AJR:179, September 2002 759 Original Report OBJECTIVE. The records of 10 patients with focal nodular hyperplasia inducing intrahe- patic vein obstruction were reviewed. The purpose of this study was to describe and empha- size the imaging features of these findings. CONCLUSION. Focal nodular hyperplasia may be responsible for hepatic vein obstruc- tion with hepatic vein collaterals. The relatively large size and central location of the lesions seem to play important roles in the obstruction of the hepatic veins. ocal nodular hyperplasia is the sec- ond most common benign liver le- sion after hemangioma and accounts for 8% of all primary hepatic tumors [1, 2]. It typically affects women of childbearing age. The exact pathogenesis of focal nodular hyperplasia is not known, but it seems to be the result of a hyperplastic, rather than a neoplastic, process. Vascular malformation or injury has been sug- gested as the triggering mechanism of hepato- cellular hyperplasia [1, 3, 4]. Focal nodular hyperplasia is classically described as a nodular, hypervascular homogenous lesion with a central stellate scar containing malformed vascular structures with radiating fibrous septa [1]. The only radiologic finding may be a subtle mass ef- fect with compression of adjacent structures, which has been previously described in large fo- cal nodular hyperplasia [2]. However, vascular compression, especially hepatic vein obstruc- tion, remains rare; to our knowledge, only one case has been reported in the literature [5]. We describe the clinical findings of 10 patients with focal nodular hyperplasia resulting in hepatic vein obstruction and compare all findings with those of a series of 64 patients with focal nodular hyperplasia seen during the same period. Materials and Methods Patients We retrospectively reviewed the records of 74 patients with focal nodular hyperplasia from 1995 to 2000. All patients were women between 18 and 70 years old (mean age, 38 years). We classified the records into a control group (n = 64) and a group having focal nodular hyperplasia with he- patic vein obstruction (compressive group) (n = 10). All patients had undergone sonography, CT, or contrast-enhanced MR imaging of the liver, or all three examinations. Helical CT was performed in all patients with a triphasic dynamic exploration during the arterial, portal, and delayed phases after injection of iodine contrast medium. All MR im- aging included fast T2-weighted sequences and T1-weighted dynamic gradient-echo sequences af- ter IV injection of gadopentetate dimeglumine. Image Interpretation Two radiologists reviewed all images from the two groups in consensus. Diagnosis of focal nodu- lar hyperplasia was made in the presence of a typi- cal appearance on CT or MR imaging and by histologic sampling in atypical cases. A lesion was considered to have typical appear- ance if it was homogeneous, was unencapsulated, and showed regular or lobulated margins on sonog- raphy, CT, or MR imaging. On CT, a typical lesion was slightly hypoattenuating or isoattenuating and enhanced on the arterial phase after injection of contrast medium, except for a central hypoattenuat- ing scar that later enhanced [6, 7]. On MR imaging, a typical lesion was isointense or nearly isointense on T1- and T2-weighted imaging and showed a central scar that enhanced on delayed gadolinium- enhanced T1- weighted sequences [2]. The number, size, and location of the lesions were assessed. Focal nodular hyperplasia was clas- Anne-Sophie Rangheard 1 Valérie Vilgrain 1 Pascale Audet 1 Dermot O’Toole 2 Marie-Pierre Vullierme 1 Dominique Valla 3 Jacques Belghiti 4 Yves Menu 1 Received June 11, 2001; accepted after revision February 26, 2002. 1 Department of Radiology, Hospital Beaujon, 100 ave. du Général Leclerc, 92110 Clichy, France. Address correspondence to A.-S. Rangheard. 2 Department of Gastro-Enterology, Hospital Beaujon, 92110 Clichy, France. 3 Department of Hepatology, Hospital Beaujon, 92110 Clichy, France. 4 Department of Visceral Surgery, Hospital Beaujon, 92110 Clichy, France. AJR 2002;179:759–762 0361–803X/02/1793–759 © American Roentgen Ray Society F Focal Nodular Hyperplasia Inducing Hepatic Vein Obstruction Downloaded from www.ajronline.org by 52.73.204.196 on 05/18/22 from IP address 52.73.204.196. Copyright ARRS. For personal use only; all rights reserved