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Intussusception in adults: CT diagnosis
Clinical Radiology (1998) 53, 53-57
Intussusception in Adults: CT Diagnosis G. GAYER, S. APTER, C. HOFMANN, S. NASS, M. AMITAI, R. ZISSIN* and M. HERTZ
Departments of Diagnostic Imaging, The Chaim Sheba Medical Center, Tel Hashomer and *Sapir Medical Centre, Kfar Saba, Affiliated to the Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel Purpose: Intussusception in adults is nowadays usually diagnosed on computed tomogr a p h y (CT), as CT is often the first modality for the investigation of prolonged abdominal pain f r o m which these patients suffer. We wish to present the CT, clinical and pathological findings of 16 adult patients with intussusception seen over a 5-year period. Materials and Methods: The abdominal scans of 16 patients with intussusception were reviewed. Special attention was directed to the location of the mass, its shape and fat content, possible underlying pathology and dilatation of the bowel proximally. The findings were correlated with clinical and pathological data. Results: Eight men and eight women, aged 34-81 years, were studied. The most frequent indication for CT was prolonged abdominal pain. CT findings included an inhomogeneous soft tissue mass, target or sausage-shaped, depending on the angle of the CT beam vs. the intussusception, with a fatty component in 14 of the 16. Intussusception was enteroenteric (six), ileocolic (three), or colocolic (seven). Complete small bowel obstruction was present only in one case and some bowel dilatation in three. The underlying pathology could be diagnosed on CT in only two cases of lipoma. Nine patients had an underlying malignant process, eight of them unsuspected. Of the other five, two had coeliac disease, two were classified as idiopathic and one had a necrotic polyp of undetermined pathology. Conclusion: Intussusception on CT presented a characteristic mass lesion containing fat stripes in almost all patients. Obstruction was rarely seen. Malignant lesions were the most common cause and therefore early diagnosis and p r o m p t intervention are essential. Gayer, G., Apter, S., Hofmann, C., Nass, S., Amitai, M., Zissin, R. & Hertz, M. (1998). Clinical Radiology 53, 53-57. Intussusception in Adults: CT Diagnosis
Accepted for Publication 8 April 1997
Intussusception is defined as telescoping of one segment of the gastrointestinal tract into an adjacent one. It is a relatively common entity in childhood in which it presents as an acute illness. In adults, it is manifested most often by chronic abdominal pain. The use of CT as the first imaging modality in the evaluation of patients with abdominal complaints has greatly expanded over the last few years. The radiologist is therefore often the first to suggest the diagnosis of intussusception in a patient with chronic abdominal pain referred for CT. We wish to report 16 adult patients with emphasis on the CT findings and corroborated by clinical and pathological data.
M A T E R I A L S AND M E T H O D S The imaging studies and clinical records of 16 patients diagnosed by CT as having intussusception of the small intestine or colon were retrospectively reviewed. CT was the initial examination to suggest the diagnosis in 14 patients, and it was the only study in 10. In two patients CT was performed after an ultrasound examination raised the possible diagnosis of intussusception. In one patient a barium enema preceded CT, but the intussusception was missed as reduction occurred during the exam. Barium enema was performed in two cases after the CT diagnosis. Correspondence to: Dr G. Gayer, Department of Diagnostic Imaging, Sheba Medical Centre, Tel Hashomer 52621, Israel. 9 1998 The Royal College of Radiologists.
An upper gastrointestinal tract study was performed after CT in three cases. Laparotomy was performed in 13 patients and the intussuscepted bowel segment was resected in 12 patients. CT scans were obtained on either the Elscint 2400 Elite or on the Elscint CT Twin with a scanning time of 2.1 s or 1.1 s and 10 mm collimation with scans at 1.0 cm intervals from the diaphragm to the symphysis pubis and additional scans as needed. Oral contrast material, 500 ml of flavoured solution of 4% Telebrix (meglumine-ioxitalamate) was administered 2 h before the examination and an additional 250 ml just before the study. Intravenous contrast material was used routinely, unless contraindicated by clinical history. Air insufflation per rectum was performed in one case. RESULTS Table 1 shows the relevant clinical, radiological and pathological data of the 16 patients (eight male, eight female) with intussusception. Ages ranged from 34 to 81 years (mean age 58 years). The most frequent indication for CT was prolonged abdominal pain (of several weeks' or even months' duration). Other symptoms and signs included weight loss, constipation and an abdominal mass at physical examination. Five patients had relevant clinical histories: two patients had a known malignant disease; one melanoma (case 9) and one metastatic carcinoma of the stomach (case 16). A third patient (case 7) had undergone nephrectomy for a malignant
54
CLINICAL RADIOLOGY
Table 1 - Main clinical radiological and pathological findings in 16 patients with intussusception
Case
Sex
Age Clinical data (years)
1
F
55
2
M
80
3 4
M F
34 66
5
F
40
6
F
79
7 8
F M
70 34
9
M
10
M
Pathology
CT findings Target or sausageshaped
Fat crescent
Rim of contrast material
Air bubbles in periphery
Bowel dilatation
Coeliac disease, abdominal pain Anaemia, colonoscopy: obstructing lesion Coeliac disease Abdominal pain, fever, leukocytosis Abdominal pain prolonged, abdominal mass Prolonged abdominal pain, abdominal mass
+
+
+
+
-
+
+
+
-
_
+
+
-
+
+
+
+
-
+
+
+
+
+
-
_
Cancer of descending colon
Haemorrhagic necrosis in ascending colon Large cell lymphoma in terminal ileum and caecum Cancer of caecum Cancer of ascending colon Malignant melanoma jejunum Lipoma in sigmoid colon
Abdominal pain
+
+
+
-
_
Abdominal pain, vomiting
+
+
-
-
bowel obstruction
70
Malignant melanoma palpable abdominal mass in L L Q
+
+
+
+
-
47
Abdominal pain RLQ
+
+
-
+
-
Necrotic polyp in terminal ileum White plaques on serosal surface of small bowel Lymphoma in jejunum
Small
recurrent intestinal obstruction 11
F
81
Abdominal pain
+
+
+
-
_
12
M
55
+
+
+
-
_
13
M
48
+
+
+
+
-
14
F
74
_
_
+
+
+
15
F
56
Anaemia, melaena, Upper gastrointestinal bleeding Abdominal pain, weight loss Abdominal pain, constipation, weight loss Prolonged abdominal p a i n
+
+
-
_
_
16
M
36
Cancer of stomach, Abdominal p a i n
+
+
+
-
_
tumour 6 years earlier without evidence of metastatic spread. The last two patients had biopsy-proven coeliac disease (cases 1 & 3). None of these patients had undergone previous surgery of the gastrointestinal tract. Laparotomy was performed in 13 patients and a lead point was found on pathological examination in 11. In one patient (case 11) with small bowel intussusception on CT, bowel resection was not performed and in another patient (case 4), a colocolic intussusception was found at surgery and histologically areas of haemorrhagic necrosis in the wall of the ascending colon were seen but no mass lesion. A repeat colonoscopy 5 months later revealed findings consistent with acute colitis. Of the three patients who did not undergo surgery, two (cases 1 & 3) had biopsy-proven coeliac disease; in case 1 a follow-up CT demonstrated resolution of the condition and patient 3 was lost to follow-up and non-obstructing intussusception of the small bowel was attributed to the underlying coeliac disease. The third patient (case 16) had a history of disseminated metastatic carcinoma of the stomach which was presumed to be the cause of the enteroenteric intussusception. Underlying pathological processes causing the intussusception included carcinoma of the colon in four patients, lymphoma in three (one involving the terminal ileum and caecum, one ileum and one jejunum) and one melanoma metastasis in the jejunum. Two had benign lesions, both lipomas, one in the caecum and the other in the signoid. One
Lipoma ascending colon Cancer of transverse colon Lymphoma in ileo-caecal valve Assumed metastases from gastric cancer
patient had a polypoid lesion in which marked necrosis made a final diagnosis as to its benign or malignant nature impossible (case 10). Intussusception was diagnosed on CT in all 16 patients. The most common finding was a thickened segment of bowel with an eccentrically placed crescent-like fatty area, representing the intussusception and the intussuscepted mesentery (14 cases). This appeared either as a round target mass (Fig. 1) (nine cases) or as an oblong sausageshaped mass (Fig. 2) (two cases) and in three cases both configurations, at different levels depending on the angle of the CT beam vs. the intussusception. The second most common finding was a rim-shaped accumulation of contrast material in the periphery of the mass (Fig. 3). This was present in 11 patients and enabled us to make the diagnosis in the two cases in which the typical crescent-like fat stripe was not demonstrated. In one of the five cases in which this sign was absent the small bowel was totally obstructed. In two cases the contrast material had not reached the intussusception and in another two cases despite passage of contrast material beyond the lesion, a 'rim' was not present. Additionally air bubbles in the uppermost part of the intussusception were observed in seven cases. These air bubbles were proven to be intraluminal and not intramural following rectal insufflation in one case (Fig. 4a, b). In two cases a well-marginated, round homogeneous intraluminal mass with a fat density was demonstrated, characteristic of lipoma (Fig. 5a, b). 9 1998
The Royal College of Radiologists, Clinical Radiology, 53, 53-57.
INTUSSUSCEPTION IN ADULTS
Fig. 1 - Case 3. A round mass lesion in the left lower abdomen consisting of thickened bowel walls with eccentric low density mesenteric fat (arrowhead) within it. A small air bubble is present in the upper part of the loop (arrow). Some dilatation of the small bowel is also seen.
55
(a)
(b) Fig. 2 - Case 10. An elongated mass lesion of soft tissue with fatty tissue within it in the right iliac fossa. Thin soft tissue strands within the fat (arrows) represent mesenteric blood vessels within the invaginated mesenteric fat.
Fig. 3 - Case 1. A round target-shaped mass consisting of different densities is seen in the left mid-abdomen. A peripheral rim of contrast material (curved arrow) with an air bubble on top (arrow) represents the space between the opposing bowel walls of the intussusceptum and the intussuscipiens. A 'half moon'-shaped fatty density (arrowhead) is seen in the centre of the lesion adjacent to a round dense area (open arrow) representing the intussuscepted mesentery and bowel, respectively. 9 1998 The Royal College of Radiologists, Clinical Radiology, 53, 53-57,
Fig. 4 - Case 5. (a) A complex mass lesion (long arrows) of soft tissue surrounded by fluid and some eccentric fatty density tissue. At the upper part of the lesion a few air bubbles (short arrow) are noted. (b) Scan following air insufflation per rectum demonstrates a lobulated inhomogeneous mass surrounded by a large amount of air (arrows) within the lumen of the colon at the splenic flexure.
Additional findings on CT were: a small amount of ascites (two cases), liver lesions (two patients, in one this proved on pathology to be involvement by lymphoma which was also the cause of the small bowel intussusception) and multiple lung nodules suspected to be metastases in four cases (two with carcinoma of the colon, one with melanoma, and another one with melanoma but the intussusception was caused by a lipoma). Three patients had some bowel dilatation proximal to the intussusception and one single patient had complete small bowel obstruction at the level of the intussusception. Upper gastrointestinal tract studies performed in three patients demonstrated respectively a complete obstruction (in a case of melanoma), an ileocolic intussusception (in a case of lymphoma) and areas of destroyed mucosa without definite evidence of intussusception (in another case of lymphoma). The intussusceptions were: enteroenteric (six), ileocolic (three) and colocolic (seven). Their aetiologies are summarized in Table 2.
56
CLINICAL RADIOLOGY
DISCUSSION
(a)
(b) Fig. 5 - Case 13. (a) An invaginating bowel loop (curved arrow) is seen entering a soft tissue mass (open arrows) with at its tip a round mass of fatty density surrounded by a thin rim of contrast material (wide arrow). (b) A scan 2 cm more caudally demonstrates clearly a round, well-demarcated lipoma surrounded by contrast material (arrow). Note the soft tissue density (open arrows) adjacent to the lipoma.
Table 2 - Underlying pathology and localization of intussusception in 16 cases
Underlying pathology
Localization Enteroenteric
Total lleocolic Colocolic
Benign Coeliac disease Lipoma
2
Malignant Carcinoma Lymphoma Melanoma metastasis Carcinoma metastasis
1 1 1
Idiopathic Undetermined
1
Total
6
1 1 3
7
2 1 16
Intussusception is rare in adults when compared with children and has a demonstrable cause in 90% of cases [1]. These patients are nowadays most often diagnosed on CT. Benign or malignant tumours account for ~ 65% of the underlying pathology [1]. The CT appearance of intussusception is characteristic and has been confirmed experimentally in animal models and proven clinically [2-7]. The major CT features in our series were similar to those previously described including: (1) An apparent mass lesion, caused by a thickened segment of bowel, the intussusceptum telescoping into the intussuscipiens. (2) A crescent-like, eccentric low attenuation fatty mass, representing entrapped mesenteric fat. The combination of these two features produces a target or sausageshaped mass, depending on the angle of the CT beam vs. the intussusception. (3) A rim of contrast material encircling the intussusceptum, representing coating of the opposing bowel walls of the intussusceptum and intussuscipiens. This feature is analogous to the coil spring sign of intussusception, seen on a barium enema [6]. This sign enabled us to make the diagnosis in the two cases in which mesenteric fat was not visualized within the mass. (4) Air bubbles peripheral to the upper part of the intussusception, which just like contrast material may enter between the opposing bowel walls. The location of these bubbles should not be confused with intramural air which reflects vascular compromised bowel. Intraluminal air tends to accumulate uppermost when the patient is examined in the supine position [3], whereas intramural air can appear anywhere in the periphery of a mass lesion. (5) A leading mass was infrequently seen in our study as only two cases of lipoma were identified with certainty on CT. CT provided confident identification of intussusception in all 16 cases but the exact aefiology could not be determined with certainty except in the cases of lipoma, which presented as well-marginated, round homogeneous masses with a density of fat content, unlike the mesentefic, peripherally placed fat seen in entrapped mesenteric fat. Benign and malignant causes of intussusception could not be distinguished on CT in this and other series [2,6,7-9]. One of our cases with colonic lipoma as a leading mass (case 13) showed a prominent soft tissue mass adjacent to the lipoma. This was also described by Donovan et al. [6]. This soft tissue pseudotumour represents the intussusceptum itself and not the leading mass. The other patient with a lipoma as a lead point (case 9) had been treated for melanoma, but the intussusception was unrelated to the known malignancy. A similar case of a lipoma in a patient with two primary neoplasms was reported by Lorigan et al. [4]. Thus, even in patients with known malignancy, intussusception may be caused by a benign process. In three cases there was some dilatation of the bowel proximal to the intussusception, and in one case a jejunojejunal intussusception caused complete obstruction. In the other 12, the proximal bowel loops were normal. The absence of bowel obstruction may account for the chronicity of the condition. The lack of proximal bowel dilatation in most of our patients is in contrast to a report of nine patients, all of whom showed some proximal bowel dilatation [2]. In a review of 25 adults with intussusception Agha classified them according to their aefiology as: tumourrelated (13 cases), postoperative (nine cases), miscellaneous (one case) and idiopathic (two cases) [1]. 9 1998 The Royal College of Radiologists, ClinicalRadiology, 53, 53-57.
INTUSSUSCEPTION IN ADULTS
In our series too, the majority of patients (12 out of 16) had an underlying tumour (nine malignant, two benign and one necrotic polyp). These were about evenly distributed in the small and large bowel. The incidence of underlying malignancy of the small bowel in intussusception is usually reported to be much less [9,10] than in this small series (five of nine). We encountered no patients with a postoperative intussusception, although this was the experience in nine out of 25 cases reported [1]. We classified two of our cases as idiopathic: in case 11 with an enteroenteric intussusception, no intussusception was found at laparotomy but only white plaques were seen on the serosa, and bowel resection was not performed. The other patient (case 4) underwent fight colectomy and areas of haemorrhagic necrosis in the wall of the colon were observed, but no mass lesion was present. Two patients with enteroenteric intussusception had coeliac disease. There are only a few case reports of intussusception in this disease. Marshak and Lindner stated that intussusception is not uncommon in coeliac disease, but that it is easily missed due to its transient nature [11]. Cohen and Lintott reported six adult coeliac patients with transient nonobstructing intussusception of the small bowel on a barium meal [12]. They stated that it occurs in at least 20% of adults with coeliac disease, and considered it an additional radiological sign in the diagnosis of coeliac disease. A follow-up CT scan in one of our two cases with coeliac disease demonstrated complete resolution of the intussusception, supporting the transient nature of this entity in adult coeliac disease. The exact mechanism is not fully understood, but is felt to be related to the loss of normal tone in the small bowel brought on by the toxic effect of gluten. The flaccid and dilated bowel loops are more prone to non-obstructing intussusception [13]. Intussusception may also be caused by gastrointestinal manifestations of AIDS. These include lymphoma, lymphoid hyperplasia, CMV colitis or Kaposi sarcoma [4,14,15]. Therefore, intussusception should be considered in patients with AIDS with prolonged abdominal pain. In conclusion CT is a sensitive examination to diagnose intussusception. The lead point can be diagnosed with
9 1998 The Royal Collegeof Radiologists,ClinicalRadiology, 53, 53-57.
57
certainty only in cases of lipoma. In those cases where a lipoma is not demonstrable, malignant lesions underlie a considerable proportion and in these, CT provides an excellent pre-operative evaluation, including possible extension and/or dissemination of a malignant tumour.
REFERENCES 1 Agha FP. Intussusception in adults. American Journal of Roentgenology 1986;146:527-531. 2 Merine D, Fishman EK, Jones B, Siegelman SS. Enteroenteric intussusception: CT findings in nine patients. American Journal of Roentgenology 1987;t48:1 t29-1132. 3 Bar-Ziv J, Solomon A. Computed tomography in adult intussusception. Gastrointestinal Radiology 1991;16:264-266. 4 Lorigan JG, DuBrow RA. The computed tomographic appearances and clinical significance of intussusception in adults with malignant neoplasms. British Journal of Radiology 1990;63:257-262. 5 Iko BO, Teal JS, Siram SM, Chinwuba CE, Roux VJ, Scott VF. Computed tomography of adult colonic intussusception: clinical and experimental studies. American Journal of Roentgenology 1984; 143:769-772. 6 Donovan AT, Goldman SM. Computed tomography of ileocecal intussusception: mechanism and appearance. Journal of Computer Assisted Tomography 1982;6:630-632. 7 Parienty RA, Lepreux JF, Gruson B. Sonographic and CT features of ileocolic intussusception. American Journal of Roentgenology 1981;136:608-610. 8 Gourtsoyiannis NC, Papakonstantinou O, Bays D, Malamas M. Adult enteric intussusception: Additional observations on enteroclysis. Abdominal Imaging 1994;19:11-17. 9 Yoshimitsu K, Fukuya T, Onitsuka H et al. Computed tomography of ileoileocolic intussusception caused by a lipoma. Journal of Computer Assisted Tomography 1989;13:704-706. 10 Felix EL, Cohen MH, Bemstein AD, Schwartz JH. Adult intussusception. Case report of recurrent intussusception and review of the literature. American Journal of Surgery 1976;131:758-761. i1 Marshak RH, Lindner AE. Radiology of the Small Intestine. London: Saunders, 1970:23-26. 12 Cohen MD, Lintott DJ. Transient small bowel intussusception in adult coeliac disease. Clinical Radiology 1978;29:529-534. 13 Strobl PW, Warshauer DM. CT diagnosis of celiac disease. Journal of Computer Assisted Tomography 1995;19:319-320. 14 Silverman PM, Hayes WS, Cooper CJ et al. Abdominal case of the day. American Journal of Roentgenology 1990;154:1325-1330. 15 Wood BJ, Kumar PN, Cooper C, Silverman PM, Zeman RK. AIDSassociated intussusception in young adults. Journal of Clinical Gastroenterology 1995;21:158-162.
Intussusception in Adults: CT Diagnosis G. GAYER, S. APTER, C. HOFMANN, S. NASS, M. AMITAI, R. ZISSIN* and M. HERTZ
Departments of Diagnostic Imaging, The Chaim Sheba Medical Center, Tel Hashomer and *Sapir Medical Centre, Kfar Saba, Affiliated to the Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel Purpose: Intussusception in adults is nowadays usually diagnosed on computed tomogr a p h y (CT), as CT is often the first modality for the investigation of prolonged abdominal pain f r o m which these patients suffer. We wish to present the CT, clinical and pathological findings of 16 adult patients with intussusception seen over a 5-year period. Materials and Methods: The abdominal scans of 16 patients with intussusception were reviewed. Special attention was directed to the location of the mass, its shape and fat content, possible underlying pathology and dilatation of the bowel proximally. The findings were correlated with clinical and pathological data. Results: Eight men and eight women, aged 34-81 years, were studied. The most frequent indication for CT was prolonged abdominal pain. CT findings included an inhomogeneous soft tissue mass, target or sausage-shaped, depending on the angle of the CT beam vs. the intussusception, with a fatty component in 14 of the 16. Intussusception was enteroenteric (six), ileocolic (three), or colocolic (seven). Complete small bowel obstruction was present only in one case and some bowel dilatation in three. The underlying pathology could be diagnosed on CT in only two cases of lipoma. Nine patients had an underlying malignant process, eight of them unsuspected. Of the other five, two had coeliac disease, two were classified as idiopathic and one had a necrotic polyp of undetermined pathology. Conclusion: Intussusception on CT presented a characteristic mass lesion containing fat stripes in almost all patients. Obstruction was rarely seen. Malignant lesions were the most common cause and therefore early diagnosis and p r o m p t intervention are essential. Gayer, G., Apter, S., Hofmann, C., Nass, S., Amitai, M., Zissin, R. & Hertz, M. (1998). Clinical Radiology 53, 53-57. Intussusception in Adults: CT Diagnosis
Accepted for Publication 8 April 1997
Intussusception is defined as telescoping of one segment of the gastrointestinal tract into an adjacent one. It is a relatively common entity in childhood in which it presents as an acute illness. In adults, it is manifested most often by chronic abdominal pain. The use of CT as the first imaging modality in the evaluation of patients with abdominal complaints has greatly expanded over the last few years. The radiologist is therefore often the first to suggest the diagnosis of intussusception in a patient with chronic abdominal pain referred for CT. We wish to report 16 adult patients with emphasis on the CT findings and corroborated by clinical and pathological data.
M A T E R I A L S AND M E T H O D S The imaging studies and clinical records of 16 patients diagnosed by CT as having intussusception of the small intestine or colon were retrospectively reviewed. CT was the initial examination to suggest the diagnosis in 14 patients, and it was the only study in 10. In two patients CT was performed after an ultrasound examination raised the possible diagnosis of intussusception. In one patient a barium enema preceded CT, but the intussusception was missed as reduction occurred during the exam. Barium enema was performed in two cases after the CT diagnosis. Correspondence to: Dr G. Gayer, Department of Diagnostic Imaging, Sheba Medical Centre, Tel Hashomer 52621, Israel. 9 1998 The Royal College of Radiologists.
An upper gastrointestinal tract study was performed after CT in three cases. Laparotomy was performed in 13 patients and the intussuscepted bowel segment was resected in 12 patients. CT scans were obtained on either the Elscint 2400 Elite or on the Elscint CT Twin with a scanning time of 2.1 s or 1.1 s and 10 mm collimation with scans at 1.0 cm intervals from the diaphragm to the symphysis pubis and additional scans as needed. Oral contrast material, 500 ml of flavoured solution of 4% Telebrix (meglumine-ioxitalamate) was administered 2 h before the examination and an additional 250 ml just before the study. Intravenous contrast material was used routinely, unless contraindicated by clinical history. Air insufflation per rectum was performed in one case. RESULTS Table 1 shows the relevant clinical, radiological and pathological data of the 16 patients (eight male, eight female) with intussusception. Ages ranged from 34 to 81 years (mean age 58 years). The most frequent indication for CT was prolonged abdominal pain (of several weeks' or even months' duration). Other symptoms and signs included weight loss, constipation and an abdominal mass at physical examination. Five patients had relevant clinical histories: two patients had a known malignant disease; one melanoma (case 9) and one metastatic carcinoma of the stomach (case 16). A third patient (case 7) had undergone nephrectomy for a malignant
54
CLINICAL RADIOLOGY
Table 1 - Main clinical radiological and pathological findings in 16 patients with intussusception
Case
Sex
Age Clinical data (years)
1
F
55
2
M
80
3 4
M F
34 66
5
F
40
6
F
79
7 8
F M
70 34
9
M
10
M
Pathology
CT findings Target or sausageshaped
Fat crescent
Rim of contrast material
Air bubbles in periphery
Bowel dilatation
Coeliac disease, abdominal pain Anaemia, colonoscopy: obstructing lesion Coeliac disease Abdominal pain, fever, leukocytosis Abdominal pain prolonged, abdominal mass Prolonged abdominal pain, abdominal mass
+
+
+
+
-
+
+
+
-
_
+
+
-
+
+
+
+
-
+
+
+
+
+
-
_
Cancer of descending colon
Haemorrhagic necrosis in ascending colon Large cell lymphoma in terminal ileum and caecum Cancer of caecum Cancer of ascending colon Malignant melanoma jejunum Lipoma in sigmoid colon
Abdominal pain
+
+
+
-
_
Abdominal pain, vomiting
+
+
-
-
bowel obstruction
70
Malignant melanoma palpable abdominal mass in L L Q
+
+
+
+
-
47
Abdominal pain RLQ
+
+
-
+
-
Necrotic polyp in terminal ileum White plaques on serosal surface of small bowel Lymphoma in jejunum
Small
recurrent intestinal obstruction 11
F
81
Abdominal pain
+
+
+
-
_
12
M
55
+
+
+
-
_
13
M
48
+
+
+
+
-
14
F
74
_
_
+
+
+
15
F
56
Anaemia, melaena, Upper gastrointestinal bleeding Abdominal pain, weight loss Abdominal pain, constipation, weight loss Prolonged abdominal p a i n
+
+
-
_
_
16
M
36
Cancer of stomach, Abdominal p a i n
+
+
+
-
_
tumour 6 years earlier without evidence of metastatic spread. The last two patients had biopsy-proven coeliac disease (cases 1 & 3). None of these patients had undergone previous surgery of the gastrointestinal tract. Laparotomy was performed in 13 patients and a lead point was found on pathological examination in 11. In one patient (case 11) with small bowel intussusception on CT, bowel resection was not performed and in another patient (case 4), a colocolic intussusception was found at surgery and histologically areas of haemorrhagic necrosis in the wall of the ascending colon were seen but no mass lesion. A repeat colonoscopy 5 months later revealed findings consistent with acute colitis. Of the three patients who did not undergo surgery, two (cases 1 & 3) had biopsy-proven coeliac disease; in case 1 a follow-up CT demonstrated resolution of the condition and patient 3 was lost to follow-up and non-obstructing intussusception of the small bowel was attributed to the underlying coeliac disease. The third patient (case 16) had a history of disseminated metastatic carcinoma of the stomach which was presumed to be the cause of the enteroenteric intussusception. Underlying pathological processes causing the intussusception included carcinoma of the colon in four patients, lymphoma in three (one involving the terminal ileum and caecum, one ileum and one jejunum) and one melanoma metastasis in the jejunum. Two had benign lesions, both lipomas, one in the caecum and the other in the signoid. One
Lipoma ascending colon Cancer of transverse colon Lymphoma in ileo-caecal valve Assumed metastases from gastric cancer
patient had a polypoid lesion in which marked necrosis made a final diagnosis as to its benign or malignant nature impossible (case 10). Intussusception was diagnosed on CT in all 16 patients. The most common finding was a thickened segment of bowel with an eccentrically placed crescent-like fatty area, representing the intussusception and the intussuscepted mesentery (14 cases). This appeared either as a round target mass (Fig. 1) (nine cases) or as an oblong sausageshaped mass (Fig. 2) (two cases) and in three cases both configurations, at different levels depending on the angle of the CT beam vs. the intussusception. The second most common finding was a rim-shaped accumulation of contrast material in the periphery of the mass (Fig. 3). This was present in 11 patients and enabled us to make the diagnosis in the two cases in which the typical crescent-like fat stripe was not demonstrated. In one of the five cases in which this sign was absent the small bowel was totally obstructed. In two cases the contrast material had not reached the intussusception and in another two cases despite passage of contrast material beyond the lesion, a 'rim' was not present. Additionally air bubbles in the uppermost part of the intussusception were observed in seven cases. These air bubbles were proven to be intraluminal and not intramural following rectal insufflation in one case (Fig. 4a, b). In two cases a well-marginated, round homogeneous intraluminal mass with a fat density was demonstrated, characteristic of lipoma (Fig. 5a, b). 9 1998
The Royal College of Radiologists, Clinical Radiology, 53, 53-57.
INTUSSUSCEPTION IN ADULTS
Fig. 1 - Case 3. A round mass lesion in the left lower abdomen consisting of thickened bowel walls with eccentric low density mesenteric fat (arrowhead) within it. A small air bubble is present in the upper part of the loop (arrow). Some dilatation of the small bowel is also seen.
55
(a)
(b) Fig. 2 - Case 10. An elongated mass lesion of soft tissue with fatty tissue within it in the right iliac fossa. Thin soft tissue strands within the fat (arrows) represent mesenteric blood vessels within the invaginated mesenteric fat.
Fig. 3 - Case 1. A round target-shaped mass consisting of different densities is seen in the left mid-abdomen. A peripheral rim of contrast material (curved arrow) with an air bubble on top (arrow) represents the space between the opposing bowel walls of the intussusceptum and the intussuscipiens. A 'half moon'-shaped fatty density (arrowhead) is seen in the centre of the lesion adjacent to a round dense area (open arrow) representing the intussuscepted mesentery and bowel, respectively. 9 1998 The Royal College of Radiologists, Clinical Radiology, 53, 53-57,
Fig. 4 - Case 5. (a) A complex mass lesion (long arrows) of soft tissue surrounded by fluid and some eccentric fatty density tissue. At the upper part of the lesion a few air bubbles (short arrow) are noted. (b) Scan following air insufflation per rectum demonstrates a lobulated inhomogeneous mass surrounded by a large amount of air (arrows) within the lumen of the colon at the splenic flexure.
Additional findings on CT were: a small amount of ascites (two cases), liver lesions (two patients, in one this proved on pathology to be involvement by lymphoma which was also the cause of the small bowel intussusception) and multiple lung nodules suspected to be metastases in four cases (two with carcinoma of the colon, one with melanoma, and another one with melanoma but the intussusception was caused by a lipoma). Three patients had some bowel dilatation proximal to the intussusception and one single patient had complete small bowel obstruction at the level of the intussusception. Upper gastrointestinal tract studies performed in three patients demonstrated respectively a complete obstruction (in a case of melanoma), an ileocolic intussusception (in a case of lymphoma) and areas of destroyed mucosa without definite evidence of intussusception (in another case of lymphoma). The intussusceptions were: enteroenteric (six), ileocolic (three) and colocolic (seven). Their aetiologies are summarized in Table 2.
56
CLINICAL RADIOLOGY
DISCUSSION
(a)
(b) Fig. 5 - Case 13. (a) An invaginating bowel loop (curved arrow) is seen entering a soft tissue mass (open arrows) with at its tip a round mass of fatty density surrounded by a thin rim of contrast material (wide arrow). (b) A scan 2 cm more caudally demonstrates clearly a round, well-demarcated lipoma surrounded by contrast material (arrow). Note the soft tissue density (open arrows) adjacent to the lipoma.
Table 2 - Underlying pathology and localization of intussusception in 16 cases
Underlying pathology
Localization Enteroenteric
Total lleocolic Colocolic
Benign Coeliac disease Lipoma
2
Malignant Carcinoma Lymphoma Melanoma metastasis Carcinoma metastasis
1 1 1
Idiopathic Undetermined
1
Total
6
1 1 3
7
2 1 16
Intussusception is rare in adults when compared with children and has a demonstrable cause in 90% of cases [1]. These patients are nowadays most often diagnosed on CT. Benign or malignant tumours account for ~ 65% of the underlying pathology [1]. The CT appearance of intussusception is characteristic and has been confirmed experimentally in animal models and proven clinically [2-7]. The major CT features in our series were similar to those previously described including: (1) An apparent mass lesion, caused by a thickened segment of bowel, the intussusceptum telescoping into the intussuscipiens. (2) A crescent-like, eccentric low attenuation fatty mass, representing entrapped mesenteric fat. The combination of these two features produces a target or sausageshaped mass, depending on the angle of the CT beam vs. the intussusception. (3) A rim of contrast material encircling the intussusceptum, representing coating of the opposing bowel walls of the intussusceptum and intussuscipiens. This feature is analogous to the coil spring sign of intussusception, seen on a barium enema [6]. This sign enabled us to make the diagnosis in the two cases in which mesenteric fat was not visualized within the mass. (4) Air bubbles peripheral to the upper part of the intussusception, which just like contrast material may enter between the opposing bowel walls. The location of these bubbles should not be confused with intramural air which reflects vascular compromised bowel. Intraluminal air tends to accumulate uppermost when the patient is examined in the supine position [3], whereas intramural air can appear anywhere in the periphery of a mass lesion. (5) A leading mass was infrequently seen in our study as only two cases of lipoma were identified with certainty on CT. CT provided confident identification of intussusception in all 16 cases but the exact aefiology could not be determined with certainty except in the cases of lipoma, which presented as well-marginated, round homogeneous masses with a density of fat content, unlike the mesentefic, peripherally placed fat seen in entrapped mesenteric fat. Benign and malignant causes of intussusception could not be distinguished on CT in this and other series [2,6,7-9]. One of our cases with colonic lipoma as a leading mass (case 13) showed a prominent soft tissue mass adjacent to the lipoma. This was also described by Donovan et al. [6]. This soft tissue pseudotumour represents the intussusceptum itself and not the leading mass. The other patient with a lipoma as a lead point (case 9) had been treated for melanoma, but the intussusception was unrelated to the known malignancy. A similar case of a lipoma in a patient with two primary neoplasms was reported by Lorigan et al. [4]. Thus, even in patients with known malignancy, intussusception may be caused by a benign process. In three cases there was some dilatation of the bowel proximal to the intussusception, and in one case a jejunojejunal intussusception caused complete obstruction. In the other 12, the proximal bowel loops were normal. The absence of bowel obstruction may account for the chronicity of the condition. The lack of proximal bowel dilatation in most of our patients is in contrast to a report of nine patients, all of whom showed some proximal bowel dilatation [2]. In a review of 25 adults with intussusception Agha classified them according to their aefiology as: tumourrelated (13 cases), postoperative (nine cases), miscellaneous (one case) and idiopathic (two cases) [1]. 9 1998 The Royal College of Radiologists, ClinicalRadiology, 53, 53-57.
INTUSSUSCEPTION IN ADULTS
In our series too, the majority of patients (12 out of 16) had an underlying tumour (nine malignant, two benign and one necrotic polyp). These were about evenly distributed in the small and large bowel. The incidence of underlying malignancy of the small bowel in intussusception is usually reported to be much less [9,10] than in this small series (five of nine). We encountered no patients with a postoperative intussusception, although this was the experience in nine out of 25 cases reported [1]. We classified two of our cases as idiopathic: in case 11 with an enteroenteric intussusception, no intussusception was found at laparotomy but only white plaques were seen on the serosa, and bowel resection was not performed. The other patient (case 4) underwent fight colectomy and areas of haemorrhagic necrosis in the wall of the colon were observed, but no mass lesion was present. Two patients with enteroenteric intussusception had coeliac disease. There are only a few case reports of intussusception in this disease. Marshak and Lindner stated that intussusception is not uncommon in coeliac disease, but that it is easily missed due to its transient nature [11]. Cohen and Lintott reported six adult coeliac patients with transient nonobstructing intussusception of the small bowel on a barium meal [12]. They stated that it occurs in at least 20% of adults with coeliac disease, and considered it an additional radiological sign in the diagnosis of coeliac disease. A follow-up CT scan in one of our two cases with coeliac disease demonstrated complete resolution of the intussusception, supporting the transient nature of this entity in adult coeliac disease. The exact mechanism is not fully understood, but is felt to be related to the loss of normal tone in the small bowel brought on by the toxic effect of gluten. The flaccid and dilated bowel loops are more prone to non-obstructing intussusception [13]. Intussusception may also be caused by gastrointestinal manifestations of AIDS. These include lymphoma, lymphoid hyperplasia, CMV colitis or Kaposi sarcoma [4,14,15]. Therefore, intussusception should be considered in patients with AIDS with prolonged abdominal pain. In conclusion CT is a sensitive examination to diagnose intussusception. The lead point can be diagnosed with
9 1998 The Royal Collegeof Radiologists,ClinicalRadiology, 53, 53-57.
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certainty only in cases of lipoma. In those cases where a lipoma is not demonstrable, malignant lesions underlie a considerable proportion and in these, CT provides an excellent pre-operative evaluation, including possible extension and/or dissemination of a malignant tumour.
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