A Case of Postoperative Recurrence of Fibrolamellar Hepatocellular Carcinoma with Increased Vitamin B12 Binding Capacity in a Young Japanese Female

Exploring the molecular pathogenesis, diagnosis and treatment of fibrolamellar hepatocellular carcinoma: A state of art review of the current literature

This paper aims to present a detailed overview of fibrolamellar carcinoma (FLC), a variant of hepatocellular carcinoma (HCC) that accounts for approximately 1-9% of all cases a. according to the SEER database. Despite ongoing research, the aetiology of FLC tumours remains unclear. Nevertheless, FLC is believed to have a better overall prognosis than other primary liver tumours, such as hepatocellular carcinoma (HCC) and intrahepatic cholangiocarcinoma. This study aims to present a comprehensive overview of fibrolamellar carcinoma (FLC), with a focus on its epidemiology, pathogenesis, diagnosis, treatment, and prognosis. FLC frequently incorporate features of stomach pain, weight loss, and malaise in their clinical signs and symptoms, which are generally nonspecific Ultimately, the most common physical finding is an abdominal mass or hepatomegaly. With this said, several unusual presentations have been documented such as Budd Chiari syndrome, severe anaemia, non-bacterial thrombotic endocarditis and many more. In regards to this tumour's genetic analysis, it is characterised by a 400 kb deletion on chromosome 19 leading to a functional DNAJB1-PRKACA chimeric transcript in addition to tetraploidy in 50% of cases. FLC is chromosomally stable as compared to typical HCC. mTOR pathway activation has also been found to play a critical role in 47% of these tumours and EFGR over-expression is also evident. Fibrolamellar carcinomas (FLCs) exhibit a distinctive gross appearance, characterized by a yellow to pale tan colour, with a consistency that can vary from soft to firm and hard. In addition, a central scar is observed in 60-70% of FLC cases. The central scar is typically white or grey in colour and has a fibrous appearance, which is often surrounded by nodular, tumour-like tissue. Its histologic appearance is characterized by large polygonal cells with abundant eosinophilic cytoplasm, large vesiculated nuclei, large nucleoli, and arranged in lamellar bands of collagen fibres. Lamellar bands of fibrosis, consisting of collagen type I, III and IV, have also been identified as a distinctive histologic feature that is observed under low power magnification. Ultrasound, CT and MRI along with image guided biopsy are the primary modalities in diagnosis. Current management options include systemic therapy which has thus far been unremarkable with platinum-based therapies as well combination therapy with interferon alpha-2b being the most successful options. Surgical resection remains the primary treatment modality and there have been no advances in targeted therapies. Although the prognosis for FLC is favourable as compared to other hepatic cancer subtypes such as intrahepatic cholangiocarcinoma, there is a high rate of recurrence ranging from 33% to 100% with a median recurrence-free survival of 20-48 months. As a result of this there is a low overall cure rate associated with this tumour type and much more research is required to gain an in-depth understanding of the molecular mechanisms occurring in order to provide more adequate treatment to patients who suffer from this condition.

The prognosis of fibrolamellar carcinoma versus conventional hepatocellular carcinoma: a study based on propensity score matching

BACKGROUND

The prognosis of fibrolamellar carcinoma (FLC) versus conventional hepatocellular carcinoma (HCC) remains controversial. Thus, this study aimed to compare the prognosis of FLC and HCC.

METHODS

Patients with FLC and HCC in the Surveillance, Epidemiology, and End Results (SEER) database between 2000 and 2015 were included. Propensity score matching (PSM) was performed to balance the clinical characteristics between FLC and HCC. Cox regression and Kaplan-Meier analysis were applied to identify the effect of pathology in prognosis before and after match in the whole cohort, as well as in subgroups of fibrosis score, AJCC stage and therapy.

RESULTS

A total of 213 patients with FLC and 33365 patients with HCC between 2000 and 2015 were identified. Before matching, the overall survival (OS) and cancer-specific survival (CSS) were significantly better in FLC than HCC. After matching, FLC patients had better OS than HCC patients, but the CSS was similar between groups. Further analyses found that in patients at early stage (AJCC I-III) and/or accepted curative therapy, the prognosis was comparable between HCC and FLC. In patients without cirrhosis (F0), the HCC patients had similar prognosis with FLC patients. Prognosis benefit of FLC was observed in subgroups of AJCC stage IV and non-curative therapy, however, the concomitant diseases may affect the results.

CONCLUSIONS

The prognosis of FLC was significantly better than HCC before matching. However, after matching for clinical characteristics, the CSS was comparable between FLC and HCC.

A Multidisciplinary Approach to the Management of Fibrolamellar Carcinoma: Current Perspectives and Future Prospects

Fibrolamellar carcinoma (FLC) is a rare primary liver tumor affecting predominantly younger and otherwise healthy patients. Typically, FLC presents with advanced disease due to the paucity of typical symptoms and no history of underlying liver disease. Depending on tumor characteristics and the patient's general condition, surgical treatment is the most promising treatment modality. Aggressive resection and liver transplantation have been utilized and are presently indispensable curative treatment options. Under certain circumstances surgical resection is also possible for metachronous metastases or local recurrence. Recent tumor biology discoveries have contributed to improved diagnostic specificity and systemic treatment options.

Case Report of Fibrolamellar Hepatocellular Carcinoma in A 15-Year-old Male

Background

A rare form of hepatocellular cancer is called fibrolamellar hepatocellular carcinoma (FL-HCC) which occurs mostly in young adults who are medically free, regardless of their gender. It usually presents with abdominal pain with right upper quadrant palpable mass, nausea, and weight loss associated with higher Alpha-Fetoprotein (AFP) in some cases.

Objective

We report a case of a 15-year-old male patient who was diagnosed with (FL-HCC), successfully treated with surgical resection and is currently free of relapses.

Case presentation

A 15-year-old male patient with no previous medical or surgical history, presented with recurrent vomiting for two months, weight loss, and loss of appetite. Patient presented with normal systemic examination except for abdominal examination which revealed a generalized distended abdomen with mild tenderness in the right upper quadrant with the presence of hepatomegaly. Laboratory and radiological investigation showed high level of (AFP). CT and liver MRI showed large right hepatic lobe lesion then TRU-CUT needle biopsy was performed which showed Fibrolamellar hepatocellular carcinoma and patient underwent surgical resection with no postoperative complication followed by multiple cycle of chemotherapy and no signs of relapse with 3 year follow up.

Conclusion

Fibrolamellar hepatocellular carcinoma is rear type hepatocellular carcinoma which occurs mostly in young adults who are medically free with vague symptom and to diagnose it need high index of suspicion and variers Laboratory and radiological investigation including biopsy. However, it can be treated successfully by surgical resection followed by chemotherapy in selected cases if diagnosis in timely manner.

Fibrolamellar carcinoma: An entity all its own

Fibrolamellar carcinoma (FLC) is a rare malignant entity arising from the liver and primarily affecting patients in late adolescence and young adulthood. FLC tumors are characterized by their unique histologic features and an only recently discovered genomic alteration: a chimeric fusion protein found in nearly all tumors. The rarity of these tumors coupled with the only recent acknowledgement of this genomic abnormality has likely led to disease under-recognition and de-prioritization of collaborative efforts aimed at establishing an evidence-guided standard of care. Surgical resection undoubtedly remains a mainstay of therapy and a necessity for cure but given the incidence of metastatic disease at diagnosis and high rates of distant relapse, systemic therapies remain a key component of disease control. There are few systemic therapies that have demonstrated proven benefit. Recent efforts have galvanized around single-institute or small consortia-based studies specifically focused on the enrollment of patients with FLC or use of agents with biologic rationale. This review will outline the current state of FLC epidemiology, histology, biology and trialed therapies derived from available published literature.

Road map for fibrolamellar carcinoma: progress and goals of a diversified approach

Fibrolamellar carcinoma is a rare liver cancer, which primarily afflicts adolescents and young adults worldwide and is frequently lethal. Given the rarity of this disease, patient recruitment for clinical trials remains a challenge. In November 2017, the Second Fibrolamellar Cancer Foundation Scientific Summit (Stamford, CT, USA) provided an opportunity for investigators to discuss recent advances in the characterization of the disease and its surrounding liver and immune context. The Fibrolamellar Cancer Foundation has thus set out a road map to identify and test therapeutic targets in the most efficient possible manner.

Fibrolamellar Hepatocellular Carcinoma and Noncirrhotic Hyperammonemic Encephalopathy

Fibrolamellar hepatocarcinoma is an infrequent liver tumor, currently considered to be a variant different from hepatocarcinoma. The differences lie in genomic alterations, a greater prevalence of fibrolamellar hepatocarcinoma in young patients, and its lack of association with underlying liver disease. The clinical presentation is unspecific, with symptoms ranging from abdominal pain, malaise, and weight loss to atypical manifestation which include hyperammonemic encephalopathy. We present the case of a 33-year-old woman with no prior medical history who presented with a coma and a diagnosis of inoperable fibrolamellar hepatocarcinoma requiring a cadaver donor transplant. While she was on the waiting list, she received hemofiltration and ammonium benzoate treatment, with progressive improvement in her state of consciousness.

Environmental exposures as a risk factor for fibrolamellar carcinoma

Fibrolamellar carcinoma was first described in 1956. Subsequent large studies failed to identify cases before 1939 (the start of the World War II). This finding, combined with the presence of aryl hydrocarbon receptors on the tumor cells, have suggested that fibrolamellar carcinomas may be caused by environmental exposures that are new since World War II. To investigate this possibility, the surgical pathology files before 1939 were reviewed for hepatocellular carcinomas resected in young individuals. Two cases of fibrolamellar carcinoma were identified, from 1915 to 1924. The diagnosis of fibrolamellar carcinoma was confirmed at the histologic, ultrastructural and proteomic levels. These two fibrolamellar carcinoma cases clarify a key aspect of fibrolamellar carcinoma biology, reducing the likelihood that these tumors result exclusively from post World War II environmental exposures.

Hepatocellular Carcinoma, Fibrolamellar Variant: Diagnostic Pathologic Criteria and Molecular Pathology Update. A Primer

Fibrolamellar hepatocellular carcinoma (FL-HCC) is generally a fairly rare event in routine pathology practice. This variant of hepatocellular carcinoma (HCC) is peculiarly intriguing and,in addition, poorly understood. Young people or children are often the target individuals with this type of cancer. Previously, I highlighted some pathology aspects of FL-HCC, but in this review, the distinctive clinico-pathologic features of FL-HCC and the diagnostic pathologic criteria of FL-HCC are fractionally reviewed and expanded upon. Further, molecular genetics update data with reference to this specific tumor are particularly highlighted as a primer for general pathologists and pediatric histopathologists. FL-HCC may present with metastases, and regional lymph nodes may be sites of metastatic spread. However, peritoneal and pulmonary metastatic foci have also been reported. To the best of our knowledge, FL-HCC was initially considered having an indolent course, but survival outcomes have recently been updated reconsidering the prognosis of this tumor. Patients seem to respond well to surgical resection, but recurrences are common. Thus, alternative therapies, such as chemotherapy and radiation, are ongoing. Overall, it seems that this aspect has not been well-studied for this variant of HCC and should be considered as target for future clinical trials. Remarkably, FL-HCC data seem to point to a liver neoplasm of uncertain origin and unveiled outcome. A functional chimeric transcript incorporating DNAJB1 and PRKACA was recently added to FL-HCC. This sensational result may give remarkable insights into the understanding of this rare disease and potentially provide the basis for its specific diagnostic marker. Detection of DNAJB1-PRKACA seems to be, indeed, a very sensitive and specific finding in supporting the diagnosis of FL-HCC. In a quite diffuse opinion, prognosis of this tumor should be reconsidered following the potentially mandatory application of new molecular biological tools.

Fibrolamellar hepatocellular carcinoma: current clinical perspectives

Fibrolamellar carcinoma (FLC) is a variant of hepatocellular carcinoma (HCC), which comprises ∼1%–9% of all HCCs. Although FLC is a variant of HCC, it is distinct from HCC in that it most often affects younger patients (10–35 years of age) with no underlying liver disease. FLC often presents with vague abdominal pain, nausea, abdominal fullness, malaise, and weight loss. Surgery is the current mainstay of treatment for FLC and remains the only potentially curative option. While FLCs are considered less responsive to chemotherapy than their classic HCC counterparts, there have been suggestions that multimodality treatments may be effective, especially in advanced cases. Further research is necessary to determine effective systemic therapies as an adjunct to surgery for FLC.

Surgical treatment of fibrolamellar hepatocellular carcinoma: an underestimated malignant tumor?

BACKGROUND

Fibrolamellar hepatocellular carcinoma (FLHCC) is a rare disease with an indolent behavior. Its prognosis is better than that of patients with hepatocellular carcinoma. The authors present their experience with resection of FLHCC.

METHODS

Twenty-one patients with FLHCC were treated at our institution between 1990 and 2012. Of these patients, 14 were subjected to resection of the tumor. Patient demographics, medical history, results of imaging studies and laboratory tests, surgical data, and pathologic findings were evaluated.

RESULTS

The median age of the patients at the diagnosis of the tumor was 20 years and 14 patients were female. None of the patients had tumor-associated chronic liver disease or cirrhosis. The mean tumor size was 12.8 cm (range 6-19) and 18 patients had a single liver nodule. Fourteen patients were subjected to hepatectomy and six of them had lymph node metastases resected. Pathologic evaluation revealed that 5 (35.7%) patients had major vascular invasion. Tumor recurrence was seen in 8 patients (66.7%), during a follow-up. The median survival time for patients who were subjected to resection was 36 months. The 5-year overall survival rate and disease free survival rate were 28.0% and 8.5%, respectively. Univariate analysis showed that vascular invasion was the only variable associated with the disease free survival rate.

CONCLUSIONS

Despite an aggressive treatment, patients with FLHCC presented unexpected low survival rates. It seems that an underestimated malignant behavior is attributed to this disease, and that the forms of adjuvant treatment should be urgently evaluated.

Vitamin B₁₂ and its binding proteins in hepatocellular carcinoma and chronic liver diseases

BACKGROUND

The vitamin B12 (B12)-binding protein haptocorrin (HC) has proven to be a potentially useful biomarker in patients with fibrolamellar hepatocellular carcinoma (HCC). Little is known concerning the level of HC and other B12-related proteins in patients with HCC as compared to patients with other chronic liver diseases (CLDs) and healthy controls. We hypothesized that HC could be a biomarker of HCC.

AIMS

To investigate levels of HC and B12-related proteins in HCC compared to CLDs and healthy controls.

METHODS

We investigated two patient populations: A cross-sectional cohort of HCC patients (n = 130), CLD patients (n = 102) and healthy controls (n = 46) and a cohort of 38 HCC patients studied at baseline and 1, 4, and 12 weeks following ablative treatment. Patients were evaluated by standard biochemistry, Child-Pugh-score and Barcelona Clinic Liver Cancer (BCLC) classification. We analyzed total B12 by routine methods and HC, transcobalamin (TC), B12 saturated TC (holoTC), and the soluble cell surface receptor for holoTC (sCD320) by in-house enzyme-linked immunosorbent assay.

RESULTS

HC showed higher median (range) levels for both HCC (590 [290-5860]) and CLD patients (620 [310-4010]) compared to controls (460 [250-2020]) (p < 0.01). Total B12, TC, holoTC, and sCD320 showed elevated levels in both HCC and CLD compared to controls. Only holoTC changed following treatment, without a concurrent change in TC.

CONCLUSION

B12 and B12-related proteins (total B12, HC, TC, holoTC, and sCD320) show elevations in both HCC and CLD patients compared to controls, suggesting a relation to CLD in general rather than to primary liver cancer. Thus, HC is not useful as a biomarker for HCC.

Typical fibrolamellar hepatocellular carcinoma in a Japanese boy: report of a case

We report a case of typical fibrolamellar hepatocellular carcinoma (FL-HCC) in a 16-year-old Japanese boy. This is very rare malignancy in Japan. The patient was referred for investigation of a large hepatic tumor and the results of tests for hepatitis B virus surface antigen and hepatitis C virus antibody were negative. Liver function test results and serum alpha-fetoprotein (AFP) levels were normal; however, the prothrombin induced by vitamin K absence/antagonist II was elevated. Computed tomography (CT) showed a large lobulated heterogeneously enhanced tumor in the posterior section of the liver. We diagnosed FL-HCC and performed posterior sectionectomy of the liver. The resected specimen contained a light brown and green tumor with a central fibrous scar, 10.0 cm in diameter. Microscopic and electron microscopic examinations revealed the typical features of FL-HCC. Immunohistochemically, the tumor cells were positive for cytokeratin (CK) 7, but negative for CK19 and AFP. The patient was alive without recurrence 48 months after surgery. Following this case report, we summarize the clinical features of the Japanese cases documented in the literature.

Fibrolamellar variant of hepatocellular carcinoma

The fibrolamellar variant of hepatocellular carcinoma is a rare primary liver cancer occurring in adolescents and young adults without chronic liver disease or known risk factors. Histologically, it is defined by lamellar bands of fibrosis surrounding well-differentiated tumor cells. Radiologic imaging typically demonstrates a large, solitary mass with calcifications and a central scar. Lymph node metastases in the porta hepatis are frequently diagnosed upon presentation. More patients with fibrolamellar carcinoma are candidates for surgical resection than those with conventional hepatocellular carcinoma, owing to their young age and absence of cirrhosis. The most important prognostic factor is surgical resection, which results in 5-year overall survival rates ranging between 50 and 76 %. Despite complete surgical resection, relapse rates are high, and novel therapies are needed to prevent and treat recurrent disease.

Fibrolamellar carcinoma: 2012 update

Fibrolamellar carcinomas are a unique type of primary liver cancer. They occur most commonly in children and young adults. Their etiology remains a mystery, as they are not associated with chronic liver disease. Fibrolamellar carcinomas are not indolent tumors, but have an overall better prognosis than typical hepatocellular carcinomas, in part because of the younger age at presentation and the lack of cirrhosis. The most important prognostic feature is whether the tumor is resectable. Histologically, the tumor is made up of large cells that contain abundant mitochondria. The nuclei of the tumor cells have prominent nucleoli. The tumor cells induce the formation of extensive intratumoral fibrosis, which often grows in parallel, or lamellar bands. The tumor cells clearly show hepatocellular features but are also unique in showing both biliary and neuroendocrine differentiation. The uniqueness of fibrolamellar carcinoma extends to their molecular findings. While the genetic abnormalities that lead to fibrolamellar carcinomas are not yet known, studies have shown that they lack mutations in the genes most commonly mutated in typical hepatocellular carcinoma (TP53 and CTNNB1). In this paper, the clinical, pathological, and basic science literature on fibrolamellar carcinoma is comprehensively reviewed. Key areas of needed research are also discussed.

A systematic review: treatment and prognosis of patients with fibrolamellar hepatocellular carcinoma

BACKGROUND

Fibrolamellar hepatocellular carcinoma (FLC) is a rare primary liver tumor presenting earlier in life than nonfibrolamellar hepatocellular carcinoma (NFL-HCC), with distinct epidemiologic and clinical characteristics. Although FLC is believed to have a better prognosis than NFL-HCC, data on treatment and prognosis are scarce. We performed a systematic review to investigate treatment options and clinical outcomes of patients with FLC.

STUDY DESIGN

The study is a systematic review of the literature and pooled analysis of individual patient data.

RESULTS

A total of 35 series were analyzed, reporting on 575 patients (52% female, elevated alpha-fetoprotein in 10%, cirrhosis in 3%, hepatitis B in 2%), most of whom were treated with partial hepatectomy (55%) or orthotopic liver transplantation (23%). Nineteen studies provided data on 206 individual patients with a median age of 21 years and tumor size of 12 cm. Median overall survival (OS) was 39 months; 1-year, 3-year, and 5-year OS rates were 85%, 53%, and 44%, respectively. For patients treated with liver resection, median OS was 18.5 years and 1-year, 3-year, and 5-year OS were 93%, 80%, and 70%, respectively. Based on data from 15 studies, FLC appeared to follow a relatively indolent course compared with NFL-HCC.

CONCLUSIONS

Patients with FLC treated with partial hepatectomy have excellent long-term survival, with 5-year overall survival reaching 70%. Patients fared worse with the use of other therapeutic options including chemotherapy, intra-arterial therapy, and transplantation, although data directly comparing resection vs transplantation were limited.

Fibrolamellar hepatocellular carcinoma: a case report with distinct radiological features

INTRODUCTION

We report a rare case of a 23-year-old male who presented with abdominal discomfort for 15 days. An ultrasound was performed which showed a hypoechoic, heterogenous mass in the left lobe of the liver and distended portal vein, followed by further investigation with computed tomography (CT), MRI, and MRA. Serum alpha-fetoprotein was not elevated and hepatitis B antigen was negative.

METHODS

CT scan depicted a nodular mass in left liver lobe with occlusion of both the central part and the two main branches of intrahepatic portal vein.

RESULT

Biopsy of the liver mass led to a diagnosis of fibrolamellar hepatocellular carcinoma.

CONCLUSION

Fibrolamellar carcinoma is an uncommon variant of hepatocellular carcinoma. The diagnosis is suggested by radiographic studies and is confirmed by histological examination.

Fibrolamellar hepatocellular carcinoma

Fibrolamellar hepatocellular carcinoma (FHLCC) generally occurs in young individuals lacking a background of chronic liver disease and other risk factors for hepatocellular carcinoma. The clinical presentations of FLHCC are generally nonspecific, and the alpha-fetoprotein level is typically within the normal range in most cases. Imaging studies have a major role in clinical diagnosis, but pathology is the gold standard in confirming diagnosis. Pathological characteristics of FLHCC include the presence of tumor cells with a deeply eosinophilic cytoplasm and macronucleoli surrounded by abundant fibrous bands. The most effective treatment for FLHCC is aggressive surgical resection. This comprehensive literature review gives a full account of the clinical, pathological, and molecular features of FLHCC.

Fibrolamellar hepatocellular carcinoma: prolonged survival with multimodality therapy

AIM

We report the clinical outcome for a series of ten patients with fibrolamellar hepatocellular treated with resection followed by close surveillance and aggressive management of relapse.

METHODS

The case notes for all patients treated at this institution since 1982 were reviewed and details of initial stage and management were extracted along with investigations and treatment of relapse. Time to relapse, overall survival and post-relapse survival were analysed.

RESULTS

Relapse occurred in all ten cases at a median of 2.2 (95% CI 0.9-2.7) years but, with a combination of re-resection, systemic chemotherapy and radiotherapy, the overall median survival was 9.3 (95% CI 3.0-18.5) years. One patient was disease free eight years after two resections for recurrent disease. Two of nine patients had a partial response to cisplatin and fluorouracil while three had stable disease. FDG-PET was positive for recurrence in three of four cases of relapse, and in one case detected recurrence in advance of CT.

CONCLUSION

The early detection of relapse combined with multimodality therapy results in prolonged survival. Further improvements in systemic therapy are required to improve the prognosis in this disease.

Haptocorrin in humans

BACKGROUND

Evolutionary haptocorrin is the youngest of the cobalamin-binding proteins. It evolved by duplication of the intrinsic factor gene and has been identified in most mammals examined. Its ability to bind both cobalamin and analogues is well established, but apart from that, our knowledge concerning its function and its distribution in adult and foetal life is limited. In this study, we present data on the tissue expression of haptocorrin and on the relation between analogues on haptocorrin and vitamin B(12) status in humans.

METHODS

Polyclonal antibodies towards haptocorrin were used to study the localisation in foetal and adult tissues by immunohistochemistry. Positive immunoreactions were primarily observed in exocrine glands, the gastrointestinal tract and the respiratory system. ELISA was used for measurement of holo- and total haptocorrin in blood samples from individuals diagnosed with vitamin B(12) deficiency, based on measurement of methylmalonic acid (micromol/L) as evident (>0.75, n=61), suspected (0.29-0.75, n=155) or not present (<0.29, n=170). Cobalamins and holotranscobalamin were measured in the same individuals.

RESULTS

Holohaptocorrin was considerably higher than holohaptocorrin-cobalamins (cobalamins minus holotranscobalamin). The median (25th-75th percentile, pmol/L) for holohaptocorrin analogues (holohaptocorrin minus holohaptocorrin-cobalamins) was higher in deficient [200 (130-240)] compared to the non-deficient [140 (80-200)] individuals (analysis of variance and Tukey's multiple comparison test, p<0.01).

CONCLUSIONS

Our results indicate that haptocorrin is widely distributed also in foetal tissues and suggest analogues to accumulate on haptocorrin in vitamin B(12)-deficient individuals, a result that warrants further studies employing methods directly measuring cobalamins and analogues attached to haptocorrin.

Review of the clinicopathologic features of fibrolamellar carcinoma

Since its first description 50 years ago, fibrolamellar carcinomas (FLCs) have been recognized as a unique type of primary liver cancer. FLCs occur principally in children and young adults and are not associated with chronic liver disease. Their etiology is unknown. The tumor is made up of large polygonal cells containing abundant eosinophilic cytoplasm, large vesiculated nuclei, and large nucleoli, with tumor cells that are embedded in lamellar bands of fibrosis. Although rare, the most common variant of FLC shows areas of glandular type differentiation with mucin production. The uniqueness of FLC extends to their molecular findings, as they show no evidence for involvement by many of the major pathways and genes that are dysregulated in typical hepatocellular carcinoma, including alpha-fetoprotein, TP53 mutations, and beta catenin mutations. FLCs are not indolent tumors, but have an overall better prognosis than hepatocellular carcinomas of the usual sort because of the younger age at presentation and lack of cirrhosis. The most important prognostic feature is resectability. Although their morphologic appearance on routine stains is well defined, their etiology is still unknown and much of their molecular biology remains poorly described and awaits future investigation.

[Fibrolamellar carcinoma]

Fibrolamellar carcinoma (FL-Ca) is a primary malignant liver tumor at unknown etiology, without cirrhosis and usually without an increase at tumor markers, which occurs mainly in young patients. As it can simulate malignant and benign tumors, particularly FNH, diagnosis is difficult. Ultrasound and angiography show mostly uncharacteristic features. The highest specificity has CT, if calcifications are present, because these calcifications in a tumor similar to FNH are pathognomonic for FL-Ca. In MRI the central scars of FL-Ca and FNH have a different signal intensity in T2-weighted images, so that MRI becomes more and more important in the differential diagnosis to FNH.