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1、肝局灶性结节性增生肝局灶性结节性增生Focal nodular hyperplasia (FNH) 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
2、, with multiple lesions being found in 20 per cent of cases.FNH Oral contraceptive口服避孕药口服避孕药 use is associated with FNH but the responsibility of oral contraceptives in the occurrence of the lesion has not been demonstrated. Clinical symptomsFNH is usually an incidental finding at imaging and only o
3、ne-third are discovered because of clinical symptoms such 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-circumscr
4、ibed lobulated mass with central scar (arrow) and radiating septations. Pathological appearanceFNH 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（增生性肝实质）subdivided into nodules
5、 by fibrous septa that may form stellate scars（星状瘢痕）（星状瘢痕）.The lesion is usually solitary (80%) and measures less than 5 cm in diameter . Occasionally, FNH is pedunculated(蒂蒂). Photomicrograph of histopathologic specimen shows regions of nodular hepatocellular proliferation separated by radiating ba
6、nds and surrounding myxomatous scar (arrows).The margin is sharp, often lobulated 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
7、 biliary structures surrounded by inflammatory cells is observed within and at the periphery（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）Non
8、enhanced CT scans FNH is demonstrated as a focal hypodense or isodense mass compared with normal 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 scanarte
9、rial phaseThe lesion enhances rapidly in most cases and the lesion to liver contrast is high . Lesion 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 phaselesion enhancement decreases an
10、d the lesion may be either iso or slightly hyperdense relative to normal liver. Small-sized FNH may 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 p
11、hase FNH are isodense relative to normal liver and in most cases, central scars appear iso or hyperattenuating . A central scar is observed more often in large lesions than in small lesions .CTT1 WI T2WI Diagnosis（MRI）Nonenhanced MRI scans Typical FNHs are iso or hypointense on T1WI and iso or sligh
12、tly hyperintense on T2WI. The central scar is hypointense on T1WI and strongly hyperintense on T2WI.contrast-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 sign
13、al intensity. Atypical formsscars are seen in more than 80% of cases . However, radio-pathologic papers have 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 hypointen
14、se on T2-weighted images. These findings may be observed up to 20% of cases . Nearly all FNHs are hypervascular 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 p
15、ortal vein and delayed phase images as well as hyperdensity-intensity of the mass on the portal vein phase or on both 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 25
16、36% of the cases . The pseudocapsule(假包膜) is hypointense on T1 and slightly hyperintense on T2. Differential diagnosisv肝囊肿肝囊肿Hepatic cystv 原发性肝癌原发性肝癌primary hepatic carcinomav肝囊肿肝囊肿Hepatic cystnoncontrast-enhancedcontrast-enhancedCTnonenhancementv肝囊肿肝囊肿Hepatic cystT1WIT2WIMRIcontrast-enhancednonenhancementv 原发性肝癌原发性肝癌primary hepatic carcinoma快进快出快进快出noncontrast-enhancedcontrast-enhancedCTv 原发性肝癌原发性肝癌primary hepaticcarcinoma快进快出快进快出T1WIT2WIcontrast-enhancedThank you.
