Pablo R. Ros

Intussuscepted colonic lipomas: loss of fat attenuation on CT with pathologic correlation in 10 cases

Abstract.Background: To determine if infarction and necrosis is the cause of the confusing soft tissue density on CT within intussuscepting lipomas of the colon.nMethods: The clinical records, radiologic examinations, and pathologic specimens of all 13 cases of colonic lipomas collected from 1988 to 1994 studied by CT and surgically resected were retrospectively reviewed. Ten of these cases were associated with intussusception; the CT attenuation of the lead point was graded according to its relative fat/soft tissue density. Pathologic specimens were graded independently by a GI pathologist and graded according to the degree of infarction/fat necrosis.nResults: The lipomas ranged from 4 to 7 cm in diameter (mean = 5 cm). Only one case with intussusception, and all three cases without, demonstrated pure fat attenuation on CT and demonstrated pure fat histologically. One case demonstrated soft tissue attenuation and corresponded with the most severely infarcted specimen histologically; two cases with similar but less severe infarction/fat necrosis corresponded with less than 25% fat attenuation. These latter three cases were originally misinterpreted as malignancies rather than lipomas. Six cases maintained greater than 50% fat density and intermediate amounts of infarction/fat necrosis.nConclusion: Lipomas may have an atypical appearance when intussuscepted due to varying degrees of infarction/fat necrosis.

Encapsulated Hepatocellular Carcinoma: Radiologic Findings and Pathologic Correlation

The encapsulated form of hepatocellular carcinoma (HCC) is a pathologic subtype that has been found to occur with variable frequency in typical HCC in Japanese radiological, surgical, and autopsy series. It is a well-differentiated tumor that tends to grow slowly and noninvasively, and has a better prognosis than other gross forms of HCC.Among the 73 cases of typical HCC in patients of non-Asian extraction in our files, 11 could be positively identified as encapsulated based on strict pathological criteria. The purpose of this study was to review the radiographic appearance of these encapsulated tumors.Radiographically, the tumors demonstrated a hyperdense rim in 5 of 9 cases with postinfusion computed tomography scans, an anechoic halo in 4 of 6 cases with ultrasonograms, and an avascular rim on the capillary phase in 5 of the 8 cases with angiograms.Encapsulated HCC can be found in non-Asian patients, and the radiographic and pathologic findings are similar to the descriptions in the Japanese series.

Peritoneal mesothelioma : radiologic appearances correlated with histology

Previous imaging reports of peritoneal mesothelioma have described a variety of radiologic appearances, but have not included its pathologic classification. We retrospectively reviewed 10 cases of peritoneal mesothelioma representing the following histologic categories: 7 epithelial, 2 sarcomatoid, and one biphasic. By imaging, epithelial mesotheliomas demonstrated diffuse thickening of the peritoneum and mesentery and/or multiple small nodules. The sarcomatoid-type appeared as a mass and the biphasic-type had radiologic and gross pathologic features of both sarcomatoid and epithelial types. We conclude that peritoneal mesothelioma presents with a wide spectrum of radiographic appearances and should therefore be included in the differential diagnoses of diffuse as well as localized peritoneal processes.