Hyperechoic pseudotumors in segment IV of the liver.
Hyperechoic pseudotumors usually are considered "spared areas" in a fatty liver; they frequently are detected at the fourth hepatic segment close to the portal vein. Over a 3 year period, we observed 14 patients with a hyperechoic pseudotumor in otherwise normal livers; all of these lesions resembled a hyperechoic pseudotumor of the fourth segment with respect to site and morphology. In all cases echographic findings did not significantly change during the follow-up period ranging from 4 to 12 months. Computed tomographic examination was normal in two cases, whereas in the remaining 12 cases the hyperechoic lesion was appreciable as a hypodense area on both direct and dynamic scans; the contrast enhancement was never typical for a malignancy of a hemangioma. Six patients also underwent a color Doppler and power Doppler examination, which never demonstrated intralesional or perilesional abnormalities in the vascular signals. Three patients, who underwent surgery for adenocarcinoma of the large bowel, had intraoperative sonography and sonographically guided biopsy; a hepatic steatosis was diagnosed at histologic examination in all cases. The uniqueness of the cases presented here lies on the finding of focal steatosis at a site where, according to the most credible hypothesis, intracellular deposition of triglycerides is less likely because of possible variation of the regional portal circulation. From a practical point of view it should be emphasized that, in addition to the more frequent hypoechoic pseudolesions, hyperechoic pseudonodular images just anterior to the portal vein can be observed in normal livers; in our experience these lesions should be interpreted as a focal steatosis in an atypical site.