Atypical CT and MRI Features of Focal Nodular Hyperplasia of Liver: A Study with Radiologic-Pathologic Correlation

Abstract

Focal Nodular Hyperplasia (FNH) is the second most hepatic tumor next to hemangioma predominantly affecting women. It is a benign regenerative nodule having an unencapsulated well-defined mass with fibrovascular septae and proliferating bile ductules. Gadoxetic acid is a hepatocyte specific MR contrast agent which is known to be specific for the identifying FNH. Congenital vascular malformation and enlargement due to hormone stimulation is being considered as the main cause of FNH. The central stellate fibrovascular scar is a typical diagnostic imaging feature of FNH and the atypical pathological findings of FNH include large lesions multiple in number, internal necrosis, haemorrhagic foci and fatty infiltration. The atypical imaging features include nonenhancement of the central scar, calcification of the lesion, nonvisualized central scar and pseudocapsular enhancement on delayed imaging. For the accurate diagnosis of FNH, study of atypical radiologic features of FNH in correlation with pathological findings is the most essential. The macroscopic and the microscopic pathognomic changes should be taken as helpful points in the diagnosis of FNH. The main objective of this study is to recognize and understand the typical and atypical imaging patterns observed in CT and MR imaging of FNH with pathological correlation which avoids the necessity of biopsy and further investigations.

A unique presentation of peliosis hepatis: A case report and comprehensive review of the literature

“…Magnetic resonance imaging (MRI) was a commonly utilized imaging modality (40.0%; n=25) with MRI T1-weighted images appearing hypointense with an enhancement that progresses centrifugally; cavities display a rim of enhancement with hematoma [17,18,26,35]. T2-weighted MRI images appear hyperintense to the parenchyma with multiple foci of high signal, consistent with what was seen in our patient using Gadolinium contrast enhancement (Figure 3) [16][17][18]26].…”

“…A majority of asymptomatic patients (22%; n=14; Table 1) were diagnosed incidentally by imaging (71%; n=10), with variable findings within lesional tissue and the concomitant presence of hepatic steatosis [9,16,17,26,32]. Vascular tumors, hepatic adenomas, hepatocellular carcinoma, hepatic abscesses and other cystic liver diseases remained in the differential [4,6,12,13,18,27], with normal magnetic resonance pancreatography (MRCP) (6.3%; n=4) and fluorodeoxyglucose-positron emission tomography (FDG-PET) (11.1%; n=7) ruling out malignant processes [1,4,12].…”

“…Doppler studies can identify blood flow and thrombi or portal obstruction [6,16,26]. Contrast-enhanced CT (54.0%; n=34), the preferred imaging modality [4,16,18,26,[32][33][34], differentiates hypoattenuating peliotic lesions versus normal parenchyma [16,18,[32][33][34][35]; characteristically, early central enhancement during the arterial phase with centrally accumulating contrast in a "target sign" that diffuses to the periphery during the venous phase is noted in PH [16,18,26,[33][34][35]. With an active hemorrhage, hyperattenuating contrast material may accumulate or leak during the late phase [4,16,18,26,[32][33][34].…”

“…Magnetic resonance imaging (MRI) was a commonly utilized imaging modality (40.0%; n=25) with MRI T1-weighted images appearing hypointense with an enhancement that progresses centrifugally; cavities display a rim of enhancement with hematoma [17,18,26,35]. T2-weighted MRI images appear hyperintense to the parenchyma with multiple foci of high signal, consistent with what was seen in our patient using Gadolinium contrast enhancement (Figure 3) [16][17][18]26]. Diagnostic angiography identifies contrast accumulation during the late arterial phase and persistent enhancement during the venous phase with multiple vascular nodules [4,6,8,20,36]; angiography also allows embolization to commence [36][37][38].…”

“…Risk factors include chronic immunosuppression, anabolic steroid use, oral contraceptive (OCP) use, HIV/AIDS, and infection with Bartonella spp [2,4,[7][8][9][10][11][12][13]. Most cases are discovered incidentally on imaging or during routine follow-ups for abnormal lab results [2,9,[14][15][16][17][18]. Peliosis hepatis lesions may spontaneously or surgically rupture and hemorrhage, which is associated with significant mortality [4,8,[19][20][21][22].…”