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961
Colonic
Inverted Air Contrast
Diverticulum:
Barium
Enema
Findings
in
Six Cases
Seth
N. GIick1
A polypoid elevation of the colonic wall was identified on air contrast barium enema in six patients. The abnormality in each case was found to be an inverted colonic diverticulum. Inverted diverticula appeared as broad-based, smooth, sessile polyps measuring 1.5-2.0 cm. In five of the six patients a characteristic and/or evidence of barium within the polyp could be identified.
central umbilication The diagnosis was
confirmed in three patients by demonstrating an everted diverticulum replacing the suspected lesion. In the remaining three patients, two of whom had normal findings on colonoscopy, the diagnosis was strongly suggested by the presence of barium extending into the substance
of the mass.
Additional radiologic maneuvers or a second study may permit accurate diagnosis if the possibility of inverted diverticulum is considered. However, even when the diverticulum cannot
be demonstrated,
a central
umbilication
or barium
minal projection should suggest inverted diverticulum copy or inadvertent diverticulectomy. AJR
156:961-964,
a smooth
intralu-
and prevent unnecessary
within
endos-
May 1991
The distinction between colonic diverticula and polyps on air contrast examination is usually readily apparent. On rare occasions, a diverticulum may be responsible for an intraluminal projection on barium enema, resulting in diagnostic confusion. One cause of such an abnormality is an inverted diverticulum. The head of the diverticulum may prolapse into the lumen of the diverticulum and extend into the lumen of the colon. Alternatively, the base of the diverticulum may invaginate into the lumen, acting as the lead point of minimal intussusception. This phenomenon may also be observed at endoscopy, and in two cases inadvertent diverticulectomy has been performed [1 2]. Only two previous examples of inverted colonic diverticulum have been described in the radiologic literature [3, 4]. However, their occurrence may be more frequent than is currently recognized. Six patients with an inverted diverticulum were identified in a 1 -year period. Radiologic features that should permit a specific diagnosis or suggest this diagnostic possibility were identified in these cases. Unnecessary colonoscopy or even inadvertent diverticulectomy can be avoided. ,
Materials
Received October 15, 1990; accepted vision November 29, 1990. Department of Diagnostic Radiology,
after reHahne-
University Hospital, Broad and Vine Sts., Philadelphia, PA 19102. Address reprint requests to S. N. Glick. mann
0361 -803X/91/1
565-0961
© American Roentgen Ray Society
and Methods
During a 1 -year period, six patients, all of whom intraluminal elevations on air contrast barium enema
represent
inverted
mass
or without
with
colonic ulceration,
diverticula. and
had occult blood in the stools, had that were subsequently confirmed to
In four cases the abnormality simulated a mucosal two cases a mural lesion was suggested.
in the remaining
No other lesions were identified in any of the patients. However, multiple diverticula were present in all of the patients. The patients were four women and two men ranging in age from 65 to 72 years, except for one 27-year-old man. Colonoscopy was performed in three, and no colonic disease was identified in any of these patients. The presence of diverticula was not mentioned in any of the reports.
962
GLICK
AJR:156,
Fig. 1.-A,
Smooth,
broad-based
May 1991
intraluminal
projection (curved arrow) on lateral wall of distal ascending colon shows a central collection of barium (short arrow) suggesting ulceration. B, Increasing distension with air causes par-
tial obliteration
Downloaded from www.ajronline.org by 178.131.56.249 on 11/14/15 from IP address 178.131.56.249. Copyright ARRS. For personal use only; all rights reserved
lum (arrow)
of lesion, and a small diverticu-
is noted
within
center
of defect
Fig. 2.-A, A 2-cm, flat, sessile polyp (large arrow) is shown on lateral wall of mid ascending colon. Lobulated contour suggests a mucosal plaque. Lack of spiculation weighs against diagnosis of diverticulitis. A central umbilication (small arrow) simulating an ulcer and characteristic of inverted diverticulum is noted. B, After additional air insufflation, a faint collection of barium (white arrow) is seen adjacent to polypoid mass (black arrow).
A
B
Results All of the filling defects were between 1 .5 and 2.0 cm in diameter (average, 1 .8 cm). Five of the six were located in the mid to distal ascending colon; four of these were on the lateral wall and one was on the medial wall. The sixth case was on the superior wall of the distal transverse colon. Five of the lesions appeared as smooth-surfaced, broadbased, sessile polyps. Four of these five had central umbilications simulating ulcerations. In the fifth, demonstration of faint barium density within the filling defect initially suggested a calcified lesion, but inverted diverticulum also was considered. In two of the four with central umbilication, inverted diverticulum was suspected. A positive diagnosis was made by further insufflation of air, which produced eversion of the diverticulum in one patient (Figs. 1 A and 1 B) and barium within the body of the polyp in the other (Figs. 2A and 2B). In the patient whose findings initially suggested a calcified polyp, further insufflation resulted in eversion of the diverticulum (Figs. 3A and 3B). A review of the films of two patients who had normal endoscopic findings after a report of polyps on barium enema (both radiologic examinations were performed
early in the series) revealed the characteristic umbilication in a smooth, broad-based defect. The sixth patient had a smooth intraluminal filling defect that appeared on a lateral decubitus radiograph to have a short, thick stalk similar to a lipoma(Figs. 4A and 4B). Findings on colonoscopy were normal, and a second barium enema showed a large diverticulum at the site of the previous polyp (Fig. 4C).
Discussion The diagnostic problems created by diverticula in the detection of polypoid disease of the colon are well known [3, 5, 6]. Several radiologic features that facilitate the discrimination of these lesions have been reported [5]. These criteria are directly or indirectly related to the extraluminal and saccular nature of a diverticulum as opposed to the space-occupying intraluminal polyp. However, on occasion a diverticulum may appear as a polypoid filling defect. Inspissated stool in a diverticulum may produce such a defect, and differentiation may be difficult [7]. If a part of the lesion can be identified as
AJR:156,
INVERTED
May 1991
COLONIC
DIVERTICULUM
963
Fig. 3.-A, A smooth, broad-based elevation is present on superior surface of distal transverse colon (curved arrow). A faint ring-shaped density (open arrow) that suggests calcification
Downloaded from www.ajronline.org by 178.131.56.249 on 11/14/15 from IP address 178.131.56.249. Copyright ARRS. For personal use only; all rights reserved
is identified
within lesion.
B, Further insufflation of air resufted in elimination of abnormality and barium filling diverticulum (arrow).
B
Fig. 4.-A, A 1.8-cm, smooth, broad-based a lucency in barium pool. B, Lateral imperceptibly
decubitus film again with head.
shows
polyp
polyp (arrow)
with slight Iobulation
as a barium-coated
structure
is noted on medial wall of distal ascending
(long
arrow)
with
suggestion
of a short thick stalk (short
C, A barium enema performed 2 days after endoscopic findings were normal shows a large diverticulum (arrow)
projecting beyond the lumen when viewed in tangent, the diagnosis may be suggested. In addition, the ring of barium within the diverticulum surrounding the stool may be nonuniform in thickness when viewed en face owing to incomplete obliteration of the diverticular orifice by the stool. Another polypoid manifestation of a diverticulum is inversion of the diverticulum into the lumen. This phenomenon has been described with Meckel diverticula [4] and appendiceal intussusception [8]. However, information on inverted colonic diverticula is limited. Freeny and Walker [4] reported the first case in the radiologic literature. A 3-cm, smooth cecal mass was present on two separate barium enema studies. Surgery was required for diagnosis. Keller et al. [3] demonstrated a case in which an inverted diverticulum appeared as a small (1 cm), smooth, sessile filling defect that was misinterpreted as a polyp. After endoscopy with normal findings, a second barium enema showed a diverticulum at the site of the pre-
colon. “Lesion”
appears
arrow)
as
merging
at site of polyp.
vious “lesion.” In retrospect, a small wisp of barium could be identified outside the lumen. References to this entity in the endoscopic literature are equally uncommon. Shah and Mazza [9] reported a 1 -cm, sessile sigmoid polyp whose surface color was similar to that of the adjacent normal mucosa. The lesion was soft and easily indented. Dimpling during probing at the site of invagination was described; unlike the similarly soft lipoma, radiating folds also were visible at the site of indentation. They concluded that this represented an inverted diverticulum. Schuman [2] reported the endoscopic removal of a “submucosal” sigmoid polyp, which on pathologic examination proved to be a diverticulum. Although the patient was not treated, no complications occurred as a result of the diverticulectomy. Ladas et al. [1] performed a polypectomy on a 2-cm pedunculated sigmoid polyp that had a thick stalk and a red surface similar to the adjacent mucosa. The pathologic specimen indicated
GLICK
Downloaded from www.ajronline.org by 178.131.56.249 on 11/14/15 from IP address 178.131.56.249. Copyright ARRS. For personal use only; all rights reserved
964
that
the polyp
with
bowel rest and antibiotics,
was
a diverticulum.
The
patient
and no evidence
was
treated
was found
of free intraperitoneal air or clinical complications. In this study, six cases of inverted diverticulum were identified in a 1 -year period. All of the cases were proved or strongly suggested by the radiologic observations. None of the cases had pathologic confirmation, because no polypoid lesions were identified at colonoscopy and no patient required surgery to verify a persistent lesion. Inverted diverticula were characterized by a 1 .5- to 2.0-cm,
broad-based,
smooth
elevation
with
a central
umbilication
and/or evidence of barium beyond the confines of the mucosa. The size of the filling defect may be disproportionate to the size of the diverticulum because invagination of the adjacent wall may contribute to the defect. One case had a short thick stalk that merged imperceptibly with the head, suggesting a lipoma. When an abnormality with this appearance is identified in the presence of other diverticula, the possibility of inverted diverticulum should be considered. Three of the cases were initially misdiagnosed as polyps. However, after a review of the films revealed the distinctive features, the remaining three
cases were recognized
and confirmed.
Additional
insufflation
of air resulted in eversion of the diverticulum or evidence of barium in the lesion. Interestingly, all of the cases were proximal to the splenic flexure, with five located in the ascending colon. This is in contrast to the more frequent location of diverticula in the sigmoid colon. This may be related to segmental variations in mural structure, motility patterns, and intraluminal pressures. However, the numbers are too small to derive any conclusions.
AJR:156, May 1991
Recognition of inverted colonic diverticulum on barium enema may prevent unnecessary endoscopy. Even when this diagnosis cannot be confirmed, radiologic features may suggest this possibility and alert the endoscopist, thereby preventing diverticulectomy. Although no complications have been reported from this procedure, the potential for bleeding or perforation remains. Finally, awareness of the entity may be useful in resolving radiologic-endoscopic discrepancies. Careful review of the barium enema or, when necessary, a second study may permit accurate diagnosis and result in appropriate management. REFERENCES 1 . Ladas SD, Prigouris SP. Pantelidaki C, Raptis SA. Endoscopic removal of inverted sigmoid diverticulum-is it a dangerous procedure? Endoscopy 1989;21 :243-244 2. Schuman BM. Endoscopic diverticulectomy in the sigmoid colon. Gastrointest Endosc 1982;28:189-190 3. Keller CE, Halpert RD. Feczko PJ, Simms SM. Radiologic recognition of colonic diverticula simulating polyps. AJR 1984;143:93-97
4. Freeny PC, Walker JH. Inverted diverticula
of the gastrointestinal
Gastrointest Radiol 1979;4 :57-59 5. Htoo AM, Bartram Cl. The radiological diagnosis of polyps of diverticular disease. Br J Radiol 1979;52:263-267
tract.
in the presence
6. Baker SR, Alterman DD. False-negative barium enema in patients with sigmoid cancer and coexistent diverticula. Gastrointest Radiol 1985; 10:171-173
7. Ott DJ, Kerr RM, Gelfand DW. Colonic diverticula with stool simulating polyps. Gastrointest Endosc 1987:33:252-254 8. Berk RN, Lasser EC. Radiology of the ileocecal area. Philadelphia: Saunders, 1975:162-171 9. Shah AN, Mazza BR. The detection of an inverted diverticulum by colonoscopy. Gastrointest Endosc 1982;28: 188-1 89
961
Colonic
Inverted Air Contrast
Diverticulum:
Barium
Enema
Findings
in
Six Cases
Seth
N. GIick1
A polypoid elevation of the colonic wall was identified on air contrast barium enema in six patients. The abnormality in each case was found to be an inverted colonic diverticulum. Inverted diverticula appeared as broad-based, smooth, sessile polyps measuring 1.5-2.0 cm. In five of the six patients a characteristic and/or evidence of barium within the polyp could be identified.
central umbilication The diagnosis was
confirmed in three patients by demonstrating an everted diverticulum replacing the suspected lesion. In the remaining three patients, two of whom had normal findings on colonoscopy, the diagnosis was strongly suggested by the presence of barium extending into the substance
of the mass.
Additional radiologic maneuvers or a second study may permit accurate diagnosis if the possibility of inverted diverticulum is considered. However, even when the diverticulum cannot
be demonstrated,
a central
umbilication
or barium
minal projection should suggest inverted diverticulum copy or inadvertent diverticulectomy. AJR
156:961-964,
a smooth
intralu-
and prevent unnecessary
within
endos-
May 1991
The distinction between colonic diverticula and polyps on air contrast examination is usually readily apparent. On rare occasions, a diverticulum may be responsible for an intraluminal projection on barium enema, resulting in diagnostic confusion. One cause of such an abnormality is an inverted diverticulum. The head of the diverticulum may prolapse into the lumen of the diverticulum and extend into the lumen of the colon. Alternatively, the base of the diverticulum may invaginate into the lumen, acting as the lead point of minimal intussusception. This phenomenon may also be observed at endoscopy, and in two cases inadvertent diverticulectomy has been performed [1 2]. Only two previous examples of inverted colonic diverticulum have been described in the radiologic literature [3, 4]. However, their occurrence may be more frequent than is currently recognized. Six patients with an inverted diverticulum were identified in a 1 -year period. Radiologic features that should permit a specific diagnosis or suggest this diagnostic possibility were identified in these cases. Unnecessary colonoscopy or even inadvertent diverticulectomy can be avoided. ,
Materials
Received October 15, 1990; accepted vision November 29, 1990. Department of Diagnostic Radiology,
after reHahne-
University Hospital, Broad and Vine Sts., Philadelphia, PA 19102. Address reprint requests to S. N. Glick. mann
0361 -803X/91/1
565-0961
© American Roentgen Ray Society
and Methods
During a 1 -year period, six patients, all of whom intraluminal elevations on air contrast barium enema
represent
inverted
mass
or without
with
colonic ulceration,
diverticula. and
had occult blood in the stools, had that were subsequently confirmed to
In four cases the abnormality simulated a mucosal two cases a mural lesion was suggested.
in the remaining
No other lesions were identified in any of the patients. However, multiple diverticula were present in all of the patients. The patients were four women and two men ranging in age from 65 to 72 years, except for one 27-year-old man. Colonoscopy was performed in three, and no colonic disease was identified in any of these patients. The presence of diverticula was not mentioned in any of the reports.
962
GLICK
AJR:156,
Fig. 1.-A,
Smooth,
broad-based
May 1991
intraluminal
projection (curved arrow) on lateral wall of distal ascending colon shows a central collection of barium (short arrow) suggesting ulceration. B, Increasing distension with air causes par-
tial obliteration
Downloaded from www.ajronline.org by 178.131.56.249 on 11/14/15 from IP address 178.131.56.249. Copyright ARRS. For personal use only; all rights reserved
lum (arrow)
of lesion, and a small diverticu-
is noted
within
center
of defect
Fig. 2.-A, A 2-cm, flat, sessile polyp (large arrow) is shown on lateral wall of mid ascending colon. Lobulated contour suggests a mucosal plaque. Lack of spiculation weighs against diagnosis of diverticulitis. A central umbilication (small arrow) simulating an ulcer and characteristic of inverted diverticulum is noted. B, After additional air insufflation, a faint collection of barium (white arrow) is seen adjacent to polypoid mass (black arrow).
A
B
Results All of the filling defects were between 1 .5 and 2.0 cm in diameter (average, 1 .8 cm). Five of the six were located in the mid to distal ascending colon; four of these were on the lateral wall and one was on the medial wall. The sixth case was on the superior wall of the distal transverse colon. Five of the lesions appeared as smooth-surfaced, broadbased, sessile polyps. Four of these five had central umbilications simulating ulcerations. In the fifth, demonstration of faint barium density within the filling defect initially suggested a calcified lesion, but inverted diverticulum also was considered. In two of the four with central umbilication, inverted diverticulum was suspected. A positive diagnosis was made by further insufflation of air, which produced eversion of the diverticulum in one patient (Figs. 1 A and 1 B) and barium within the body of the polyp in the other (Figs. 2A and 2B). In the patient whose findings initially suggested a calcified polyp, further insufflation resulted in eversion of the diverticulum (Figs. 3A and 3B). A review of the films of two patients who had normal endoscopic findings after a report of polyps on barium enema (both radiologic examinations were performed
early in the series) revealed the characteristic umbilication in a smooth, broad-based defect. The sixth patient had a smooth intraluminal filling defect that appeared on a lateral decubitus radiograph to have a short, thick stalk similar to a lipoma(Figs. 4A and 4B). Findings on colonoscopy were normal, and a second barium enema showed a large diverticulum at the site of the previous polyp (Fig. 4C).
Discussion The diagnostic problems created by diverticula in the detection of polypoid disease of the colon are well known [3, 5, 6]. Several radiologic features that facilitate the discrimination of these lesions have been reported [5]. These criteria are directly or indirectly related to the extraluminal and saccular nature of a diverticulum as opposed to the space-occupying intraluminal polyp. However, on occasion a diverticulum may appear as a polypoid filling defect. Inspissated stool in a diverticulum may produce such a defect, and differentiation may be difficult [7]. If a part of the lesion can be identified as
AJR:156,
INVERTED
May 1991
COLONIC
DIVERTICULUM
963
Fig. 3.-A, A smooth, broad-based elevation is present on superior surface of distal transverse colon (curved arrow). A faint ring-shaped density (open arrow) that suggests calcification
Downloaded from www.ajronline.org by 178.131.56.249 on 11/14/15 from IP address 178.131.56.249. Copyright ARRS. For personal use only; all rights reserved
is identified
within lesion.
B, Further insufflation of air resufted in elimination of abnormality and barium filling diverticulum (arrow).
B
Fig. 4.-A, A 1.8-cm, smooth, broad-based a lucency in barium pool. B, Lateral imperceptibly
decubitus film again with head.
shows
polyp
polyp (arrow)
with slight Iobulation
as a barium-coated
structure
is noted on medial wall of distal ascending
(long
arrow)
with
suggestion
of a short thick stalk (short
C, A barium enema performed 2 days after endoscopic findings were normal shows a large diverticulum (arrow)
projecting beyond the lumen when viewed in tangent, the diagnosis may be suggested. In addition, the ring of barium within the diverticulum surrounding the stool may be nonuniform in thickness when viewed en face owing to incomplete obliteration of the diverticular orifice by the stool. Another polypoid manifestation of a diverticulum is inversion of the diverticulum into the lumen. This phenomenon has been described with Meckel diverticula [4] and appendiceal intussusception [8]. However, information on inverted colonic diverticula is limited. Freeny and Walker [4] reported the first case in the radiologic literature. A 3-cm, smooth cecal mass was present on two separate barium enema studies. Surgery was required for diagnosis. Keller et al. [3] demonstrated a case in which an inverted diverticulum appeared as a small (1 cm), smooth, sessile filling defect that was misinterpreted as a polyp. After endoscopy with normal findings, a second barium enema showed a diverticulum at the site of the pre-
colon. “Lesion”
appears
arrow)
as
merging
at site of polyp.
vious “lesion.” In retrospect, a small wisp of barium could be identified outside the lumen. References to this entity in the endoscopic literature are equally uncommon. Shah and Mazza [9] reported a 1 -cm, sessile sigmoid polyp whose surface color was similar to that of the adjacent normal mucosa. The lesion was soft and easily indented. Dimpling during probing at the site of invagination was described; unlike the similarly soft lipoma, radiating folds also were visible at the site of indentation. They concluded that this represented an inverted diverticulum. Schuman [2] reported the endoscopic removal of a “submucosal” sigmoid polyp, which on pathologic examination proved to be a diverticulum. Although the patient was not treated, no complications occurred as a result of the diverticulectomy. Ladas et al. [1] performed a polypectomy on a 2-cm pedunculated sigmoid polyp that had a thick stalk and a red surface similar to the adjacent mucosa. The pathologic specimen indicated
GLICK
Downloaded from www.ajronline.org by 178.131.56.249 on 11/14/15 from IP address 178.131.56.249. Copyright ARRS. For personal use only; all rights reserved
964
that
the polyp
with
bowel rest and antibiotics,
was
a diverticulum.
The
patient
and no evidence
was
treated
was found
of free intraperitoneal air or clinical complications. In this study, six cases of inverted diverticulum were identified in a 1 -year period. All of the cases were proved or strongly suggested by the radiologic observations. None of the cases had pathologic confirmation, because no polypoid lesions were identified at colonoscopy and no patient required surgery to verify a persistent lesion. Inverted diverticula were characterized by a 1 .5- to 2.0-cm,
broad-based,
smooth
elevation
with
a central
umbilication
and/or evidence of barium beyond the confines of the mucosa. The size of the filling defect may be disproportionate to the size of the diverticulum because invagination of the adjacent wall may contribute to the defect. One case had a short thick stalk that merged imperceptibly with the head, suggesting a lipoma. When an abnormality with this appearance is identified in the presence of other diverticula, the possibility of inverted diverticulum should be considered. Three of the cases were initially misdiagnosed as polyps. However, after a review of the films revealed the distinctive features, the remaining three
cases were recognized
and confirmed.
Additional
insufflation
of air resulted in eversion of the diverticulum or evidence of barium in the lesion. Interestingly, all of the cases were proximal to the splenic flexure, with five located in the ascending colon. This is in contrast to the more frequent location of diverticula in the sigmoid colon. This may be related to segmental variations in mural structure, motility patterns, and intraluminal pressures. However, the numbers are too small to derive any conclusions.
AJR:156, May 1991
Recognition of inverted colonic diverticulum on barium enema may prevent unnecessary endoscopy. Even when this diagnosis cannot be confirmed, radiologic features may suggest this possibility and alert the endoscopist, thereby preventing diverticulectomy. Although no complications have been reported from this procedure, the potential for bleeding or perforation remains. Finally, awareness of the entity may be useful in resolving radiologic-endoscopic discrepancies. Careful review of the barium enema or, when necessary, a second study may permit accurate diagnosis and result in appropriate management. REFERENCES 1 . Ladas SD, Prigouris SP. Pantelidaki C, Raptis SA. Endoscopic removal of inverted sigmoid diverticulum-is it a dangerous procedure? Endoscopy 1989;21 :243-244 2. Schuman BM. Endoscopic diverticulectomy in the sigmoid colon. Gastrointest Endosc 1982;28:189-190 3. Keller CE, Halpert RD. Feczko PJ, Simms SM. Radiologic recognition of colonic diverticula simulating polyps. AJR 1984;143:93-97
4. Freeny PC, Walker JH. Inverted diverticula
of the gastrointestinal
Gastrointest Radiol 1979;4 :57-59 5. Htoo AM, Bartram Cl. The radiological diagnosis of polyps of diverticular disease. Br J Radiol 1979;52:263-267
tract.
in the presence
6. Baker SR, Alterman DD. False-negative barium enema in patients with sigmoid cancer and coexistent diverticula. Gastrointest Radiol 1985; 10:171-173
7. Ott DJ, Kerr RM, Gelfand DW. Colonic diverticula with stool simulating polyps. Gastrointest Endosc 1987:33:252-254 8. Berk RN, Lasser EC. Radiology of the ileocecal area. Philadelphia: Saunders, 1975:162-171 9. Shah AN, Mazza BR. The detection of an inverted diverticulum by colonoscopy. Gastrointest Endosc 1982;28: 188-1 89
