Clinical study of 71 cases of colon cancer diagnosed by colonic pseudorenal sign
Abstract】Objective: To evaluate the diagnostic value of colonic ultrasound pseudorenal sign for colon cancer. Methods: Combined application of convex array and high-frequency linear array probe to observe the site of colonic pseudorenal sign, the involvement range, length, protrusion into and out of the lumen, the continuity of the outer membrane of the intestinal wall, the mucosal echogenicity, whether the surrounding lymph nodes are enlarged, whether the proximal intestinal canal of the lesion is dilated, and color Doppler to observe the blood flow characteristics, and combined with clinical symptoms and signs to make the diagnosis of benign and malignant lesions of the colon. All cases were confirmed by pathology. Results: 71 cases of colonic pseudonephritic sign, ultrasound suggested malignant in 64 cases, 59 cases were pathologically diagnosed as malignant, the ultrasound diagnostic compliance rate was 92.2%, false positive in 5 cases, and the misdiagnosis rate was 7.8%. Conclusion: Ultrasound pseudorenal sign has high diagnostic value for colon cancer.
【Key words】Ultrasound; pseudorenal sign; colon cancer
Colon cancer is a malignant tumor with gradually increasing incidence. It is not easy to detect clinically because there is no obvious discomfort in the early stage or the symptoms and signs lack specificity. [1] Over the years, due to the progress of ultrasound technology, certain experience has been accumulated in the ultrasound diagnosis of colon cancer. Endoluminal ultrasound and transrectal enema transabdominal examination have been able to show the whole tumor and used for tumor staging according to the degree of infiltration. However, in a large number of routine transabdominal examinations, the pseudonephritic sign found in each segment of the colon is still the main basis to suggest the diagnosis. In this paper, the diagnostic value of ultrasound pseudorenal sign for colon cancer was investigated by comparing 71 cases of routine colon pseudorenal sign with colonoscopic pathological examination and/or surgical pathology.
1. Materials and methods
1.1 General data: 71 cases were routine abdominal ultrasound patients from May 2000 to June 2006 in our hospital, aged 36-78 years old, with an average of 47 years old. Reasons for consultation: 31 cases of abdominal mass, 9 cases of pus and blood stool, 5 cases of anemia, the rest had no obvious clinical symptoms or only non-specific manifestations such as abdominal discomfort, poor appetite and wasting.
1, 2 Apparatus and methods: Esaote Techuos DU8 and HP-Lmage point color Doppler ultrasound diagnostic instruments from Esaote were applied, with frequencies of 2.5-5MHz convex array probe and 7-12MHz linear array probe used alternately. Adjust the gain and scanning depth appropriately. Starting from the ileocecal region or the deep surface of the appropriately filled bladder, the probe was swept continuously along the wavy, hyperechoic longitudinal surface of the colonic pouch according to the approximate body projection of the colon in the abdominal wall. After finding the lesion, the probe was moved laterally and rotated in multiple sections in the lesion area to observe the thickness of the lesioned intestinal wall, the extent of involvement, the manifestation of protrusion into and out of the lumen, the continuity of the outer lining of the intestinal wall, the echogenic condition of the mucosal surface and the presence of deformation or stenosis of the intestinal lumen, the enlargement or absence of enlargement of the surrounding lymph nodes, the presence or absence of obstructive dilatation of the intestinal canal proximal to the lesion, color Doppler flow presentation (CDFI) or to show the distribution of tumor blood flow, PW measurement Peak velocity and resistance index.
2. Results
All 71 cases of colon pseudorenal sign in this group were confirmed by surgery or colonoscopic biopsy pathology. There were 69 cases of colon cancer diagnosed by ultrasound, 7 cases (10.9%) were located in the ileocecal region, 19 cases (29.7%) in the ascending colon, 7 cases (7.8%) in the hepatic flexure of the colon, 3 cases (4.7%) in the transverse colon, 7 cases (10.9%) in the splenic flexure of the colon, 11 cases (17.2%) in the descending colon, and 13 cases (20.3%) in the sigmoid colon. Pathologically confirmed malignant tumors were found in 59 cases, including 47 cases of adenocarcinoma (79.6%) and 12 cases of mucinous carcinoma (20.3%). There were 5 false positive cases, all of which were located in the splenic flexure of the colon. Seven cases were diagnosed as benign lesions by ultrasound. Lesion characteristics: ① All were located in the ileocecal region and ascending colon, and three patients partially accumulated the adjacent ileum. The length of the pseudorenal sign, i.e., the cumulative intestinal length of the lesion, was >10 cm, including 5 cases of Crohn’s disease and 2 cases of ileocecal tuberculosis. The CDFI blood flow of the pseudonephritic sign was not abundant, and most of them did not detect colored blood flow, and in some cases, only sparse stellate blood flow was seen in the thickened intestinal wall, and there was no significant difference between benign and malignant.
3. Discussion
With the development of ultrasound technology and the progress of instruments and equipment, the value of ultrasound in diagnosing colon cancer has been recognized. The main basis of diagnosis is the pseudonephritic sign formed by irregular hypoechoic thickening of the intestinal wall and strong echogenicity of the inner lining with disorganized distribution in the center. [2] From the analysis of our data ultrasound presentation did not help in the identification and staging of the gross pathological type, and all types seen postoperatively and by colonoscopy showed a largely consistent pseudorenal sign. All the cases found were intermediate to late stage, indicating that the ultrasound display of early colon cancer was poor and could not achieve early diagnosis of colon cancer.
Generally speaking most malignant tumors have a rich arterial blood supply to accommodate their rapid growth. And the presence of tiny arteriovenous fistula can make the blood flow abnormally fast, and this feature of color multispectral became the basis of differentiating benign and malignant tumors. [3] None of the blood flow within the pseudorenal sign in this group of cases had these characteristics, and the reasons for this need to be further investigated.
The localization of the tumor-bearing intestine in this group of cases was not completely consistent with the surgical findings, although it was roughly comparable. The general pattern was that the lower part of the ascending colon was easily mistaken for the ileocecal tumor; the upper part of the ascending colon and the right part of the transverse colon were easily mistaken for the hepatic flexure tumor; the left part of the transverse colon and the upper part of the descending colon were easily mistaken for the splenic flexure tumor; while the lower part of the descending colon and the sigmoid colon tumor were not mistaken. The reason for this may be related to the stiffness and contracture of the local intestinal canal after aneurysm. The direction of contracture is the part of the intestinal canal that is relatively fixed in position.
In this group of 14 patients, polyps were found in the normal intestinal canal adjacent to the tumor after surgery, with a diameter of 0.5-2.3 cm, but none of them were found by ultrasound. This suggests that ultrasound has little diagnostic value for benign colon polyps. Conversely, the nodular occupying echogenicity of the colonic lumen found by ultrasound is not likely to be benign.
Ultrasound can measure the extent of tumor infiltration into the intestinal canal, while in a considerable number of cases, the tumor is so large and the intestinal lumen is so narrow that the speculum cannot pass through it, so that the whole picture of the tumor and the extent of involvement cannot be observed. Therefore, ultrasonography can be used as a supplement to speculum examination. In addition, ultrasound can simultaneously observe the infiltration of the tumor into the surrounding area, the metastasis of lymph nodes and distant organs, and the presence of ascites, which can provide valuable reference for the selection of clinical treatment plan.
It is worth noting that in 5 of the 7 cases diagnosed as splenic flexure colon cancer in this group, there were no abnormal findings in the speculum examination, the mucosa was regular, there was no stenosis in the intestinal lumen, there was no sign of external pressure, and no occupancy was seen in the lumen. The sonographic changes alone were indeed pseudorenal signs. The only difference is that the thickness of the thickened intestinal wall is more regular, and the echogenicity is slightly enhanced compared with that of colon cancer cases. The endothelial strong echogenic lines are longer and curved, which is slightly different from the disorganized distribution of short linear interruptions in colon cancer, and there are no metastatic signs in other parts of the body, the reasons for which need to be further discussed.
The cumulative intestinal tube lengths of the seven cases of pseudonephritis ultrasonically diagnosed as benign lesions in this group were all >10 cm, and combined with the fact that the patients had no evidence of distant metastases and were in fair general condition, the possibility of malignancy was estimated to be low. It is recommended that other relevant examinations be done to confirm this, suggesting that the diagnosis of colonic pseudorenal sign after discovery still requires close clinical integration, especially in those with a larger cumulative extent.
In conclusion, colonic pseudorenal sign has a high diagnostic value for colon cancer and can make up for the shortage of X-ray enema and speculum examination, especially for the detection of tumor in patients without obvious specific symptoms. There should be enough vigilance in daily work, and slightly expanding the scope of examination on the abdominal wall sometimes will make the clinical diagnosis much less detours, which has certain practical value.