AJR 2004; 183:1316-1318
© American Roentgen Ray Society
Clostridium septicum Infrarenal Aortitis Secondary to Occult Cecal Adenocarcinoma
Creed M. Rucker1,
Christine O. Menias1,
Sanjeev Bhalla1,
Patrick Geraghty2 and
Jay P. Heiken1
1 Mallinckrodt Institute of Radiology, Washington University School of Medicine,
510 S Kingshighway, St. Louis, MO 63110.
2 Department of Vascular Surgery, Washington University School of Medicine, 660
S Euclid, St. Louis, MO 63110.
Received November 6, 2003;
accepted after revision May 6, 2004.
Address correspondence to C. O. Menias.
Introduction
Ahigh number of necrotizing clostridial infections, Clostridium
septicum in particular, are associated with gastrointestinal and
hematologic malignancy [1].
This relationship is sufficiently striking to warrant a thorough investigation
for occult neoplasm if tissue or blood cultures reveal the presence of C.
septicum. Spontaneous clostridial infections—that is, those
unrelated to antecedent trauma or surgery—usually manifest as gas
gangrene, atraumatic myonecrosis, or fulminant sepsis
[2]. We report two cases of
infrarenal C. septicum aortitis associated with adenocarcinoma of the
colon. To our knowledge, these cases comprise only the 10th and 11th cases of
C. septicum aortitis reported in the English-language literature.
Case Reports
A 77-year-old woman was transferred to our institution for abdominal pain,
fever, and leukocytosis. The patient complained of approximately 2 weeks of
vague progressive abdominal pain accompanied by fever, chills, nausea, and
anorexia. Medical history was significant for chronic renal insufficiency due
to polycystic kidney disease and hypertension. There was no history of
abdominal surgery. At presentation, the patient was afebrile and other vital
signs were within normal limits. Physical examination revealed a soft,
diffusely tender abdomen without peritoneal signs. Laboratory values were
remarkable for a WBC of 23.0 x 103/µL with 92%
neutrophils, blood urea nitrogen of 36 mg/dL, creatinine of 1.9 mg/dL, and
hemoglobin of 12 g/dL.
In light of the patient's history of chronic renal insufficiency, a CT
examination of the abdomen and pelvis was performed after the administration
of oral but not IV contrast material. Transaxial images and multiplanar
reconstructions revealed a large amount of concentric intramural gas within an
abdominal aortic aneurysm that measured 4.0 cm in diameter
(Fig. 1A). Retroperitoneal air
extended caudad from the level of the infrarenal aorta along the iliac
vessels. Several pockets of gas were also identified along both psoas margins.
The retroperitoneal fat surrounding the abdominal aorta was diffusely
increased in attenuation. In addition, an ill-defined inflammatory process was
noted in the right lower quadrant, characterized by thickening of the cecal
tip, pericecal fluid, and mesenteric fat infiltration (Figs.
1B and
1C). In keeping with the
history of polycystic kidney disease, both kidneys were markedly enlarged and
replaced by innumerable cysts, some of which were hyperattenuating, which is
consistent with hemorrhage.
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Fig. 1A. —77-year-old woman transferred to our institution with
abdominal pain, fever, and leukocytosis. Unenhanced axial CT image shows
massively enlarged kidneys nearly replaced by innumerable mixed-density cysts,
consistent with known history of adult polycystic kidney disease. Numerous
pockets of gas are visible within intimal layer of infrarenal aortic aneurysm
and retroperitoneum. Infiltration of surrounding retroperitoneal fat due to
inflammation is also present. Arrows = gas in aortic wall.
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Fig. 1B. —77-year-old woman transferred to our institution with
abdominal pain, fever, and leukocytosis. Coronal reconstructions show
ill-defined mass in region of cecum that corresponds to cecal adenocarcinoma.
Cecal tip is thickened, and small amount of pericecal fluid can be seen. In
anterior right lower quadrant, possible site of perforation with extension of
mass into abdominal wall (arrow, B) is seen. Arrows in
C = gas surrounding perforated colon cancer.
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Fig. 1C. —77-year-old woman transferred to our institution with
abdominal pain, fever, and leukocytosis. Coronal reconstructions show
ill-defined mass in region of cecum that corresponds to cecal adenocarcinoma.
Cecal tip is thickened, and small amount of pericecal fluid can be seen. In
anterior right lower quadrant, possible site of perforation with extension of
mass into abdominal wall (arrow, B) is seen. Arrows in
C = gas surrounding perforated colon cancer.
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On the basis of these findings, the patient was taken emergently to the
operating room. In anticipation of performing aortic resection, extraanatomic
revascularization was first performed by placing a right axillobifemoral
bypass graft. After the axillary and femoral incisions were closed, the
abdomen was entered. The infrarenal abdominal aortic aneurysm was found to
contain extensive necrosis. Exploration of the right lower quadrant revealed a
necrotic mass that replaced most of the ileocecal valve, traversed the cecum,
and invaded the adjacent anterior abdominal wall. The colorectal surgery team
performed a right hemicolectomy with abdominal wall resection to remove the
cecal tumor. The vascular surgery team resected the infrarenal aortic aneurysm
and bilateral common iliac arteries and widely débrided the surrounding
infected retroperitoneum.
Examination of the surgical specimens revealed the cecal mass to be a
poorly differentiated adenocarcinoma with mucinous features that extended
directly into the adjacent abdominal wall. The resected abdominal aorta showed
acute and chronic inflammation with necrosis and abscess formation. Cultures
of the aortic tissue grew abundant C. septicum.
The patient's postoperative course was complicated by multiorgan failure
due to fulminant sepsis. Second-look laparotomy with aggressive abdominal
lavage was performed, but the patient's status continued to decline. The
patient's family refused further aggressive management in accordance with the
patient's living will. Comfort measures were provided, and the patient died on
the 42nd postoperative day.
Approximately 10 months later, a 91-year-old woman presented to our
emergency department with abdominal pain and neutrophilia. Contrast-enhanced
CT examination of the abdomen and pelvis showed air tracking along the intimal
layer of the normal-caliber aorta from the level of the superior mesenteric
artery to the iliac bifurcation (Figs.
2A and
2B). Periaortic inflammatory
stranding and small periaortic lymph nodes were also present. In addition, a
large soft-tissue mass was identified in the proximal transverse colon (Figs.
2B and
2C). On the basis of these
imaging findings, a unifying diagnosis of primary colon carcinoma with
secondary aortitis caused by a gas-forming organism, likely a clostridial
species, was made. The diagnosis was verified when the patient became
bacteremic and subsequent blood cultures grew C. septicum. The
pathologic specimen from right hemicolectomy confirmed moderately
differentiated colon adenocarcinoma.
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Fig. 2A. —91-year-old woman with diffuse abdominal pain and
neutrophilia. Contrast-enhanced CT image shows gas dissecting along intimal
layer of abdominal aorta from level of superior mesenteric artery to iliac
bifurcation. Marked periaortic inflammatory stranding is present. Aorta is
atherosclerotic and contains mural thrombus but is normal in caliber. Arrow =
gas in aortic wall.
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Fig. 2B. —91-year-old woman with diffuse abdominal pain and
neutrophilia. Contrast-enhanced CT images obtained near iliac bifurcation show
large soft-tissue mass (arrows) characterized by marked mural
thickening of proximal transverse colon. No evidence of bowel obstruction is
present. Gas tracking along course of common iliac arteries is again
noted.
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Fig. 2C. —91-year-old woman with diffuse abdominal pain and
neutrophilia. Contrast-enhanced CT images obtained near iliac bifurcation show
large soft-tissue mass (arrows) characterized by marked mural
thickening of proximal transverse colon. No evidence of bowel obstruction is
present. Gas tracking along course of common iliac arteries is again
noted.
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Discussion
Periaortic air is an ominous radiologic finding that constitutes a surgical
emergency. The causes of periaortic air include aortoenteric fistula; mycotic
aneurysm; postoperative graft infection; or, as in our patients, seeding of
the aorta secondary to an infectious intraabdominal process, such as
perforated appendicitis or colon carcinoma. The radiologist should always seek
an underlying cause for this finding because primary aortitis is exceedingly
rare. Furthermore, such information may prompt the vascular surgeon to combine
skills with another surgical subspecialty in the operating room to address all
intraabdominal processes as part of a large effort.
Although C. septicum comprises only 1.3% of all clostridial
infections [1], it is a
clinically important organism because of its reported association with
malignancy, first documented by Alpern and Dowell in 1969
[2]. If cultures of infected
blood or tissue grow C. septicum, a search for occult neoplasm is
warranted because up to 85% of such infections have been found to coexist with
underlying malignancy [2].
According to one series, approximately 36% of C. septicum infections
occurred in patients with unsuspected cancer
[3]. The malignancies most
highly associated with C. septicum are of gastrointestinal and
hematologic origin. In the study by Kornbluth et al.
[3] of patients with C.
septicum infection found to have occult cancer, 84% had adenocarcinoma of
the colon and the cecum was reported to be the most common site. Of those with
a known underlying malignancy, 34% had colon carcinoma and 40% had hematologic
malignancy [3].
Why clostridial infections occur in patients with malignancy is not
certain. C. septicum is a gram-positive, spore-forming, gas-producing
anaerobe. It is not thought to be part of the normal flora of the human
gastrointestinal tract, although it has been found in 10-63% of normal
appendices, which may explain the reported high association with cecal cancer
in particular [4]. This theory,
however, has not been supported by recent studies. The bowel mucosa when
compromised, as found in patients with perforated colon cancers or colitis due
to leukemia, neutropenia, or chemotherapy, may provide a portal of entry for
bacterial seeding of the blood by this organism and thus lead to distant
infection [5]. Alternatively,
the low pH and reduced oxidation-reduction potential in necrotic tumors may
provide the appropriate environment for clostridia to thrive because this
bacterium is known to proliferate in devitalized tissues
[6]. C. septicum is
relatively more aerotolerant than the other clostridia species and thus a
hardier organism, which may explain its higher association with malignancy
[7].
Aortic infection by the C. septicum organism is exceedingly rare.
Staphylococci, streptococci, and salmonellae are more common pathogens to
affect atherosclerotic vessels
[8]. Atraumatic clostridial
infections usually manifest as gas gangrene, spontaneous myonecrosis, or
fulminant sepsis. Our first case is rare in that the patient's C.
septicum infection resulted in seeding of an infrarenal abdominal aortic
aneurysm, which progressed to necrotizing aortitis
[9]. Presumably, the
atherosclerotic changes in the aneurysm predisposed it to germination by
C. septicum.
In conclusion, in patients with no known history of cancer, the presence of
clostridial species, particularly C. septicum, in infected blood or
tissue is a strong indicator of associated malignancy and thus warrants a
thorough evaluation for occult neoplasm, especially adenocarcinoma of the
colon.
References
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Introduction
Case Reports
