Hepatocellular adenoma: multiphasic CT and histopathologic findings in 25 patients

Benign hepatic tumors and iatrogenic pseudotumors

Myriad benign tumors may be found in the liver; they can be classified according to their cell of origin into tumors of hepatocellular, cholangiocellular, or mesenchymal origin. Common benign hepatic tumors may pose a diagnostic dilemma when they manifest with atypical imaging features. Less frequently encountered benign hepatic tumors such as inflammatory pseudotumor or biliary cystadenoma demonstrate less specific imaging features; however, awareness of their findings is useful in narrowing differential diagnostic considerations. In addition, certain iatrogenically induced abnormalities of the liver may be confused with more ominous findings such as infection or neoplasia. However, knowledge of their common imaging appearances, in addition to the clinical history, is critical in correctly diagnosing and characterizing iatrogenic abnormalities of the liver. Familiarity with both expected and unexpected imaging appearances of common benign hepatic tumors, less commonly encountered benign hepatic tumors, and iatrogenic abnormalities potentially masquerading as hepatic tumors allows the radiologist to achieve an informed differential diagnosis.

Radiological and histopathological manifestations of hepatocellular nodular lesions concomitant with various congenital and acquired hepatic hemodynamic abnormalities

Congenital and acquired hepatic hemodynamic abnormalities are classified into four categories: hepatic arterial inflow disorder, portal vein inflow disorder, hepatic vein outflow disorder, and presence of a third inflow to the liver. Although their detailed etiology is not fully understood, these hepatic hemodynamic abnormalities may cause the formation of hepatocellular nodules. Recent advances in imaging modalities now enable visualization of these hepatocellular nodules concomitantly with the identification of various congenital and acquired hemodynamic abnormalities. Most of these nodular lesions are benign hyperplastic nodules, such as focal nodular hyperplasia, nodular regenerative hyperplasia, and other types of regenerative nodules. However, neoplastic nodules such as hepatic adenoma and hepatocellular carcinoma may also occur in conjunction with hepatic hemodynamic abnormalities. Distinguishing neoplastic nodules, especially malignant liver tumors, from hyperplastic nodules is important. Detection of intranodular Kupffer cells with superparamagnetic iron oxide enhanced magnetic resonance imaging is a key indicator that a nodule is regenerative rather than neoplastic.

Surgical management of hepatocellular adenoma: take it or leave it?

BACKGROUND

Hepatocellular adenoma (HA) is a rare benign tumor of the liver. Surgical resection is generally indicated to reduce risks of hemorrhage and malignant transformation. We sought to evaluate clinical presentation, surgical management, and outcomes of patients with HA at our institution.

METHODS

We performed a retrospective review of 41 patients who underwent surgical resection for HA between 1988 and 2007.

RESULTS

Thirty-eight patients were women, and the median age at presentation was 36 years (range, 19-65 years). The most common clinical presentation was abdominal pain (70%) followed by incidental radiological finding (17%). Twenty-two patients had a history of oral contraceptive use. Median number of HA was one (range, 1-3). There were 32 open cases (3 trisectionectomy, 15 hemihepatectomy, 7 sectionectomy, 4 segmentectomy, and 3 wedge resection), and 9 laparoscopic cases (1 hemihepatectomy, 5 sectionectomy, 1 segmentectomy, and 2 wedge resection). The median estimated blood loss was 225 mL (range, 0-3400 mL). The median length of stay was 6 days (range, 1-15 days). Surgical morbidities included pleural effusion requiring percutaneous drainage (n = 2), pneumonia (n = 1), and wound infection (n = 1). There was no perioperative mortality. Twelve patients had hemorrhage from HA. Hepatocellular carcinoma was observed in two patients with HA. Median follow-up was 23 months (range, 1-194 months), at which time all patients were alive.

CONCLUSION

In view of 29% hemorrhagic and 5% malignant complication rates, we recommend surgical resection over observation if patient comorbidities and anatomic location of HA are favorable. A laparoscopic approach can be safely used in selected cases.

Exophytic benign and malignant hepatic tumors: CT imaging features

Our objective is to describe the CT features of exophytic hepatic tumors those may pose a diagnostic challenge because of the uncertainty of tumor origin. The beak sign and the feeding artery of a tumor are useful diagnostic indicators of exophytic hepatic tumors. Two- or three-dimensional reformation images are also helpful for diagnosis. The CT features of exophytic hepatic tumors are similar to those of the usual intrahepatic tumors except for their location.

Neoplasias hepáticas: caracterização por métodos de imagem

Uma grande variedade de tumores benignos e malignos ocorre no fígado. Embora a caracterização de lesões hepáticas focais possa ser um desafio para o radiologista, a maioria das lesões se apresenta com características de imagem que permitem o seu diagnóstico. O objetivo deste trabalho é o de rever os principais aspectos de imagem dos tumores hepáticos benignos e malignos mais comumente encontrados no fígado adulto.

Focal nodular hyperplasia and hepatic adenoma: differentiation with low-mechanical-index contrast-enhanced sonography

OBJECTIVE

The purpose of our study was to determine the differentiating features of focal nodular hyperplasia (FNH) and hepatic adenoma on contrast-enhanced sonography.

MATERIALS AND METHODS

Sixty-two patients who underwent contrast-enhanced sonography and were confirmed to have FNH (n = 43) or hepatic adenoma (n = 19) were assessed retrospectively for arterial phase enhancement, filling direction, stellate arteries, and portal phase enhancement. An algorithm was applied to these interpreted features to determine the contrast-enhanced sonography diagnosis.

RESULTS

All lesions were hypervascular in the arterial phase. Centrifugal filling was more common in FNH (39 and 32 of 43, 91% and 74% [reader 1 and reader 2]) than in adenoma (3 and 3 of 19, 16%). Centripetal or mixed filling was more common in adenoma (16 and 16 of 19, 84%) than in FNH (4 and 11 of 43, 9% and 26%) (p < 0.001, kappa = 0.61). Stellate arteries characterized FNH (29 and 26 of 43, 67% and 60%) but not adenoma (3 and 2 of 19, 16% and 11%) (p < 0.001, kappa = 0.36). Sustained portal phase enhancement was more common in FNH (37 and 39 of 43, 86% and 91%) than in adenoma (9 and 12 of 19, 47% and 63%) (p < 0.02, kappa = 0.79). The sensitivity, specificity, positive predictive value, and negative predictive value of sonography for diagnosing FNH were 95% and 86%, 74% and 79%, 89% and 90%, and 88% and 71%, (reader 1 and reader 2, respectively).

CONCLUSION

FNH is predicted on the basis of arterial phase centrifugal filling and stellate vascularity on contrast-enhanced sonography. Adenoma is less reliably predicted on the basis of centripetal or mixed filling without stellate vascularity. Sustained portal phase enhancement is more common in FNH than in adenoma but contributes less to the differentiation of these lesions.

Distinguishing benign from malignant liver tumours

Liver masses are very common and most are benign. It is therefore important to avoid unnecessary interventions for benign lesions, while at the same time ensuring accurate diagnosis of hepatic malignancies. Many cancer patients, like the general population, have incidental benign liver lesions. In planning treatment for cancer patients, it is critical to avoid inappropriate treatment decisions based on misdiagnosis of a benign lesion as a metastasis or primary liver malignancy. This article describes the salient imaging features of the common benign liver masses and outlines a general approach to distinguishing between benign and malignant hepatic lesions.

Feasibility of transcatheter arterial chemoembolization for hepatic adenoma

PURPOSE

To assess the efficacy of transcatheter arterial chemoembolization (TACE) for hepatic adenoma (HA).

MATERIALS AND METHODS

Between July 1989 and June 2006, TACE was performed in seven patients with HA (five male and two female patients; mean age, 25 years). The therapeutic results were evaluated by reviewing the clinical records and radiologic studies. The causes of HA were hormonal therapy for aplastic anemia (n = 4) and glycogen storage disease type I (n = 2); in one patient, the cause was unknown. The presenting symptoms were abdominal pain (n = 4) and lower-extremity edema (n = 1). Two patients had no symptoms at presentation. Rupture (n = 1) or impending rupture (n = 3) of the tumors was detected on computed tomographic (CT) scans obtained before TACE. Clinical results were assessed at subsequent TACE sessions and follow-up CT. The mean follow-up duration after the first TACE session was 88 months (range, 16-200 months). The change in tumor size at CT was measured to evaluate the therapeutic results.

RESULTS

The preexisting symptoms were relieved and no procedural-related complications were observed in all patients. Hemostasis and no further bleeding episodes were achieved in patients with rupture or impending rupture with intratumoral hemorrhage. The treatment results were complete remission (n = 2), tumor regression in size by more than 50% (n = 4), and progression (n = 1) at follow-up CT.

CONCLUSION

TACE is a feasible therapeutic modality for HA.

Giant hepatocellular adenoma as cause of severe abdominal pain: a case report

The authors describe the case of a large hepatocellular adenoma diagnosed in a 30-year old woman who came to us complaining of acute pain in the upper abdominal quadrants. The patient had been taking an oral contraceptive pill for the last ten years. We present the clinical features, the diagnostic work-up and the treatment prescribed.

CT and MR imaging evaluation of hepatic adenoma

Hepatic adenoma is a rare benign epithelial tumor that is usually encountered in young women who use oral contraceptives. It is clinically significant because of the risk of hemorrhage and of its low-grade malignancy potential. Adenomas usually are mildly hypervascular at contrast-enhanced CT and MR imaging, and heterogeneous due to the presence of hemorrhage, necrosis, calcifications and fat. The objective of our study was to illustrate the CT and MR imaging findings of hepatic adenoma.

Case-orientated approach to the management of hepatocellular adenoma

Background

Treatment of suspected hepatocellular adenoma (HA) remains controversial. The aim of this study was to evaluate the management of HA at a time when magnetic resonance imaging (MRI) and computed tomography (CT) are highly sensitive methods for diagnosing HA.

Methods

Between January 2000 and January 2005, data from 48 consecutive women with HA (median age 36 years) were prospectively collected. The protocol for diagnostic work-up consisted of multiphasic MRI or CT. Management was observation if the tumour was smaller than 5 cm and surgical intervention if it was 5 cm or larger.

Results

The median follow-up was 24 (range 3–73) months. Sixteen (33 per cent) patients had invasive procedures because of tumour size 5 cm or larger, malignant characteristics or haemorrhage. The remaining 32 patients (67 per cent) were observed; haemorrhage and malignant degeneration did not occur and none of the lesions showed enlargement after withdrawal of oral contraceptives. Multiple HAs were found in 32 (67 per cent) patients; liver steatosis was significantly more common in these patients than in those with a solitary lesion (59 versus 19 per cent; P = 0·008).

Conclusion

Observation of adenomas smaller than 5 cm is justified because of improved radiological reliability. Resection should be reserved for patients with malignant tumour characteristics or with single lesions 5 cm or larger.

Evaluation of nonmalignant liver masses

Nonmalignant liver masses are increasingly being recognized with the widespread use of imaging modalities such as ultrasonography, computed tomography, and magnetic resonance imaging. The majority of these lesions are detected incidentally in asymptomatic patients. Based on the radiologic appearance, benign lesions can be categorized as solid or cystic, single or multiple, hypervascular or hypovascular. Based on histologic characteristics, they are classified as of hepatocellular, biliary, or mesenchymal origin. In the majority of patients, a proper diagnosis can be made based on these characteristics on imaging modalities alone. An invasive approach is seldom required. This review discusses the various characteristics of the most common benign liver lesions and recommends a practical approach.

Hepatocellular adenoma: findings at state-of-the-art magnetic resonance imaging, ultrasound, computed tomography and pathologic analysis

The purpose of this paper is to describe the most recent concepts and pertinent findings of hepatocellular adenomas, including clinical presentation, gross pathology and histology, pathogenesis and transformation into hepatocellular carcinoma (HCC), and imaging findings at ultrasound (US), computed tomography (CT), and magnetic resonance (MR) imaging.

Hepatocellular carcinoma in a liver-cell adenoma within a non-cirrhotic liver

Liver-cell adenomas are benign lesions of the liver occurring predominantly in young women. Hepatocellular carcinomas in most of the cases arise in a cirrhotic liver during the fifth or sixth decade. We describe the case of a 40-year-old woman in whom work-up for epigastric pain revealed a peptic ulcer and a large hepatic mass. Tests for chronic liver diseases were negative. Imaging findings and biopsy specimens of the tumour were inconclusive. The tumour was surgically removed and a hepatocellular carcinoma arising within a liver-cell adenoma in a non-cirrhotic liver was found. Malignant transformation of liver-cell adenoma has only been reported in a few case reports. Mechanisms of transformation remain unclear. The imaging findings as well as histological features are presented in detail and the literature is discussed.

Fat-containing lesions of the liver: radiologic-pathologic correlation

Fat-containing tumors of the liver are a heterogeneous group of tumors with characteristic histologic features, variable biologic profiles, and variable imaging findings. Benign liver lesions that contain fat include focal or geographic fatty change (steatosis), pseudolesions due to postoperative packing material (omentum), adenoma, focal nodular hyperplasia, lipoma, angiomyolipoma, cystic teratoma, hepatic adrenal rest tumor, pseudolipoma of the Glisson capsule, and xanthomatous lesions in Langerhans cell histiocytosis. Malignant liver lesions that can contain fat include hepatocellular carcinoma, primary and metastatic liposarcoma, and hepatic metastases. Identification of fat within a liver lesion can be critical in characterization of the lesion. The imaging characteristics of a lesion coupled with the pattern of intratumoral fatty change are helpful in narrowing the differential diagnosis. Although the presence of fat can be demonstrated with computed tomography or ultrasound, magnetic resonance imaging is the most specific imaging technique for demonstration of both microscopic and macroscopic fat.

Bland embolization of telangiectatic subtype of hepatic focal nodular hyperplasia

Focal nodular hyperplasia (FNH) is a common benign liver tumor that is usually treated conservatively. This report describes a histologic subtype of FNH that is more likely to be symptomatic as a result of hemorrhage and necrosis. The patient in this case was treated initially with surgical resection for multiple focal nodular hyperplasias and subsequently with bland embolization of an unresectable, symptomatic lesion.

Fat in the liver: diagnosis and characterization

The purpose of this article is to provide an update on imaging techniques useful for detection and characterization of fat in the liver. Imaging findings of liver steatosis, both diffuse steatosis and focal fatty change, as well as focal fatty sparing, are presented. In addition, we will review computed tomography (CT) and magnetic resonance (MR) findings of focal liver lesions with fatty metamorphosis, including hepatocellular carcinoma, hepatocellular adenoma, focal nodular hyperplasia, angiomyolipoma, lipoma, and metastases.

Multidetector Row CT of the Liver

CT has always played a major role in the imaging of the liver despite continuous challenge by ultrasound and MR imaging. Introduction of multidetector row CT technology has helped CT to excel in its already established indications and has expanded its capabilities by adding new clinical indications, such as CT angiography or liver perfusion. This article discusses the advantages of multidetector row CT scanners in liver imaging, examines the guidelines to improve image quality by optimizing scanning protocols and contrast administration strategies, and reviews the current and potential clinical applications.

Accurate differentiation of focal nodular hyperplasia from hepatic adenoma at gadobenate dimeglumine-enhanced MR imaging: prospective study

PURPOSE

To prospectively determine the accuracy of differentiating benign focal nodular hyperplasia (FNH) from hepatic adenoma (HA) and liver adenomatosis (LA) by using gadobenate dimeglumine-enhanced magnetic resonance (MR) imaging.

MATERIALS AND METHODS

The ethics committee at each center approved the study, and all patients provided informed consent. Seventy-three patients with confirmed FNH and 35 patients with confirmed HA (n = 27) or LA (n = 8) underwent MR imaging before (T2-weighted half-Fourier rapid acquisition with relaxation enhancement or T2-weighted fast spin-echo and T1-weighted gradient-echo [GRE] sequences) and at 25-30 seconds (arterial phase), 70-90 seconds (portal venous phase), 3-5 minutes (equilibrium phase), and 1-3 hours (delayed phase) after (T1-weighted GRE sequences only, with or without fat suppression) bolus administration of 0.1 mmol per kilogram of body weight gadobenate dimeglumine. The enhancement of 235 lesions (128 FNH, 32 HA, and 75 LA lesions) relative to the normal liver parenchyma was assessed. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and overall accuracy for the differentiation of FNH from HA and LA were determined.

RESULTS

Hyper- and isointensity on T2-weighted and iso- and hypointensity on T1-weighted GRE images were noted for 177 (88.9%) of 199 lesions visible on unenhanced images. On dynamic phase images after contrast material administration, 231 (98.3%) of 235 lesions showed rapid strong enhancement during the arterial phase and appeared hyper- to isointense during portal venous and equilibrium phases. Accurate differentiation of FNH from HA and LA was not possible on the basis of precontrast or dynamic phase images alone. At 1-3 hours after contrast material enhancement, 124 (96.9%) of 128 FNHs appeared hyper- or isointense, while 107 (100%) HA and LA lesions appeared hypointense. The sensitivity, specificity, PPV, NPV, and overall accuracy for the differentiation of FNH from HA and LA were 96.9%, 100%, 100%, 96.4%, and 98.3%, respectively.

CONCLUSION

Accurate differentiation of FNH from HA and LA is achievable on delayed T1-weighted GRE images after administration of gadobenate dimeglumine.

Budd-Chiari-like presentation of hepatic adenoma

Hepatic adenoma is a benign tumor characterized by its hypervascularity. Hepatic adenoma tends to occur more frequently in women and is related to the use of contraceptive hormones, androgenic/anabolic steroids, pregnancy, glycogen storage diseases and hemochromatosis. Hepatic venous obstruction, or Budd-Chiari syndrome, is a condition of hepatic vein occlusion that has many causes. A 35-year-old woman presented shortly after pregnancy with a huge cystic lesion in the liver. The lesion compressed the hepatic vein and created an early stage of Budd-Chiari syndrome. Tumor resection was carried out successfully. The final diagnosis of this case was multiple hepatic adenomas.

Hepatocellular adenoma: imaging findings and pathological correlation

A 45-year-old man presented with a 1-week history of gastrooesophageal reflux, epigastric discomfort and abdominal pain especially in the right hypochondrium. Abdominal ultrasonography, contrast-enhanced spiral computed tomography and magnetic resonance imaging of the abdomen were performed. Eventually, imaging findings were correlated with histopathological analysis, which confirmed the diagnosis of a 18 cm x 16 cm hepatocellular adenoma.

Liver cell adenoma and liver cell adenomatosis

During the last three decades liver cell adenoma and liver cell adenomatosis have emerged as new clinical entities in hepato-logical practice due to the widespread use of oral contraceptives and increased imaging of the liver. On review of published series there is evidence that 10% of liver cell adenomas progress to hepatocellular carcinoma, diagnosis is best made by open or laparoscopic excision biopsy, and the preferred treatment modality is resection of the liver cell adenoma to prevent bleeding and malignant transformation. In liver cell adenomatosis, the association with oral contraceptive use is not as high as in solitary liver cell adenomas. The risk of malignant transformation is not increased compared with solitary liver cell adenomas. Treatment consists of close monitoring and imaging, resection of superficially located, large (>4 cm) or growing liver cell adenomas. Liver transplantation is the last resort in case of substantive concern about malignant transformation or for large, painful adenomas in liver cell adenomatosis after treatment attempts by liver resection.

Differentiating a chronic hyperplastic mass from pancreatic cancer: a challenge remaining in multidetector CT of the pancreas

A multitude of clinical symptoms originate from pancreatic inflammatory or neoplastic processes due to their highly complex composition, function, and anatomic relationships to adjacent organs as well as the heterogeneous patterns of vascular perfusion and neural innervation of the pancreatic gland which complicate an early and precise diagnosis. Whereas early assessment of inflammatory or neoplastic pancreatic processes is a prerequisite for a successful curative approach, the classical radiologic signs of chronic pancreatitis and pancreatic carcinoma show significant similarities. This article provides an overview of the pathogenesis and imaging findings in chronic pancreatitis and pancreatic cancer, including some new approaches for visualizing the subtle but distinct differences between these two entities.

Contemporary management of benign liver tumors

Benign lesions of the liver represent diagnostic dilemmas, clinically and radiographically; however, certain clues can help the extensive differential diagnosis of both benign and malignant processes. Hemangiomas and simple cysts have very distinct and very specific radiographic characteristics, and if diagnosed, no further work-up is necessary. The remaining benign lesions have significant overlap, even though there are some more common characteristics to each of the entities. Still, differentiation of any particular lesion outside simple cysts or hemangioma may be difficult. It is reasonable and relatively simple, with minimal invasiveness, to perform US- or CT-guided, percutaneous core-needle biopsies. It is recommended that core biopsies be performed, because many of the benign entities have some overlapping histologic features, and if fine-needle aspirations are performed, a definitive diagnosis may be difficult to obtain. A definitive pathological diagnosis still cannot be made in some cases, even after needle biopsy. Therefore, a surgical resection or wedge resection may be necessary if a benign process cannot be definitively ruled out.

Spontaneous intraperitoneal hemorrhage: imaging features

Spontaneous intraperitoneal bleeding can result from a vast array of etiologies. Fortunately, most are uncommon and currently available imaging modalities can be used to differentiate them in almost all cases. Meticulous imaging technique and careful observation of key imaging features are important for accurate characterization of the organ of origin of the spontaneous bleeding. CT is the single most important imaging technique in the detection and characterization of spontaneous intraperitoneal bleeding. Further development in multidetector technology, such as the introduction of new machines with 8 or 16 detectors, should improve the effectiveness of CT further. Sonography and MR imaging are complimentary to CT, especially in patients with pelvic abnormalities or equivocal CT findings.

Hepatic adenomas in male patients

BACKGROUND

Hepatic adenomas are benign tumours of the liver most commonly seen in premenopausal women. However, it is now clear that adenomas may occur in males. This small series reviews the characteristics of hepatic adenomas in males.

CASE OUTLINES

Three cases of solitary hepatic adenoma occurring in otherwise well male patients (age 22-48 years) are presented. Two patients presented with abnormal liver function tests while one presented with abdominal pain. Imaging of the lesions demonstrated typical appearances of hepatocellular adenoma, resection was undertaken in all cases and all patients remain alive and well.

DISCUSSION

Up to 20% of adenomas are documented as occurring in male patients. Most are solitary and occur in patients without recognised risk factors (steroid therapy and glycogen storage diseases types I and III). However, multiple adenomas are most commonly seen in male patients with risk factors. The imaging characteristics and presentation of adenomas in males are similar to female patients and, most importantly, intraperitoneal rupture and malignant transformation are documented in untreated adenomas in males.

Telangiectatic focal nodular hyperplasia: US, CT, and MR imaging findings with histopathologic correlation in 13 cases

PURPOSE

To review the ultrasonographic (US), computed tomographic (CT), and magnetic resonance (MR) imaging findings in 13 patients with telangiectatic focal nodular hyperplasia (FNH) and to compare imaging features with histopathologic results from resected specimens.

MATERIALS AND METHODS

US, helical multiphasic CT, and MR images in 13 patients with pathologically proven telangiectatic FNH were reviewed retrospectively. Two abdominal radiologists evaluated lesions for number, size, heterogeneity, surface characteristics, presence of a central scar, presence of a pseudocapsule, US appearance, attenuation at CT, signal intensity at MR imaging, and presence of associated lesions. Imaging and pathologic findings were compared.

RESULTS

Sixty-one lesions (5-140 mm in diameter) were seen at imaging. Lesions were multiple in eight of 13 (62%) patients. Imaging characteristics were heterogeneity in 26 of 61 lesions (43%), well-defined margins in 43 of 61 (70%), lack of a central scar in 56 of 61 (92%), presence of a pseudocapsule in three of 61 (5%), hyperintensity on T1-weighted MR images in 17 of 32 (53%), strong hyperintensity on T2-weighted MR images in 24 of 54 (44%), and persistent enhancement on delayed contrast material-enhanced CT or T1-weighted MR images in 23 of 38 (61%). No specific US pattern was noted. Two patients had additional lesions: One had classic FNH, and the other had a cavernous hemangioma. Hyperintensity on T1-weighted MR images was due to sinusoidal dilatation. Hyperintensity on T2-weighted MR images correlated well with the presence of inflammation.

CONCLUSION

Telangiectatic FNH differs from typical FNH at imaging: Atypical FNH features often observed with telangiectatic FNH are lack of a central scar, lesion heterogeneity, hyperintensity on T1-weighted MR images, strong hyperintensity on T2-weighted MR images, and persistent contrast enhancement on delayed contrast-enhanced CT or T1-weighted MR images.

FNH-like nodules: Possible precursor lesions in patients with focal nodular hyperplasia (FNH)

BACKGROUND: The typical lesion of focal nodular hyperplasia (FNH) is a benign tumor-like mass characterized by hepatocytic nodules separated by fibrous bands. The solitary central artery with high flow and the absent portal vein give the lesions their characteristic radiological appearance. The great majority of cases seen in daily practice conform to the above description. Additional small nodules (from 1-2 up to 15-20 mm in diameter) detected by imaging techniques or on macroscopic examination may be difficult to identify as representing FNH if they lack the key features of FNH as defined in larger lesions. The aim of this study was to characterize these small nodules, and to compare their characteristics with those of typical lesions of FNH present in the same specimens. RESULTS: Eight patients underwent hepatic resections for the removal of a mass lesion ("nodule") diagnosed as: FNH (1 patient); nodules of unknown nature (5 patients); or nodules thought to be adenoma or hepatocellular carcinoma (2 patients). Six nodules out of 9 discovered by imaging techniques met histopathological criteria for the diagnosis of typical FNH, at least in parts of the nodule; 2 nodules corresponded to a minor form of FNH ("subtle FNH") and one nodule to a steatotic area. Although FNH was thought to be found in a normal or nearly normal liver, this study revealed that, in addition, there were various types of small FNH-like nodules and vascular abnormalities in the liver with typical FNH nodule. The various types of small FNH-like nodules (n = 8, diameter 2 to 20 mm) consisted of the association to various degrees of numerous and/or enlarged arteries in portal tracts or in septa, with hyperplastic foci, slight ductular reaction, and regions of sinusoidal dilatation, accompanied by thin fibrous bands. Vascular abnormalities consisted of unpaired arteries, portal tracts with arteries larger than the associated bile duct, and regions of sinusoidal dilatation. CONCLUSIONS: Although these small nodules can be considered as insufficient type or abortive forms of FNH, or adenoma, they can be precursors of the large mass lesions in which FNH was recognized and defined.

Association of adenoma and focal nodular hyperplasia: experience of a single French academic center

BACKGROUND: We report our experience of the simultaneous occurrence of adenoma and focal nodular hyperplasia (FNH). Liver cell adenoma together with FNH was found in five out of 30 cases of "multiple benign hepatocytic nodules" collected in our files of the Department of Pathology of the University Hospital of Bordeaux, during the last 12 years. All five cases were women on oral contraceptives. In all cases, the reason for surgery was the discovery, by imaging techniques, of an adenoma (4 cases) or of an unidentified benign tumor, possibly an adenoma. RESULTS: Four cases of FNH were discovered by imaging techniques, prior to surgery. Additional small nodules were diagnosed either during surgery or during the slicing of the specimen in 3 cases. Adenoma and the FNH cases identified by imaging techniques were confirmed as such by light microscopy. Some small nodules could not be categorized with certainty because they contained biliary structures without ductular reaction. In one case, the non-nodular liver was abnormal around the area in which there were multiple nodules: there was approximation of portal tracts with portal and hepatic venous thromboses, and portal tract remnants with arteries surrounded with a rim of fibrosis. In two cases, some large hepatic veins had thickened walls. CONCLUSIONS: The association of FNH and adenoma could be coincidental or secondary to shared causal mechanisms: a) systemic and local angiogenic abnormalities induced by oral contraceptives; b) tumor-induced growth factors; c) thrombosis and local arterio-venous shunting. A better recognition of the association of adenoma and FNH, particularly in the context of multiple nodules, could be useful in clinical practice.

Computed tomography and magnetic resonance imaging evaluation of liver cancer

Focal liver lesions occur commonly and with varying histology, each requiring radically different management. There are a multitude of imaging modalities currently being used for detecting and characterizing focal liver neoplasms. The primary modalities include ultrasonography, computed tomography (CT), magnetic resonance imaging (MRI), and rarely, angiography. CT and MRI have benefited from rapid technologic advances, and MRI, in particular, from the advent of new contrast agents.

Hepatic neoplasms: computed tomography and magnetic resonance features

Over the last decade, major advances in computed tomography and magnetic resonance technology have occurred. These advances enable accurate, noninvasive detection and characterization of many hepatic neoplasms. This article illustrates the role of imaging in the evaluation of hepatic neoplasms and reviews the typical imaging features of both benign and malignant hepatic tumors. Benign tumors discussed include hemangiomas, focal nodular hyperplasia, hepatocellular adenoma, and simple cysts, as well as cysts associated with polycystic liver disease. Malignant neoplasms reviewed include metastases and conventional hepatocellular carcinoma as well as less common tumors such as fibrolamellar hepatocellular carcinoma, intrahepatic cholangiocarcinoma, angiosarcoma, and epithelioid hemangioendothelioma.

Benign liver neoplasms

A variety of benign focal liver lesions are easily characterized with currently available imaging techniques and contrast agents. The most common benign liver lesions, such as hemangioma, bile duct cyst, and FNH, reveal characteristic cross-sectional imaging features that allow an accurate diagnosis. For atypical variants and more uncommon lesions, including HCA, angiomyelioma, infantile hemagioendothelioma, and mesenchymal hamartoma, integration of clinical data can often help in the interpretation of imaging studies. Finally, for the remaining lesions, such as hepatic adenomatosis, the imaging findings may not be specific enough to negate the need for a tissue biopsy.

Hepatocellular carcinoma in noncirrhotic liver: CT, clinical, and pathologic findings in 39 U.S. residents

PURPOSE

To review clinical, pathologic, and computed tomographic (CT) findings in patients with hepatocellular carcinoma (HCC) in noncirrhotic liver.

MATERIALS AND METHODS

Clinical, pathologic, and imaging findings were retrospectively evaluated in 39 patients with HCC in noncirrhotic liver. Helical multiphasic CT scans obtained with 125 mL of contrast medium at a rate of 4 or 5 mL/sec were reviewed for morphologic features such as tumor size, margins, and hemorrhage and degree of enhancement.

RESULTS

All patients (25 men, 14 women; mean age, 61 years) were U.S. residents; none had an Asian surname. Twenty-four patients (62%) had no identifiable risk factors; 34 (87%) were symptomatic. HCC was proved and cirrhosis excluded with biopsy in all cases. HCC was moderately (n = 32) or well (n = 6) differentiated in 97% of cases and poorly differentiated in one. Serum alpha-fetoprotein level was elevated in 26 patients. Large tumors (mean diameter, 12.4 cm) were depicted at CT in all cases. Thirty-two patients had a solitary or dominant mass. At CT, tumor margins were well defined in 21 patients, with a lobulated surface in 33. Calcifications were depicted in 11, hemorrhage in 10, fat in four, dilated intrahepatic bile ducts in 17, and abdominal lymphadenopathy in eight. In 38 patients, tumors were heterogeneous with areas of necrosis. HCC was hypoattenuating on nonenhanced images in 34, heterogeneously hyperattenuating at arterial phase in 38, and hypoattenuating at portal phase in 35 patients.

CONCLUSION

HCC developed in the absence of cirrhosis or known risk factors and typically appeared as a large symptomatic hepatic tumor with clinical, laboratory, and CT features that distinguish it from most other hepatic masses.

Hepatic adenomas: imaging and pathologic findings

Hepatocellular adenoma is a rare benign lesion that is most often seen in young women with a history of oral contraceptive use. It is typically solitary, although multiple lesions have been reported, particularly in patients with glycogen storage disease and liver adenomatosis. Because of the risk of hemorrhage and malignant transformation, hepatocellular adenomas must be identified and treated promptly. At pathologic analysis, hepatocellular adenoma is usually a well-circumscribed, nonlobulated lesion, and at gross examination, resected adenomas frequently demonstrate areas of hemorrhage and infarction. Most adenomas are not specifically diagnosed at ultrasonography (US) and are usually further evaluated with computed tomography (CT) or other imaging modalities. Color Doppler US may help differentiate hepatocellular adenoma from focal nodular hyperplasia. Multiphasic helical CT allows more accurate detection and characterization of focal hepatic lesions. Hepatocellular adenomas are typically bright on T1-weighted magnetic resonance images and predominantly hyperintense relative to liver on T2-weighted images. The prognosis of hepatic adenoma is not well established. Criteria that guide treatment include the number and size of the lesions, the presence of symptoms, and the surgical risk incurred by the patient. Understanding the imaging appearance of hepatocellular adenoma can help avoid misdiagnosis and facilitate prompt, effective treatment.

Focal nodular hyperplasia: CT findings with emphasis on multiphasic helical CT in 78 patients

PURPOSE

To evaluate features of focal nodular hyperplasia (FNH) at multiphasic helical computed tomography (CT).

MATERIALS AND METHODS

Clinical, pathologic, and preoperative imaging findings were retrospectively reviewed in 78 patients. Conventional liver CT was performed in nine patients; helical multiphasic CT, in 69. Diagnosis was based on complete resection (n = 20), biopsy (n = 42), or clinical and imaging follow-up for a minimum of 6 months (n = 16). Number, size, location, margins, surface, homogeneity of enhancement, and presence of a central scar, mass effect, exophytic growth, calcification, pseudocapsule, or vessels feeding or draining the lesion were evaluated.

RESULTS

CT depicted 124 tumors (mean diameter, 4.1 cm; range, 1-11 cm); 62 were small (< or =3 cm). FNHs were hypervascular and hyperattenuating to liver on 106 of 106 arterial phase scans and were isoattenuating to liver on 82 of 89 delayed scans. Of the 124 tumors, 111 enhanced homogeneously, 109 had a smooth surface, 101 were subcapsular, 89 had ill-defined margins, and 62 had a central scar that was observed more often in large lesions (40 of 62 lesions) than in small lesions (22 of 62 lesions). FNHs less frequently exerted a mass effect (43 lesions), had vessels around or within the lesion (42 lesions), demonstrated exophytic growth (40 lesions), or showed a pseudocapsule (10 lesions). Only one FNH had calcification.

CONCLUSION

Helical CT demonstrates characteristic features that may allow confident diagnosis of FNH. In typical cases, neither biopsy nor further imaging is necessary.

Liver adenomatosis: clinical, histopathologic, and imaging findings in 15 patients

PURPOSE

To report and correlate the clinical, histopathologic, and imaging findings in 15 patients with liver adenomatosis.

MATERIALS AND METHODS

Fifteen adult patients had more than 10 hepatic adenomas each and no history of glycogen storage disease or anabolic steroid use. Ten of them underwent bolus-enhanced dynamic computed tomography (CT) with or without magnetic resonance (MR) imaging, ultrasonography, and/or angiography.

RESULTS

Clinical abnormalities included abdominal pain in 11 (73%) and hepatomegaly in 10 (67%) patients, and abnormal liver function in 10 (91%) of 11 patients. The number of adenomas in each patient was 10-50 at imaging, but many more lesions were found in the resected specimens. Hemorrhage was commonly found within adenomas at histopathologic analysis, but only four patients had clinical and imaging evidence of substantial hemorrhage. In all patients, the adenomas increased over time, and two patients developed hepatocellular carcinoma. CT and MR features of the adenomas included evidence of hypervascularity (63%), intratumoral fat (50% of patients at CT, 80% at MR), and decreased conspicuity at portal venous and delayed-phase imaging. Fifty percent of patients had congenital or acquired hepatic vascular abnormalities.

CONCLUSION

The imaging and histopathologic features of individual adenomatous lesions are similar to those reported in young women who are taking oral contraceptives. However, the lesions in liver adenomatosis are not steroid dependent but rather multiple, progressive, and symptomatic, and they are more likely to lead to impaired liver function, hemorrhage, and perhaps malignant degeneration.