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1、Outline,FNH accounts for approximately 8%of all primary hepatic tumor and is the second most common benign liver tumor after hemangioma.This benign tumour occurs most commonly in women aged 2050 years,but may occur in both men and women at any age,with multiple lesions being found in 20 per cent of
2、cases.,FNH,Oral contraceptive口服避孕药 use is associated with FNH but the responsibility of oral contraceptives in the occurrence of the lesion has not been demonstrated.,Clinical symptoms,FNH is usually an incidental finding at imaging and only one-third are discovered because of clinical symptoms such
3、 as mild epigastric pain or discomfort and or palpable abdominal mass.Blood liver tests are normal in half of the cases and show only increased in serum gamma-glutamyl-transpeptidase血清r-谷氨酰转肽酶 activity in most of the remnants.,well-circumscribed lobulated mass with central scar(arrow)and radiating s
4、eptations.,Pathological appearance,FNH is defined as a nodule composed of benign-appearing hepatocytes occurring in a liver that is otherwise histologically normal.FNH is a hyperplastic liver parenchyma（增生性肝实质）subdivided into nodules by fibrous septa that may form stellate scars（星状瘢痕）.The lesion is
5、usually solitary(80%)and measures less than 5 cm in diameter.Occasionally,FNH is pedunculated(蒂).,Photomicrograph of histopathologic specimen shows regions of nodular hepatocellular proliferation separated by radiating bands and surrounding myxomatous scar(arrows).,The margin is sharp,often lobulate
6、d and no capsule is present.Hemorrhage and necrosis are rare.At microscopy,the central fibrotic zone is dense connective tissue（致密结缔组织）which contains numerous abnormally thickwalled arteries.Marked proliferation of biliary structures surrounded by inflammatory cells is observed within and at the per
7、iphery（边缘）of the fibrous septae.Kupffer cells are also seen within the lesion.,FNH,classic(80%)non-classic(20%),(a)telangiectatic FNH,(b)with atypia,(c)mixed hyperplastic and adenomatous FNH,Diagnosis（CT）,Nonenhanced CT scans,FNH is demonstrated as a focal hypodense or isodense mass compared with no
8、rmal liver.A central hypodense scar is depicted in only one-third of the cases.Calcifications within the central scar are very rare and observed in only about 1%of the cases.,contrast-enhanced CT scan,arterial phase,The lesion enhances rapidly in most cases and the lesion to liver contrast is high.L
9、esion contour is well demarcated and may be lobulated.At that time,the central scar is hypodense and appears more evident than on unenhanced CT scans.,portal venous phase,lesion enhancement decreases and the lesion may be either iso or slightly hyperdense relative to normal liver.Small-sized FNH may
10、 be barely visible,whereas large-sized FNH are visualized due to deformity in the liver contour or displacement of adjacent vessels or depiction of a relatively hypoattenuating central scar.,delayed phase,FNH are isodense relative to normal liver and in most cases,central scars appear iso or hyperat
11、tenuating.A central scar is observed more often in large lesions than in small lesions.,CT,T1 WI T2WI,Diagnosis（MRI）,Nonenhanced MRI scans,Typical FNHs are iso or hypointense on T1WI and iso or slightly hyperintense on T2WI.The central scar is hypointense on T1WI and strongly hyperintense on T2WI.,c
12、ontrast-enhanced MRI scan,dramatic enhancement in the arterial phase,followed by isointensity of the lesion during the portal venous phase.On delayed phase imaging,the central scar shows high signal intensity.,Atypical forms,scars are seen in more than 80%of cases.However,radio-pathologic papers hav
13、e demonstrated that some FNH may have no scar even at pathology especially FNH measuring less than 3 cm in diameter。,Rarely,scars remain hypodense or isodense on delayed scans or are hypointense on T2-weighted images.These findings may be observed up to 20%of cases.Nearly all FNHs are hypervascular
14、at the arterial phase of the enhancement,but lesion enhancement may vary at the portal phase or on delayed images.Both hypodensity or intensity of the mass on delayed phase,or on both portal vein and delayed phase images as well as hyperdensity-intensity of the mass on the portal vein phase or on bo
15、th portal vein and delayed phases may be seen.,Although FNH is a non-encapsulated lesion,capsule like enhancement may be observed on portal vein and on delayed phase scans in about 2536%of the cases.The pseudocapsule(假包膜)is hypointense on T1 and slightly hyperintense on T2.,Differential diagnosis,肝囊
16、肿Hepatic cyst,原发性肝癌primary hepatic carcinoma,肝囊肿Hepatic cyst,noncontrast-enhanced,contrast-enhanced,CT,nonenhancement,肝囊肿Hepatic cyst,MRI,contrast-enhanced,nonenhancement,原发性肝癌primary hepatic carcinoma,快进快出,noncontrast-enhanced,contrast-enhanced,CT,原发性肝癌primary hepaticcarcinoma,快进快出,contrast-enhanced,Thank you.,
