to: Dimitris P. Korkolis, MD, 22 Socratous Street,
1st Floor, 14561 Kifissia, Athens, Greece. Tel: +30 210 8083743,
Fax: +30 210 8012689
Key Words: Mucocele, appendiceal neoplasm, mucinous cystadenoma.
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Case Report
A 49-year-old Caucasian female presented with a 6-month
history of vague right lower quadrant pain radiating through
to the back. The patient had undergone an appendectomy
25 years previously. Total abdominal hysterectomy with
bilateral salpingo-oophorectomy for bleeding myomatous
disease of the uterus had been also performed 5 years
earlier, in our institution.
The patient described no fever, malaise, nausea or
vomiting, change in bowel habits, rectal bleeding or weight
loss. Physical examination of the abdomen revealed slight
tenderness in the vicinity of the old appendectomy surgical
scar. Laboratory analysis, including serum levels of CEA
and CA-125, were found to be within normal limits.
Colonoscopy showed no pathological findings. An
abdominal CT scan demonstrated a well-defined, elliptical,
7x5 cm cystic mass, lying at the inferior aspect of the cecum,
just above the iliac fossa. The lesion had smooth walls,
scattered mural calcifications and no surrounding
inflammation (Figure 1).
The patient underwent exploratory laparotomy through
a midline incision. A firm, well-encapsulated and calcified
tumor, 8x5.5x4 cm in size, was discovered at the base of
the cecum. It was easily mobilized from adjacent
structures and found to originate from the 1-cm,
unburied, appendiceal stump. The lesion was removed
intact, together with the appendiceal remnant and a safe
rim of the cecal wall (Figure 2). Frozen section
examination of the lesion and the margin of resection
were both negative for malignancy.
The resected mucocele contained about 75 ml of mucin.
Histopathological evaluation revealed crowded, irregular,
villotubular structures, with mild to moderate epithelial
atypia together with acellular mucin pooling. No evidence
of malignancy was found (Figure 3). The final diagnosis
ascertained the presence of an appendiceal stump mucocele
associated with a benign mucinous cystadenoma.
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ANTICANCER RESEARCH 26: 635-638 (2006)
Figure 1. Enhanced CT scan shows a well-defined cystic mass at the base of the cecum with smooth walls, scattered microcalcifications and no
surrounding inflammation.
The patient had an uneventful recovery and was
discharged home on the fifth postoperative day. Eighteen
months after surgery, she is free of symptoms with no
evidence of recurrence.
Discussion
Although widely used, the term mucocele is inherently
imprecise and inclusive of both benign and malignant
lesions. Mucoceles are found in only 0.07% to 0.3% of
appendectomies and are histologically subdivided on the
basis of the World Health Organization classification (5, 6).
Specifically, simple mucocele is appendiceal dilation with
accumulation of mucus due to obstruction of the lumen.
Mucinous cystadenoma is defined as the dilated, mucusfilled appendix containing hyperplastic adenomatous
mucosa, and cystadenocarcinoma as the presence of
adenocarcinoma associated with a dilated, mucus-filled
appendix. The last two types comprise the majority of cases.
Yeong et al. (3) reported, for the first time, a unique case of
a mucocele of the appendiceal stump related to a papillary
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cystadenocarcinoma arising at the base and causing
pseudomyxoma peritonei. More recently, Lien et al. (4)
described a mucinous cystadenoma of the appendiceal stump
as the cause of a mucocele developed 30 years after
appendectomy. Our report, in which a specimen was available,
represents the second ever described case of an appendiceal
stump mucocele associated with a benign condition.
Clinical manifestations of appendiceal mucoceles are
non-specific, thus diminishing the rate of accurate
preoperative diagnosis. These include abdominal pain,
palpable mass, weight loss, nausea and vomiting, change in
bowel habits, appendicitis or lower gastrointestinal bleeding
(7). One-quarter of mucoceles are asymptomatic. However,
when symptoms are present a cystadenocarcinoma is more
likely to be encountered. In general, only one-third of them
are malignant, whereas the risk of malignancy increases with
size (8). These data may be influenced by the fact that
routine incidental appendectomy is generally performed
during gynecological or other surgical procedures,
increasing the rate of incidental benign appendiceal
mucoceles, as they would not be detected otherwise. In
Korkolis et al: Mucocele of Appendiceal Stump
Figure 2. The resected specimen included an intact, firm, well-encapsulated and calcified tumor, measuring 8x5.5x4cm.
Figure 3. Microscopic evaluation revealed crowded, irregular, villotubular structures, with mild epithelial atypia and acellular mucin pooling, suggesting
the presence of a benign mucinous cystadenoma.
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ANTICANCER RESEARCH 26: 635-638 (2006)
addition, there might be a referral bias in favor of tertiary
referral centers for symptomatic patients with a large
abdominal mass, rectal bleeding and weight loss, who are
more likely to harbor an appendiceal cystadenocarcinoma.
Of note is the elevated incidence of associated neoplasms
which occur in almost one-third of cases. These include
neoplasms of the colon and rectum and, less frequently,
ovarian, endometrial, bladder, prostate or other
gastrointestinal tract tumors (9). It would, therefore, seem
prudent to recommend surveillance colonoscopy in, at least,
those patients with an established diagnosis of an
appendiceal mucinous cystadenoma.
The initial diagnostic modalities include ultrasound,
barium enema, colonoscopy and CT scan. The latter has
been invaluable in the diagnosis of appendiceal mucocele.
It usually reveals a low-attenuation, well-encapsulating,
cystic mass with smooth walls located at the base of the
cecum, sometimes having mural calcifications (10).
All mucoceles should probably be removed in order to
eliminate the chance of progression to malignancy.
Although an open approach is usually recommended,
laparoscopic appendectomy for mucocele removal has
been described. Caution is advisable because of the risk of
port-site recurrences, as well as accidental intraoperative
rupture, which increases the likelihood of peritoneal
spread (11, 12).
At the time of surgery, a spontaneous appendiceal
perforation or any mucus extravasation from the
appendiceal lumen is strongly suggestive of an underlying
malignancy and should prompt an oncologically-performed
right hemicolectomy. If the lesion is confined to the
appendix, has no surrounding infiltration and is followed by
negative frozen-section examination and clear margins of
resection, wide local resection is usually adequate (2, 13).
Conclusion
Mucocele of the appendiceal stump is an extremely rare
oncological entity. It should, however be, included in the
differential diagnosis of a cystic mass detected in the area
of a previous appendectomy, necessitating thorough
investigation and prompt surgical intervention.
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Received October 18, 2005
Accepted November 25, 2005