Pericolic Fat Research Articles

Caecal Carcinomas in the Elderly: Useful Signs in Minimal Preparation CT

OBJECTIVE: Frail, elderly and immobile patients frequently have difficulty in tolerating formal colonic investigations. Caecal tumours may account for up to 35% of colonic tumours. Barium enema and colonoscopy have limitations in assessing this region. The aims of this study were to evaluate the accuracy of a minimal preparation CT technique (merely with prolonged oral contrast medium) in identifying caecal carcinomas and to determine helpful radiological signs. MATERIALS AND METHODS: The CT technique involved helical acquisition following 2 days of preparation with oral contrast medium. The outcome of 4 years' experience (1995–1998) was reviewed. The gold-standards were pathological and cancer registration records, together with colonoscopy and barium enema where available, with a minimum of 15 months' follow-up. RESULTS: CT correctly identified 27 of 30 caecal carcinomas, and missed three, in a total of 1077 CT studies in 1031 patients (median age 80 years). There were also 21 false-positive cases in which CT incorrectly raised the possibility of a caecal tumour. The sensitivity, specificity, negative predictive value (NPV) and positive predictive value (PPV) were 90%, 98%, 99% and 56%, respectively. Serosal margin blurring, tumour length, presence of abnormal peri-colic fat and terminal ileal wall thickening were identified as useful radiological signs. CONCLUSIONS: Minimal preparation CT is able to identify caecal carcinomas with fair accuracy. Such evaluation may become important given the increasing population age and evidence of a ‘proximal shift’ in the site of colonic tumours in the elderly. Ng, C. S.et al. (2002). Clinical Radiology57, 359–364.

Histopathological correlates of abnormal pericolic fat on CT in the assessment of colorectal carcinoma.

The aim of this study was to assess the pathological significance of abnormal pericolic fat shown by CT in the context of colorectal carcinoma. CT and histopathological findings of 63 resected colorectal carcinomas were retrospectively reviewed. CT examinations were assessed by two observers for the presence or absence of abnormal pericolic fat (typically linear or nodular opacities) at tumour sites. Specimens were reviewed histopathologically for depth of tumour invasion, extramuscular tissue reaction, and number and largest size of tumour-involved and tumour-free lymph nodes. The sensitivity, specificity, positive predictive value and negative predictive value of pericolic fat in identifying extension of tumour infiltration beyond the muscle coat were 79% (42/53), 33% (2/6), 91% (42/46) and 15% (2/13), respectively. Despite these indicators of efficacy, the association between the presence of pericolic fat abnormality on CT and extramuscular extension of tumour (infiltration and/or nodal disease) or tissue reaction alone or in combination did not reach statistical significance (p>0.3 in all cases). Abnormal ("misty" or "mucky") pericolic fat in the assessment of colorectal cancer on CT is not a precise indicator of extramuscular extension of tumour, as it cannot clearly distinguish between tumour infiltration and tissue reaction beyond the muscle coat, or pericolic nodal involvement. However, it is a very helpful CT sign that may draw attention to the presence and site of a potential colonic abnormality.

Malakoplakia in association with colorectal carcinoma: a series of four cases

Malakoplakia is a characteristic inflammatory condition which is usually seen in the urogenital tract. Gastrointestinal malakoplakia is seen in association with a variety of conditions such as ulcerative colitis, diverticular disease, adenomatous polyps and carcinoma. The purpose of this paper is to report four additional cases of colorectal cancer associated with malakoplakia and review the literature on this association. All specimens were colectomies for cancer. Routine handling of the specimen with lymph node harvesting was performed. In addition to H&E stains, PAS, Perls' Prussian Blue and von Kossa stains were performed. Three of the cases were encountered in males and the patients ranged in age from 55 to 64 years. One case each occurred in the caecum/ascending colon and descending colon, while the remaining two were located in the rectum. All four cases were Dukes' stage B tumours. Furthermore, all four cases had spread to pericolic fat and two had perforated. Microscopic examination showed the malakoplakia to be present at the infiltrating edge of the tumours. The draining lymph nodes were involved by malakoplakia to varying degrees in all cases. From this series and the literature review, malakoplakia associated with colorectal cancer tends to occur in elderly males in the rectum. The malakoplakia is found at the infiltrating front of the tumour and is not admixed with the neoplastic glands. Although lymph node involvement by malakoplakia has been reported only once previously, all four cases in this series showed evidence of involvement. The association does not appear to have any prognostic significance.

Ectopic prostate: case report of a presacral mass presenting with obstructive symptoms.

○ We report the unusual case of a 78-year-old man who presented with obstructive bowel symptoms and a 2.5-cm presacral mass. The mass was excised and found on pathologic examination to be ectopic prostate tissue complete with a muscular stroma. Review of the literature revealed a number of case reports describing variably sized fragments of ectopic prostate tissue involving a variety of organs, including spleen, uterine cervix, bowel wall, pericolic fat, anal submucosa, seminal vesicle, testis, and urinary bladder. However, to our knowledge, this case is unique in that it presented as a relatively large, isolated presacral mass causing functional bowel impairment. The ectopic location can be related to the normal embryonic development of the prostate, rectum, and bladder.

Sonography of acute right side colonic diverticulitis

Background: To describe the prevalence and sonographic findings and ultrasound diagnostic accuracy of the right side colonic diverticulitis in patients having right lower abdominal pain with indeterminate nature. Methods: A total of 934 patients with acute right lower abdominal pain of clinically indeterminate nature were referred for ultrasound examination (US). US studies were performed with 3.5 to 7.0 (or occasionally 10) MHz transducers using graded compression method. Twenty-three patients were finally diagnosed to have an uncomplicated acute diverticulitis of the right colon. The gray-scale sonographic images were reviewed. A retrospective study was undertaken to evaluate diagnostic contribution of US. Results: The prevalence of acute right side colonic diverticulitis was 2.5% in patients with clinically indeterminate acute right lower abdominal pain. Locations of the inflamed diverticula include cecum in 6 patients, proximal ascending colon in 15 patients, and distal ascending colon in only 2 patients. Sonography detected 21 inflammed diverticula with 1 false positive and 2 false negative results. The most typical sonographic feature of an inflamed diverticulum of right side colon was a rounded or oval-shaped hypoechoic or nearly anechoic structure (52%) protruding out from the segmentally thickened colonic wall. Some of them might contain strong echoes representing gas or feces (43%), or stone in the lumen (5%). Regional pericolic or peridiverticular fat thickening was noted in 57% of patients, and segmental colon wall thickening in 38%. US examination yielded a sensitivity of 91.3%, a specificity of 99.8%, an overall accuracy of 99.5%, a positive predictive value of 95.5%, and a negative predictive value of 99.7%. A positive sonogram made the likelihood of acute right side diverticulitis 456.5 times greater compared with the pretest clinical impression. US differentiated acute right side colonic diverticulitis from acute appendicitis with a 100% accuracy. Conclusions: Ultrasound can be extremely useful in diagnosing acute right side colonic diverticulitis. Careful ultrasound evaluation of the right colon and the cecum may facilitate a correct diagnosis and help differentiate from acute apprendicitis, and steer the surgeon to a more effective management.

Spiral CT of colon cancer: imaging features and role in management.

Colorectal cancer is a common malignancy that results in significant morbidity and mortality. Abdominal computed tomography (CT) is valuable in planning surgery for colon cancer because it can demonstrate regional extension of tumor as well as adenopathy and distant metastases. At CT, colorectal cancer typically appears as a discrete soft-tissue mass that narrows the colonic lumen. Colorectal cancer can also manifest as focal colonic wall thickening and luminal narrowing. Complications of primary colonic malignancies such as obstruction, perforation, and fistula can be readily visualized with CT. At CT, local extension of tumor appears as an extracolic mass or simply as thickening and infiltration of pericolic fat. Extracolic spread is also suggested by loss of fat planes between the colon and adjacent organs. The liver is the predominant organ to be involved with metastases from colorectal cancer. At CT, hepatic metastases usually appear as hypoattenuating masses, which are best visualized during the portal venous phase of liver enhancement. Other common sites of metastases from colon cancer include the lungs, adrenal glands, and bones. Use of CT is critical for identifying recurrences, evaluating anatomic relationships, documenting "normal" postoperative anatomy, and confirming the absence of new lesions during and after therapy.

The accordion sign at CT: a nonspecific finding in patients with colonic edema.

To determine whether the "accordion sign" is a specific computed tomographic (CT) sign of Clostridium difficile colitis. Fifty-seven patients with CT evidence of severe colitis, as judged by colonic wall thickening, an abnormal haustral pattern, the target sign, and stranding of the pericolic fat, were identified from a computerized CT database for 25 months. CT images were retrospectively evaluated for the presence of oral contrast material in the colon and for the accordion sign. The medical and laboratory records of all patients were reviewed and correlated with CT findings to establish the cause of colitis. Oral contrast material had reached the colon in 35 of 57 patients at the time of the CT examination. The images in 15 of these patients demonstrated the accordion sign, and those in 20 patients did not. C difficile colitis was documented in four of the 15 cases displaying the accordion sign. In the remaining 11 patients, a different cause was documented. Oral contrast material had not reached the colon in the remaining 22 patients. Within this group with findings similar to the accordion sign, five patients had documented C difficile colitis, and four had colitis from other causes. The accordion sign is indicative of severe colonic edema or inflammation, but it is not specific for C difficile colitis.

Author reply

We thank Dr. Cserni for his interest and comments on our article. We would like to develop certain points he discussed. In France, where colorectal carcinoma is managed with a decentralized health care system, studies of health care practices must be population-based to be representative. In that way, our study is free of the types of selection biases that usually limit conclusions drawn from data collected in specialized centers. Contrary to Dr. Cserni's suggestion, we did not apply a preexisting mathematic model to our data. First, we established a sample of resected colorectal carcinomas representative of routine and current practices in France and then we investigated by logistic regression the relation between the regional lymph node classification of the tumor (i.e., N+ vs. N−) and the number of lymph nodes examined. Dr. Cserni wondered how 65 patients in whom no lymph nodes were recovered could be classified; in fact, they were excluded from further analysis. We agree with Dr. Cserni that not all but many lymph nodes with metastases are enlarged and thus easier to recover from the pericolic fat. In spite of the influence of many factors such as the variability of the host-tumor response, the heterogeneity of surgical and pathologic practices is likely to be the chief explanation for the variations in the number of lymph nodes examined, with the mean value for each department showing a wide range in our study, as it did for each hospital in the Large Bowel Cancer Project study.1 With regard to the “less than optimal” category (not enough lymph nodes examined), at least two survival studies (Givel et al., unpublished data and ref. 2) already have demonstrated an independent effect of the number of lymph nodes examined, with a plateau number very close to the one determined in our study. One limitation of our study was the lack of available precision regarding the location of positive lymph nodes; however, after the completion of our work we observed that the latest edition (1997) of the TNM staging system did not take into account the location of positive and examined lymph nodes. Finally, the validity of our statement that at least eight lymph nodes should be examined to assess lymph node status correctly in colorectal carcinoma patients had been reinforced by the most recent French Consensus Meeting.3 Jean Maurel M.D., Ph.D.*, * Service de Chirurgie Digestive-CHu, Caen et Registre des Tumeurs, Digestives du Calvados, CJF INSERM, Caen, France

Computed tomography in acute left colonic diverticulitis.

The use of computed tomography (CT) in acute left colonic diverticulitis remains controversial. The purpose of this study was to define the value of CT both during the acute phase of inflammation and, later, to indicate secondary complications after successful medical treatment. Some 423 patients with radiologically or histologically proven diverticulitis were studied prospectively from 1986 to 1995. Diverticulitis was considered moderate when CT showed localized thickening of the colonic wall (5 mm or more) and inflammation of pericolic fat; it was considered severe when abscess and/or extraluminal air and/or extraluminal contrast were observed. The sensitivity of CT was 97 per cent. Of 42 patients who failed conservative treatment, 32 had severe diverticulitis on CT, compared with 74 (24 per cent) of 303 who had successful conservative treatment (P < 0.0001). After a median follow-up of 46 months, 60 (20 per cent) of 300 patients had secondary complications despite initially successful conservative treatment: 28 (47 per cent) of these had initial severe diverticulitis on CT compared with 44 (19 per cent) of 236 patients who had no complications (P < 0.0001). Abscess formation and extracolonic contrast or gas are findings that may be used to predict failure of medical treatment during the first admission and a high risk of secondary complications after initially successful medical management of acute diverticulitis.

Diagnosis of Diverticulitis

Between 15 and 30% of patients with colonic diverticula subsequently develop diverticulitis. Plain abdominal films and contrast enema are of limited diagnostic use in diverticulitis because of their overall low sensitivity and specificity. Ultrasound although potentially a powerful addition, is limited by the small field of view, bowel air and the experience needed for using it. Computed tomography (CT) has had significant impact on the diagnosis, staging and management of patients with diverticulitis. The key feature in diagnosis of diverculitis is inflammation of pericolic fat (in up to 98%), often coupled with extraluminal air, the presence of diverticula and colonic wall thickening. At the same time, CT reliably demonstrates abscesses and extraperitoneal complications of diverticulitis.

Impact of the Crohn's-like lymphoid reaction on staging of right-sided colon cancer: Results of multivariate analysis

The presence of lymphoid aggregates within the muscularis propria or pericolic fibroadipose tissue apposing invasive colorectal carcinoma, termed the Crohn's-like lymphoid reaction, has been related to improved patient length of survival according to univariate statistical analysis. We tested the Crohn's-like lymphoid reaction as an indicator of prognosis in a multivariate statistical analysis of 344 resected right-sided colonic cancers. Improved 5-year survival in univariate analysis was associated with low tumor grade, regular tubule configuration, expanding tumor growth pattern, prominent peritumoral lymphocytic infiltration, absence of tumoral invasion of extramural veins, all levels of intramural and extramural invasion short of widespread local tumor permeation, conspicuous Crohn's-like lymphoid reaction, and absence of both nodal metastasis and nodal-independent tumor nodules in pericolic fat. By the Cox proportional hazard model using the stepwise method, depth of tumor invasion, lymph node metastasis, Crohn's-like lymphoid reaction, and metastatic tumor nodules in pericolic fat retained independent prognostic significance. Combining the four variables to formulate pathological prognostic categories yielded a highly favorable prognostic group—92% 5-year survival and 95% confidence limits (88% to 96%)—encompassing 53% of the study population. It included all Dukes' stage A carcinomas, 66% of Dukes' stage B adenocarcinomas, and 11% of Dukes' stage C cancers. Lymph node metastases coupled with intramural and extramural extent of tumor invasion are the cornerstones of colorectal cancer staging. Addition of other variables improves prognostication for the cecum and ascending colon. From this study the Crohn's-like lymphoid reaction and metastatic tumor nodules in pericolic fat emerge as significant independent indicators of prognosis for right-sided colon cancer. Complex correlations of both indicators with nonselected variables were observed.

From dukes through jass: Pathological prognostic indicators in rectal cancer

In the recently described Jass staging system for resected adenocarcinoma of the rectum, peritumoral lymphocytic infiltration and tumor growth pattern are introduced as significant indicators of prognosis in conjunction with depth of tumor invasion and lymph node metastasis. The authors of this study have tested the applicability of the Jass system by reviewing 348 resected rectal cancers for 12 pathological variables, including two newly recognized features, namely the Crohn's-like lymphoid reaction and metastatic tumor nodules in pericolic fat. By univariate analysis improved 5-year survival rate was associated with tubular-type adenocarcinoma, low tumor grade, retention of tubule configuration and nuclear polarity, expanding tumor growth pattern, prominent peritumoral lymphocytic infiltration, absence of extramural vein invasion by tumor, all levels of intramural and extramural invasion short of widespread local tumor dissemination, a Crohn's-like lymphoid reaction pattern, and absence of both nodal metastasis and tumor nodules in perirectal fat. By Cox stepwise proportional hazards analysis, depth of tumor invasion, lymph node metastasis, Crohn's-like lymphoid reaction, and extramural venous invasion retained independent prognostic significance. Peritumoral lymphocytic infiltration and tumor growth pattern of the Jass staging system failed to compete successfully with other variables in the proportional hazards model, in part because of their correlation with the model's selected variables. Both intramural and extramural extent of tumor invasion coupled with lymph node metastasis form the cornerstones of rectal cancer staging. However, other factors do refine prognostication. From this study the Crohn's-like lymphoid reaction emerges as a significant new independent indicator of prognosis for survival from rectal cancer. Although the Crohn's-like lymphoid reaction and extramural vein invasion took precedence as staging variables in this study, a complex interrelationship with other parameters was observed.

Colon carcinoid tumors

The aim of our investigation was to evaluate the clinical presentation of patients with carcinoid tumors of the colon and to estimate the survival and potential prognostic factors of this tumor type. A population-based study was performed using data from the Alberta Cancer Registry between 1964 and 1988 (inclusive). The clinical records and the pathologic material of eligible patients were reviewed. Survival was estimated both as crude survival and with the Kaplan-Meier method. During the 25-year study period (1964-1988), 36 true carcinoid tumors of the colon were diagnosed in Alberta. Carcinoids of the ileocecal region and of the rectum were excluded from the study. The average age at time of diagnosis was 68.4 years; there were 20 males and 16 females. Symptoms (abdominal pain, diarrhea, weakness, anorexia) occurred late in the course of the disease: 64 percent of the lesions were in Dukes D stage and 22 percent were Dukes C at diagnosis. Only one patient presented with a malignant carcinoid syndrome. Lesions occurred most frequently in the cecum (39 percent), followed by transverse and sigmoid colon. Most of the patients were managed surgically. The perioperative mortality rate was with 22 percent, which is quite high. The average size of the lesions was 5.8 (range, 2-10) cm, and most tumors (31/36) had invaded the pericolic fat. The most common immunohistochemical pattern was argentaffin/argyrophil negative and neuron-specific enolase positive. Two-year and five-year actuarial (Kaplan-Meier) survival was 34 percent and 26 percent, respectively. Survival for carcinoids of the colon was significantly lower compared with carcinoids of the rectum or appendix, and with colon adenocarcinomas. Size of the tumor and tumor invasion into the muscularis propria--the two major histopathologic prognostic factors for carcinoids of the gastrointestinal tract--were not found to influence survival significantly. Rather, tumor stage, histologic pattern, tumor differentiation, nuclear grade, and mitotic rate were found to significantly influence the survival rate. Carcinoid tumors of the colon are extremely rare tumors, diagnosed late in the course of the disease, and they carry a bad prognosis. Prognostic factors are tumor stage, histologic pattern, differentiation, nuclear grade, and mitotic rate of the tumor.

Appendices epiploicae of the colon: radiologic and pathologic features.

Appendices epiploicae are adipose structures protruding from the serosal surface of the colon. They can be seen with abdominal radiography and cross-sectional imaging if the colonic wall is surrounded by intraperitoneal contrast material, ascites, or blood. Normal appendices epiploicae appear as lobulated masses of pericolic fat, usually 2-5 cm long and 1-2 cm thick. Their enlargement, deformity, or altered radiopacity may result from various pathologic processes that can originate locally or extend from adjacent viscera. In a series of 22 cases, appendices epiploicae were affected by spontaneous torsion and hemorrhagic infarct, calcification due to aseptic fat necrosis, primary or secondary inflammation, enlargement by lipomas or metastases, and incarceration in hernias. Disorders of appendices epiploicae are often manifested by nonspecific clinical signs and symptoms (eg, torsion is often mistaken for appendicitis or diverticulitis). These entities should be included in the differential diagnosis of any unexplained abdominal pain or pericolic lesions in adults.

The value of sonography in the diagnosis of acute diverticulitis of the colon.

To assess the value of sonography as the initial imaging procedure in patients suspected of having acute diverticulitis of the colon, we evaluated the sonograms of 71 patients who had clinical signs and symptoms of the disease. Identification of diverticula on sonograms was taken as evidence of acute diverticulitis. Fifty-four patients had sonographic findings consistent with this diagnosis. These included gut wall thickening (53), diverticula (34), pericolic (21) and intramural (two) fluid collections, edema of the pericolic fat (22), and intramural sinus tract (one). The final diagnosis was based on the clinical impression (all cases); pathologic interpretation of a surgical specimen (33 cases); findings on contrast enema (40 cases), CT scan (14 cases), and colonoscopy (18 cases); and a favorable clinical outcome in the absence of therapy (17 cases). Forty-six of the 54 patients with positive sonograms had acute diverticulitis, six had pericolic inflammatory masses caused by other colonic diseases, and two had surgically confirmed diverticulosis without active inflammation. All 17 patients with normal sonograms were treated conservatively. Diverticulitis was not confirmed in any of these patients. Our study suggests that sonography is a valuable imaging technique in the patient with signs and symptoms of acute diverticulitis.

Is there any justification for the routine examination of bowel resection margins in colorectal adenocarcinoma?

The proximal and distal bowel resection margins of 339 specimens of colorectal adenocarcinoma were examined for the presence of tumour. In only five cases was tumour found in a resection margin. In four of these cases macroscopic examination showed that the tumour extended to the resection margin. In the fifth case the tumour was present in the pericolic fat. These results and reported data on the intramural spread of colorectal cancer suggest that examination of bowel resection margins is unnecessary unless the tumour extends to within 2 cm of the resection margin. Examination of the deep radial margins of the tumour and slides to show other prognostic indicators would be a more effective use of histopathological resources.

Diverticulitis of the right colon: CT observations.

Recent reports on the CT evaluation of patients with diverticulitis of the left colon prompted a retrospective review of the CT findings in six patients with diverticulitis of the cecum and ascending colon. All had pain and tenderness in the right lower quadrant. In each case, CT findings showed regional thickening of the colonic wall, an extraluminal mass involving the cecum and/or ascending colon, haziness and linear strands in adjacent pericolic fat, and thickening of nearby fascial planes. Extraluminal air was noted in four patients, and contrast-filled structures suggesting diverticula were present within the inflammatory masses of two. These results suggest that CT is a useful imaging tool in the diagnosis of right-sided diverticulitis.

Role of computed tomography in diverticulitis

Fourteen patients with diverticulitis who were clinically believed to require radiologic investigation form the basis of this report. An inflammatory mass (in = 10) or abscess (n = 2) were reliable findings on computed tomography. Other signs encountered were abnormal density of pericolic fat, thickening of colonic wall, and narrowing of the lumen of the colonic wall. Colovesical fistulas, all of which were suspected clinically, occurred in three patients. Computed tomography should be performed with administration of rectal contrast medium to demonstrate the origin of inflammation from the colon, assess pericolic extent, and confirm colovesical fistula.

Computed tomography in the evaluation of diverticulitis.

Computed tomography (CT) was performed in 43 cases of colonic diverticulitis and compared with the contrast-enema examination (CE) in 37 patients. Findings on CT included inflammation of the pericolic fat in 98% of cases, diverticula in 84%, thickening of the colon wall in 70%, a pericolic abscess in 35%, peritonitis in 16%, a fistula in 14%, colon obstruction in 12%, and intramural sinus tracts in 9%. Secondary findings included a distant abscess in 12% and ureteral obstruction in 7%. In addition to detecting ureteral and bladder involvement and distant abscess formation, CT was preferable for demonstrating the extent of pericolic inflammation, which was underestimated with CE in 41% of patients. Differential diagnosis of the CT findings is discussed. The authors indicate that CT should be the initial procedure in patients with suspected diverticulitis, particularly when CE is contraindicated.

Adjuvant therapy for dukes C adenocarcinoma of colon

Forty-two patients with adenocarcinoma of the colon, who received surgery between 1975 and 1978 and were to found to have pericolic fat infiltration and lymph node metastases, were analyzed for disease free period and overall survival. Twenty-one patients had received post-operative X ray therapy, and post-X ray therapy intravenous 5-Fluorouracil adjuvant therapy. Twenty-one patients, matched by age, sex, ethnic origin and site of disease were untreated. The 5 year survival rate for the treated group was 65 % compared with 36 % for the control group (P > 0.2). At 5 years 55% of the treated group were disease free but only 12% of the control group remained disease free (P = 0.04). The significance of this work needs to be established by a randomized and prospectively controlled clinical trial[/b]