Macrotrabecular Hepatocellular Carcinoma

Deep Learning Classification and Quantification of Pejorative and Nonpejorative Architectures in Resected Hepatocellular Carcinoma from Digital Histopathologic Images

Liver resection is one of the best treatments for small hepatocellular carcinoma (HCC), but post-resection recurrence is frequent. Biotherapies have emerged as an efficient adjuvant treatment, making the identification of patients at high risk of recurrence critical. Microvascular invasion (mVI), poor differentiation, pejorative macrotrabecular architectures, and vessels encapsulating tumor clusters architectures are the most accurate histologic predictors of recurrence, but their evaluation is time-consuming and imperfect. Herein, a supervised deep learning-based approach with ResNet34 on 680 whole slide images (WSIs) from 107 liver resection specimens was used to build an algorithm for the identification and quantification of these pejorative architectures. This model achieved an accuracy of 0.864 at patch level and 0.823 at WSI level. To assess its robustness, it was validated on an external cohort of 29 HCCs from another hospital, with an accuracy of 0.787 at WSI level, affirming its generalization capabilities. Moreover, the largest connected areas of the pejorative architectures extracted from the model were positively correlated to the presence of mVI and the number of tumor emboli. These results suggest that the identification of pejorative architectures could be an efficient surrogate of mVI and have a strong predictive value for the risk of recurrence. This study is the first step in the construction of a composite predictive algorithm for early post-resection recurrence of HCC, including artificial intelligence-based features.

Outcomes in Patients with Macrotrabecular-Massive Subtype Hepatocellular Carcinoma Treated with Yttrium-90 Transarterial Radioembolization

PURPOSE

To compare the outcomes of yttrium-90 transarterial radioembolization (TARE) in patients with hepatocellular carcinoma (HCC) with and without macrotrabecular-massive (MTM) subtypes.

MATERIALS AND METHODS

Forty-one consecutive patients with HCC (male, 90.3%; mean age, 65.3 years [SD ± 10.7]) who underwent yttrium-90 TARE between September 2014 and January 2022 were grouped into the MTM-HCC (n = 17, 41.5%) and non-MTM-HCC (n = 24, 58.5%) groups based on their histopathological subtypes. Demographic, clinical, and radiological characteristics were compared. Survival, univariate, and multivariate analyses were performed, and prognostic factors were evaluated.

RESULTS

In MTM-HCC group, the rates of moderately to poorly differentiated tumors were significantly higher (13/17 vs 8/16, P = .007), and new intrahepatic/extrahepatic metastases were detected more frequently (12/17 vs 15/24, P = .038). Median overall survival (OS) in the cohort was 29 months (range, 17.1-40.9 months), whereas patients with MTM-HCC had a significantly shorter median OS (20 vs 44 months, P = .014). In univariate analysis, MTM-HCC subtype (hazard ratio [HR], 2.690; P = .021), the presence of satellite nodules (HR, 3.810; P = .004), and macrovascular invasion (HR, 3.321; P = .012) were identified as significant prognostic factors. In multivariate analysis, MTM-HCC subtype and macrovascular invasion were determined as independent poor prognostic factors (P = .038 and P = .012, respectively).

CONCLUSIONS

In patients with HCC treated with yttrium-90 TARE, both the rates of moderately to poorly differentiated histopathological classes and the development of intrahepatic or extrahepatic metastases were significantly higher in the MTM-HCC subtype. OS was worse in patients with MTM-HCC, and macrovascular invasion and MTM-HCC subtype were identified as independent poor prognostic factors.

Histological predictors of aggressive recurrence of hepatocellular carcinoma after liver resection

BACKGROUND & AIMS

Assessment of recurrence risk after liver resection (LR) is critical in hepatocellular carcinoma (HCC), particularly with the advent of effective adjuvant therapy. The aim of this study was to analyze the clinical and pathological factors associated with recurrence, aggressive recurrence, and survival after LR.

METHOD

We performed a retrospective study in which all single HCC (BCLC-0/A) patients treated with LR between February 2000 and November 2020 were included. The main clinical variables were recorded. Histological features were blindly evaluated by two independent pathologists. Aggressive recurrence was defined as those that exceeded the Milan criteria at 1st recurrence.

RESULTS

A total of 218 patients were included (30% BCLC 0 and 70% BCLC A), median (IQR) tumor size of 28 (19-42 mm). The prevalence of microvascular invasion and/or satellitosis (mVI/S) was 39%, with a kappa-index between both pathologists of 0.8. After a median follow-up of 49 (23-85) months, 61/218 (28%) patients died, 32/218 (15%) underwent liver transplantation, 127 (58%) developed HCC recurrence. The prevalence of aggressive recurrence was 35% (44/127 Milan-out, with 20 cases at advanced stage), and the 5-year survival rate was 81%. The presence of mVI/S was the only independent predictor of recurrence (hazard ratio [HR] 1.83, 95% CI 1.28-2.61, p <0.001), aggressive recurrence (HR 3.31, 95% CI 1.74-6.29, p <0.001) and mortality (HR 2.23, 95% CI 1.27-3.91, p = 0.005). The macrotrabecular-massive subtype was significantly associated with a higher prevalence of mVI/S, Edmonson Steiner grade III-IV, AFP values and vessels that encapsulate tumor clusters, but not with recurrence, aggressive recurrence, or overall survival.

CONCLUSION

The presence of mVI/S was the only independent risk factor for aggressive recurrence and mortality. This has important implications for early-stage patient management, especially in the setting of adjuvant immunotherapy or ab initio LT.

IMPACT AND IMPLICATIONS

Assessment of recurrence risk after liver resection is crucial in patients with hepatocellular carcinoma. Patients with a high risk of recurrence are candidates for liver transplantation as an ab initio indication or for the potential use of adjuvant therapy. Aggressive recurrences, defined as those exceeding the Milan criteria at first recurrence, have a significant impact on overall survival (OS). Fifty-eight percent of patients experienced hepatocellular carcinoma recurrence, with a prevalence of aggressive recurrence at the first occurrence standing at 35%. After a median follow-up of 49 (23-85) months, 61 (28%) patients died, and 32 (15%) underwent liver transplantation, resulting in a 5-year OS rate of 81%. Microvascular invasion and/or satellitosis was present in 39% of our cohort and was the only independent predictor of recurrence, aggressive recurrence, and OS on multivariate analysis. This is important as it could be used to guide therapeutic management.

Diagnostic and Prognostic Ability of Contrast-Enhanced Unltrasound and Biomarkers in Hepatocellular Carcinoma Subtypes

OBJECTIVE

To investigate the diagnostic and prognostic value of contrast-enhanced ultrasound (CEUS) and clinical indicators of the vessels encapsulating tumor clusters (VETC) pattern and macrotrabecular-massive subtype in hepatocellular carcinoma (MTM-HCC).

METHODS

This retrospective study included patients who underwent preoperative CEUS and hepatectomy for HCC between August 2018 and August 2021. Multivariable logistic regression was performed to select independent correlated factors of VETC-HCC and MTM-HCC to develop nomogram models. The association between model outcomes and early postoperative HCC recurrence was assessed using Kaplan-Meier curve and Cox regression analysis.

RESULTS

The training cohort included 182 patients (54.3 ± 11.3 years, 168 males) and the validation cohort included 91 patients (54.8 ± 10.6 years, 81 males). Multivariate logistic regression analysis revealed that α-fetoprotein (AFP) levels (odds ratio [OR]: 2.26, 95% confidence interval [CI]: 1.49-3.42, p < 0.001), intratumoral nonenhancement (OR: 2.40, 95% CI: 1.02-5.64, p = 0.044), and the perfusion pattern in the CEUS arterial phase (OR: 2.27, 95% CI: 1.05-4.91, p = 0.038) were independent predictors of VETC-HCC. Besides, the former two were also independently associated with MTM-HCC (AFP level: OR: 2.36, 95% CI: 1.36-4.09, p = 0.002; intratumoral nonenhancement: OR: 3.72, 95% CI: 1.02-13.56, p = 0.046). Nomogram models were constructed based on the aforementioned indicators. Kaplan-Meier curve analysis indicated that predicted VETC-HCC or MTM-HCC exhibited higher rates of early recurrence (log-rank p < 0.001 and p = 0.002, respectively). Cox regression analysis showed that a high risk of VETC-HCC was independently correlated with early recurrence (p = 0.011).

CONCLUSION

CEUS combined with AFP levels can predict VETC-HCC/MTM-HCC and prognosis preoperatively.

Hepatocellular Carcinoma: Optimal Radiological Evaluation before Liver Transplantation

Liver transplantation (LT) is the recommended curative-intent treatment for patients with early or intermediate-stage hepatocellular carcinoma (HCC) who are ineligible for resection. Imaging plays a central role in staging and for selecting the best LT candidates. This review will discuss recent developments in pre-LT imaging assessment, in particular LT eligibility criteria on imaging, the technical requirements and the diagnostic performance of imaging for the pre-LT diagnosis of HCC including the recent Liver Imaging Reporting and Data System (LI-RADS) criteria, the evaluation of the response to locoregional therapy, as well as the non-invasive prediction of HCC aggressiveness and its impact on the outcome of LT. We will also briefly discuss the role of nuclear medicine in the pre-LT evaluation and the emerging role of artificial intelligence models in patients with HCC.

Understanding the causes of recurrent HCC after liver resection and radiofrequency ablation

INTRODUCTION

Surgical resection and radiofrequency ablation are preferred options for early-stage disease, with 5-year recurrence rates as high as 70% when patients are treated according to guidelines. With increasing availability of therapeutic options, including but not limited to, immune-checkpoint inhibitors (ICI), tyrosine kinase inhibitors, antiangiogenics, and adoptive cell therapies, understanding the causes of recurrence and identifying its predictors should be priorities in the hepatocellular carcinoma (HCC) research agenda.

AREAS COVERED

Current knowledge of HCC predictors of recurrence is reviewed, and recent insights about its underlying mechanisms are presented. In addition, results from recent clinical trials investigating treatment combinations are critically appraised.

EXPERT OPINION

HCC recurrence is either due to progressive growth of microscopic residual disease, or to de novo cancer development in the context of a diseased liver, each occurring in an early (<2years) vs. late (≥2 years) fashion. Collectively, morphological, proteomic, and transcriptomic data suggest vascular invasion and angiogenesis as key drivers of HCC recurrence. Agents aimed at blocking either of these two hallmarks should be prioritized at the moment of early-stage HCC clinical trial design. Emerging results from clinical trials testing ICI in early-stage HCC underscore the importance of defining the best treatment sequence and the most appropriate combination strategies. Lastly, as different responses to systemic therapies are increasingly defined according to the HCC etiology, patient enrolment into clinical trials should take into account the biological characteristics of their inherent disease.

Macrotrabecular-massive subtype-based nomogram to predict early recurrence of hepatocellular carcinoma after surgery

OBJECTIVES

To analyze the predictive factors on early postoperative recurrence of hepatocellular carcinoma (HCC) and to establish a new nomogram to predict early postoperative recurrence of HCC.

METHODS

A retrospective analysis of 383 patients who had undergone curative resection between February 2012 and September 2020 in our center was performed. The Kaplan-Meier method was used for survival curve analysis. Univariate and multivariate Cox regression were performed to identify independent risk factors associated with early recurrence, and a nomogram for predicting early recurrence of HCC was established.

RESULTS

A total of 152/383 patients developed recurrence after surgery, of which 83 had recurrence within 1 year. Multivariate Cox regression analysis showed that preoperative alpha-fetoprotein level ≥400 ng/ml (P = 0.001), tumor diameter ≥5 cm (P = 0.009) and MVI (P = 0.007 and macrotrabecular-massive HCC (P = 0.003) were independent risk factors for early postoperative recurrence of HCC. The macrotrabecular-massive-based nomogram obtained a good C-index (0.74) for predicting early recurrence of HCC, and the area under the curve for predicting early recurrence was 0.767, which was better than the single American Joint Committee on Cancer T stage and Barcelona Clinic Liver Cancer stage.

CONCLUSIONS

The nomogram based on macrotrabecular-massive HCC can effectively predict early postoperative recurrence of HCC.

Histological subtypes of hepatocellular carcinoma: Their clinical and prognostic significance

Assigning a hepatocellular carcinoma (HCC) to an appropriate subtype is important because this guarantees the diagnosis and treatment and allows decisions regarding the prognosis of the patient. HCC subtyping is usually based on the World Health Organization (WHO) classification and the 2019 fifth edition is the latest version. However, the WHO classification system is still in evolution and has limited clinical relevance. We aimed to evaluate the clinical relevance of HCC subtyping and to reappraise some of the major subtypes of HCC. Our archived cases (n = 589) were reclassified according to the 2019 WHO system. The percentage of each subtype was mostly similar to that in the WHO classification. However, on the contrary to the 2019 WHO system, clear cell type HCC was associated with more frequent recurrence or metastasis. Meanwhile, macrotrabecular massive HCC was related to poor prognosis as demonstrated in the 2019 WHO system and should be described in the pathology report. For steatohepatitic HCC, there is a debate on whether it is a true subtype because the steatohepatitis morphology may or may not be present in the background liver. In our study, 44 % of steatohepatitic HCCs (n = 19/43) presented underlying steatohepatitis. Additionally, the background cirrhosis did not influence survival in the HCC patients, although the 2019 WHO system indicates the presence of cirrhosis as a poor prognostic factor. In conclusion, although it is not perfect yet, HCC subtyping based on the 2019 WHO system provides valuable information to manage patients with HCC.

Radiomics: A radiological evidence-based artificial intelligence technique to facilitate personalized precision medicine in hepatocellular carcinoma

The high postoperative recurrence rates in hepatocellular carcinoma (HCC) remain a major hurdle in its management. Appropriate staging and treatment selection may alleviate the extent of fatal recurrence. However, effective methods to preoperatively evaluate pathophysiologic and molecular characteristics of HCC are lacking. Imaging plays a central role in HCC diagnosis and stratification due to the non-invasive diagnostic criteria. Vast and crucial information is hidden within image data. Other than providing a morphological sketch for lesion diagnosis, imaging could provide new insights to describe the pathophysiological and genetic landscape of HCC. Radiomics aims to facilitate diagnosis and prognosis of HCC using artificial intelligence techniques to harness the immense information contained in medical images. Radiomics produces a set of archetypal and robust imaging features that are correlated to key pathological or molecular biomarkers to preoperatively risk-stratify HCC patients. Inferred with outcome data, comprehensive combination of radiomic, clinical and/or multi-omics data could also improve direct prediction of response to treatment and prognosis. The evolution of radiomics is changing our understanding of personalized precision medicine in HCC management. Herein, we review the key techniques and clinical applications in HCC radiomics and discuss current limitations and future opportunities to improve clinical decision making.

Development and validation of MRI-based model for the preoperative prediction of macrotrabecular hepatocellular carcinoma subtype

BACKGROUND

Macrotrabecular hepatocellular carcinoma (MTHCC) has a poor prognosis and is difficult to diagnose preoperatively. The purpose is to build and validate MRI-based models to predict the MTHCC subtype.

METHODS

Two hundred eight patients with confirmed HCC were enrolled. Three models (model 1: clinicoradiologic model; model 2: fusion radiomics signature; model 3: combined model 1 and model 2) were built based on their clinical data and MR images to predict MTHCC in training and validation cohorts. The performance of the models was assessed using the area under the curve (AUC). The clinical utility of the models was estimated by decision curve analysis (DCA). A nomogram was constructed, and its calibration was evaluated.

RESULTS

Model 1 is easier to build than models 2 and 3, with a good AUC of 0.773 (95% CI 0.696-0.838) and 0.801 (95% CI 0.681-0.891) in predicting MTHCC in training and validation cohorts, respectively. It performed slightly superior to model 2 in both training (AUC 0.747; 95% CI 0.689-0.806; p = 0.548) and validation (AUC 0.718; 95% CI 0.618-0.810; p = 0.089) cohorts and was similar to model 3 in the validation (AUC 0.866; 95% CI 0.801-0.928; p = 0.321) but inferior in the training (AUC 0.889; 95% CI 0.851-0.926; p = 0.001) cohorts. The DCA of model 1 had a higher net benefit than the treat-all and treat-none strategy at a threshold probability of 10%. The calibration curves of model 1 closely aligned with the true MTHCC rates in the training (p = 0.355) and validation sets (p = 0.364).

CONCLUSION

The clinicoradiologic model has a good performance in diagnosing MTHCC, and it is simpler and easier to implement, making it a valuable tool for pretherapeutic decision-making in patients.

CT Radiomics to Predict Macrotrabecular-Massive Subtype and Immune Status in Hepatocellular Carcinoma

Background Macrotrabecular-massive (MTM) subtype of hepatocellular carcinoma (HCC) is an aggressive variant associated with angiogenesis and immunosuppressive tumor microenvironment, which is expected to be noninvasively identified using radiomics approaches. Purpose To construct a CT radiomics model to predict the MTM subtype and to investigate the underlying immune infiltration patterns. Materials and Methods This study included five retrospective data sets and one prospective data set from three academic medical centers between January 2015 and December 2021. The preoperative liver contrast-enhanced CT studies of 365 adult patients with resected HCC were evaluated. The Third Xiangya Hospital of Central South University provided the training set and internal test set, while Yueyang Central Hospital and Hunan Cancer Hospital provided the external test sets. Radiomic features were extracted and used to develop a radiomics model with machine learning in the training set, and the performance was verified in the two test sets. The outcomes cohort, including 58 adult patients with advanced HCC undergoing transarterial chemoembolization and antiangiogenic therapy, was used to evaluate the predictive value of the radiomics model for progression-free survival (PFS). Bulk RNA sequencing of tumors from 41 patients in The Cancer Genome Atlas (TCGA) and single-cell RNA sequencing from seven prospectively enrolled participants were used to investigate the radiomics-related immune infiltration patterns. Area under the receiver operating characteristics curve of the radiomics model was calculated, and Cox proportional regression was performed to identify predictors of PFS. Results Among 365 patients (mean age, 55 years ± 10 [SD]; 319 men) used for radiomics modeling, 122 (33%) were confirmed to have the MTM subtype. The radiomics model included 11 radiomic features and showed good performance for predicting the MTM subtype, with AUCs of 0.84, 0.80, and 0.74 in the training set, internal test set, and external test set, respectively. A low radiomics model score relative to the median value in the outcomes cohort was independently associated with PFS (hazard ratio, 0.4; 95% CI: 0.2, 0.8; P = .01). The radiomics model was associated with dysregulated humoral immunity involving B-cell infiltration and immunoglobulin synthesis. Conclusion Accurate prediction of the macrotrabecular-massive subtype in patients with hepatocellular carcinoma was achieved using a CT radiomics model, which was also associated with defective humoral immunity. Published under a CC BY 4.0 license. Supplemental material is available for this article. See also the editorial by Yoon and Kim in this issue.

Preoperative prediction of macrotrabecular-massive hepatocellular carcinoma based on B-Mode US and CEUS

OBJECTIVES

To develop a preoperative prediction model to identify macrotrabecular-massive hepatocellular carcinoma (MTM-HCC) and evaluate the model's diagnostic performance in differentiating MTM-HCC from HCC.

METHODS

We conducted a mono-center retrospective study in a grade A tertiary hospital in China. Consecutive patients with suspected HCC from February 2019 to December 2020 were eligible for inclusion. All consenting patients underwent CEUS examination and were histologically diagnosed. Based on the clinical and US features between the two groups, we developed a binary logistic regression model and a nomogram for predicting MTM-HCC.

RESULTS

A total of 161 patients (median age, 57 years; interquartile range, 48-64 years; 129 men) were included in the analysis. Twenty-seven of the HCCs (16.8%) were of the MTM subtype. Binary logistic regression analysis indicated that PVP hypoenhancement (OR = 15.497; 95% CI: 1.369, 175.451; p = 0.027), AFP > 454.6 ng/mL (OR = 8.658; 95% CI: 3.030, 24.741; p < 0.001), ALB ≤ 29.9 g/L (OR = 3.937; 95% CI: 1.017, 15.234; p = 0.047), halo sign (OR = 3.868; 95% CI: 1.314, 11.391; p = 0.016), and intratumoral artery (OR = 2.928; 95% CI: 1.039, 8.255; p = 0.042) were predictors for MTM subtype. Combining any two criteria showed a high sensitivity (100.0%); combining all five criteria showed a high specificity (99.2%); and the AUC value of the logistic regression model was 0.88 (95% CI: 0.81, 0.92).

CONCLUSIONS

BMUS and CEUS could be used for identifying patients suspected of having MTM-HCC. Combining clinical information, BMUS, and CEUS features could achieve a noninvasive diagnosis of MTM-HCC.

KEY POINTS

• Contrast-enhanced ultrasound examination helps clinicians to identify MTM-HCCs preoperatively. • PVP hypoenhancement, high AFP levels, low ALB levels, halo signs, and intratumoral arteries could be used to predict MTM-HCCs. • A logistic regression model and nomogram were built to noninvasively diagnose MTM-HCCs with an AUC value of 0.88 (95% CI: 0.81, 0.92).

Imaging and histological features of tumor biopsy sample predict aggressive intrasegmental recurrence of hepatocellular carcinoma after radiofrequency ablation

Aggressive intrasegmental recurrence (AIR) is a form of local recurrence associated with a dismal prognosis and defined by multiple nodules or by an infiltrative mass with a tumor thrombus, occurring in the treated segment, after radiofrequency ablation (RFA) for hepatocellular carcinoma (HCC). We aimed to identify radiological and/or histological characteristics of tumor biopsy predictive of AIR. We retrospectively analyzed patients treated by No-Touch multi-bipolar RFA (mbpRFA) for a first HCC with a systematic per-procedural tumor biopsy positive for diagnosis of HCC. The first recurrence was classified as non-aggressive local recurrence, AIR or intrahepatic distant recurrence. 212 patients were included (168 men; mean age 67.1 years; mean tumor size 28.6 mm, 181 cirrhosis). AIR occurred in 21/212 patients (10%) and was associated with a higher risk of death (57% in patients with AIR vs 30% without AIR, p = 0.0001). Non-smooth tumor margins, observed in 21% of the patients and macro-trabecular massive histological subtype, observed in 12% of the patients were independently related to a higher risk of AIR (HR: 3.7[1.57;9.06], p = 0.002 and HR:3.8[2.47;10], p = 0.005 respectively). Non smooth margins at imaging and macro-trabecular massive histological subtype are associated with AIR and could be considered as aggressive features useful to stratify therapeutic strategy.

Prognostic impact of vessels encapsulating tumor clusters and macrotrabecular patterns in hepatocellular carcinoma

BACKGROUND

Hepatocellular carcinoma (HCC) shows a high mortality rate. A macrotrabecular (MT) pattern and vessels encapsulating tumor clusters (VETC) pattern have been reported as aggressive histological patterns in HCC. However, their cut-off values have been contentious.

METHOD

Nine hundred eighty-five cases of previously diagnosed HCC were enrolled. The percentage areas of the MT and/or VETC pattern with ≥ 5% at every 10% increment were assessed. Clinicopathological analysis including patients' prognosis was conducted.

RESULT

One hundred fifty-eight and eighty-four cases were accompanied by 5-49% and ≥ 50% MT components, respectively. Two hundred six and twenty-nine cases had 5-49% and ≥ 50% VETC components, respectively. Cases with these histological patterns in common had aggressive characteristics and worse prognosis compared to cases with none of these patterns. The presence of 5-49% VETC pattern was independent worse prognostic factor in overall survival (P = 0.046). HCCs with the MT pattern and the VETC pattern were significantly accompanied by the VETC pattern and the MT pattern (P < 0.001), respectively.

CONCLUSION

As even 5% of the MT pattern and/or VETC pattern affected the prognosis of patients with HCC, the amount of these pattern should be described in pathological reports. This information could be useful in expecting patients' prognosis and providing proper post-operative treatments.

Nomogram for the Preoperative Prediction of the Macrotrabecular-Massive Subtype of Hepatocellular Carcinoma

Background

The macrotrabecular-massive subtype of hepatocellular carcinoma (MTM-HCC) is an aggressive histological type and results in poor prognosis. We developed a nomogram model based on laboratory results to predict the presence of MTM-HCC.

Methods

A total of 357 HCC patients who underwent radical surgery between January 2015 and December 2020 at Ningbo Medical Center Lihuili Hospital were grouped according to histological type. After propensity score matching (PSM), 267 patients were divided into MTM-HCC (n = 76) and non-MTM-HCC (n = 191) groups. A LASSO regression analysis model was used to select predictive factors. Finally, a nomogram for predicting the presence of MTM-HCC was established. Decision curve analysis (DCA) was conducted to determine the clinical usefulness of the nomogram model by quantifying the net benefits along with the increase in threshold probabilities.

Results

The 1-, 3-, and 5-year disease-free survival (DFS) and overall survival (OS) rates for MTM-HCC were 60.0%, 36.0%, 32.4% and 92.1%, 68.7%, 52.2%, respectively. Survival analysis indicated that the probabilities of achieving DFS and OS were significantly worse in the MTM-HCC group than in the non-MTM-HCC group (P < 0.05). The nomogram model that included AST levels, PT and AFP levels achieved a better C-index of 0.723 (95% CI: 0.659-0.787). DCA revealed that the nomogram model could lead to net benefits and exhibited a wider range of threshold probabilities in the prediction of MTM-HCC.

Conclusion

The nomogram model included AST, PT and AFP could achieve an optimal performance in the preoperative prediction of MTM-HCC.

Macrotrabecular-Massive Hepatocellular Carcinoma: Light and Shadow in Current Knowledge

The subject of this narrative review is macrotrabecular-massive hepatocellular carcinoma (MTM‐HCC). Despite their rarity, these tumours are of general interest because of their epidemiological and clinical features and for representing a distinct model of the interaction between the angiogenetic system and neoplastic cells. The MTM‐HCC subtype is associated with various adverse biological and pathological parameters (the Alfa-foetoprotein (AFP) serum level, tumour size, vascular invasion, and satellite nodules) and is a key determinant of patient prognosis, with a strong and independent predictive value for early and overall tumour recurrence. Gene expression profiling has demonstrated that angiogenesis activation is a hallmark feature of MTM-HCC, with overexpression of both angiopoietin 2 (ANGPT2) and vascular endothelial growth factor A (VEGFA).

Variant Hepatocellular Carcinoma Subtypes According to the 2019 WHO Classification: An Imaging-Focused Review

The 2019 5th edition of the WHO Classification of Digestive System Tumors estimates that up to 35% of hepatocellular carcinomas (HCCs) can be classified as one of eight subtypes defined by molecular characteristics: steatohepatitic, clear cell, macrotrabecular massive, scirrhous, chromophobe, fibrolamellar, neutrophil-rich, and lymphocyte-rich HCC. Due to their distinct cellular and architectural characteristics, these subtypes may not display the classic MRI features of HCC of arterial phase hyperenhancement (APHE) and washout appearance, creating challenges in noninvasively diagnosing such lesions as HCC. Moreover, certain subtypes with atypical imaging features have a worse prognosis than other HCCs. A range of distinguishing imaging features may help raise suspicion that a liver lesion represents one of these HCC subtypes. In this review, we describe the MRI features that have been reported in association with various HCC subtypes according to the 2019 WHO classification, with attention to current understanding of these subtypes' pathologic and molecular bases and relevance to clinical practice. Imaging findings that differentiate the subtypes from benign liver lesions and non-HCC malignancies are highlighted. Familiarity with these subtypes and their imaging features may allow the radiologist to suggest their presence, though histologic analysis remains needed to establish the diagnosis.

Tumor Size, Not Small Vessel Invasion, Predicts Survival in Patients With Hepatocellular Carcinoma

OBJECTIVES

The 8th edition American Joint Committee on Cancer (AJCC) staging system for hepatocellular carcinoma (HCC) has been criticized for failing to stratify patients. We aimed to reassess and modify the tumor staging criteria for HCC.

METHODS

Three independent study cohorts were collected and analyzed.

RESULTS

The initial cohort consists of 103 patients with HCC. By Kaplan-Meier survival analysis, the 8th edition failed to distinguish between T1b and T2. Only tumor size and large vessel invasion, but not small vessel invasion or other histopathologic parameters, predicted HCC survival. We modified the T staging criteria by eliminating small vessel invasion while emphasizing tumor size in the middle categories (T2 and T3), which achieved more even distribution of cases and significantly improved risk stratifications (P < .001). This modification was then validated in a cohort of 250 consecutive patients from Mount Sinai Hospital and an online Surveillance, Epidemiology, and End Results data set comprising 9,685 patients, which showed similar results. Small vessel invasion was not an independent prognostic factor in either validation cohort.

CONCLUSIONS

Our study showed that tumor size, but not small vessel invasion, predicts survival in patients with HCC. We suggest incorporating our modified T staging criteria in future AJCC revisions.

Hepatocellular Carcinoma: Does the Background Liver With or Without Cirrhosis Matter?

OBJECTIVES

The pathologic differences between hepatocellular carcinoma (HCC) arising in noncirrhotic and cirrhotic livers have not been well studied.

METHODS

We performed a retrospective analysis of 378 HCC cases (95 in noncirrhotic, 283 in cirrhotic livers) from pathology archives (2010-2017).

RESULTS

Patients without cirrhosis were more likely to have hepatitis B (13.68% vs 2.83%, P < .001) or no known liver disease (30.53% vs 4.24%, P < .001), while hepatitis C was more common in patients with cirrhosis (65.72% vs 30.53%, P < .001). HCCs in noncirrhotic livers were larger in size (P < .001); were more likely to have a macrotrabecular histologic pattern (13.68% vs 4.95%, P < .01); were more likely to have fibrolamellar (3.16% vs 0%, P = .02), macrotrabecular-massive (13.68% vs 6.01%, P = .03), and clear cell (16.84% vs 6.71%, P < .01) subtypes; have a higher histologic grade (P < .01); be anaplastic tumor cells (P < .001); have a higher rate of vascular invasion (P < .01); and have a higher tumor stage (P = .04).

CONCLUSIONS

The findings indicate that HCCs in noncirrhotic livers demonstrate a larger tumor size; have a more macrotrabecular histologic pattern; have fibrolamellar, macrotrabecular-massive, and clear cell subtypes; have a higher tumor grade and stage; have a higher rate of vascular invasion; and have more anaplastic tumor cells compared with cirrhotic livers. Further studies to explore different pathways that promote oncogenesis in noncirrhotic livers are needed to better understand the pathogenesis of HCC.

Imaging features of histological subtypes of hepatocellular carcinoma: Implication for LI-RADS

Background & Aims

The histopathological subtypes of hepatocellular carcinoma (HCC) are associated with distinct clinical features and prognoses. This study aims to report Liver Imaging Reporting and Data System (LI-RADS)-defined imaging features of different HCC subtypes in a cohort of resected tumours and to assess the influence of HCC subtypes on computed tomography (CT)/magnetic resonance imaging (MRI) LI-RADS categorisation in the subgroup of high-risk patients.

Methods

This retrospective institutional review board-approved study included patients with resected HCCs and available histopathological classification. Three radiologists independently reviewed preoperative CT and MRI exams. The readers evaluated the presence of imaging features according to LI-RADS v2018 definitions and provided a LI-RADS category in patients at high risk of HCC. Differences in LI-RADS features and categorisations were assessed for not otherwise specified (NOS-HCC), steatohepatitic (SH-HCC), and macrotrabecular-massive (MTM-HCC) types of HCCs.

Results

Two hundred and seventy-seven patients (median age 64.0 years, 215 [77.6%] men) were analysed, which involved 295 HCCs. There were 197 (66.7%) NOS-HCCs, 62 (21.0%) SH-HCCs, 23 (7.8%) MTM-HCCs, and 13 (4.5%) other rare subtypes. The following features were more frequent in MTM-HCC: elevated α-foetoprotein serum levels (p <0.001), tumour-in-vein (p <0.001 on CT, p ≤0.052 on MRI), presence of at least 1 LR-M feature (p ≤0.010 on CT), infiltrative appearance (p ≤0.032 on CT), necrosis or severe ischaemia (p ≤0.038 on CT), and larger size (p ≤0.006 on CT, p ≤0.011 on MRI). SH-HCC was associated with fat in mass (p <0.001 on CT, p ≤0.002 on MRI). The distribution of the LI-RADS major features and categories in high-risk patients did not significantly differ among the 3 main HCC subtypes.

Conclusions

The distribution of LI-RADS major features and categories is not different among the HCC subtypes. Nevertheless, careful analysis of tumour-in-vein, LR-M, and ancillary features as well as clinico-biological data can provide information for the non-invasive diagnosis of HCC subtypes.

Lay summary

In high-risk patients, the overall distribution of LI-RADS major features and categories is not different among the histological subtypes of hepatocellular carcinoma, but tumour-in-vein, presence of LR-M features, and ancillary features can provide information for the non-invasive diagnosis of hepatocellular carcinoma subtypes.

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The distribution of the major features and categories of LI-RADS is not different among the HCC histological subtypes.

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MTM-HCC was associated with TIV, ≥1 LR-M feature, infiltrative appearance, necrosis or severe ischaemia, and larger size.

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Steatohepatitis-related HCC was associated with fat in mass on CT and on MRI.

Preoperative CT for Characterization of Aggressive Macrotrabecular-Massive Subtype and Vessels That Encapsulate Tumor Clusters Pattern in Hepatocellular Carcinoma

Background Macrotrabecular-massive (MTM) subtype and vessels encapsulating tumor clusters (VETC) pattern of hepatocellular carcinoma (HCC) are associated with unfavorable prognosis. Purpose To estimate the potential of preoperative CT in the prediction of MTM subtype and VETC pattern. Materials and Methods Patients who underwent surgical resection or liver transplant and preoperative CT for HCC between January 2015 and June 2018 were retrospectively included in the primary cohort. CT imaging features were evaluated by two radiologists. Predictors associated with the MTM subtype or VETC pattern were determined by using logistic regression analyses and the performance was tested in a validation cohort. Prognostic factors associated with early recurrence after surgical resection were identified by using Cox regression analyses. Results The primary cohort included 170 patients (median age, 55 years; interquartile range, 48-63 years; 152 men). Serum α-fetoprotein level higher than 100 ng/mL (odds ratio [OR], 4.3; 95% CI: 2.1, 9.2; P < .001), intratumor necrosis (OR, 5.2; 95% CI: 2.5, 11.0; P < .001), and intratumor hemorrhage (OR, 5.4; 95% CI: 1.3, 23.3; P = .02) were independent predictors for MTM subtype, whereas tumor size greater than 5 cm (OR, 3.8; 95% CI: 1.7, 8.1; P = .001) and intratumor necrosis (OR, 2.1; 95% CI: 1.0, 4.4; P = .045) were independent predictors for VETC pattern. These features were used for the construction of ANH and SN scores (where A is α-fetoprotein level, N is necrosis, H is hemorrhage, and S is size), respectively, which showed comparable prediction performance in the primary and validation cohorts. Preoperative high ANH and high SN phenotype (hazard ratio, 1.9; 95% CI: 1.2, 3.0; P = .01) was independently associated with early recurrence after surgical resection. Conclusion Preoperative CT features could be used for the characterization of macrotrabecular-massive subtype and vessels that encapsulate tumor clusters pattern and were of prognostic significance for early recurrence in patients with hepatocellular carcinoma. Online supplemental material is available for this article. See also the editorial by Yoon and Kim in this issue. Published under a CC BY 4.0 license.

Update on Hepatocellular Carcinoma: a Brief Review from Pathologist Standpoint

Hepatocellular carcinoma is one of the most common cancers and an important health problem all over the world. Its prognosis is poor. For better patient care, early diagnosis is essential. Although new imaging techniques have a big impact on hepatocellular carcinoma diagnosis, histopathological examination is still the gold standard for precise diagnosis. Histopathological evaluation gives exact diagnosis in the meaning of tumor size, histological subtypes, grading, and differential diagnosis from metastasis and other tumors. Immunohistochemistry as a part of diagnostic histopathological technique plays an important role in routine practice. Immunohistochemistry is useful for confirming of hepatocytic origin, supporting hepatocellular malignancy, and differential diagnosis. It also gives prognostic information. There are growing attempts to classify tumors by their molecular genetic signatures. This is also actual for hepatocellular carcinoma. This mini review focuses on the histopathology of hepatocellular carcinoma including subtypes; differential diagnosis and immunohistochemistry as an ancillary diagnostic tool, updated or added entities, i.e., combined hepatocellular-cholangiocarcinoma; small hepatocellular carcinoma; correlation with molecular studies; and future perspectives.

Can primary hepatocellular carcinoma histomorphology predict extrahepatic metastasis?

Studies comparing the histomorphologic features and phenotypic heterogeneity between primary and its corresponding metastatic hepatocellular carcinoma (HCC) are lacking. The aim of this study was to assess and compare the histomorphologic features and heterogeneity between primary and metastatic HCC. A total of 39 cases with both primary and metastatic tissues were identified from pathology archives (2000-2019). The common sites of metastasis included lung (28.21%), abdominal cavity (25.64%), lymph nodes (20.51%), bone (17.95%), soft tissue (15.38%), and adrenal gland (10.26%). Both the primary and metastatic tumors showed heterogeneity in intratumoral histologic patterns (87.18% and 76.92%, respectively). The most common histologic pattern was solid in both primary (61.54%) and metastases (56.41%), followed by macrotrabecular in primary (17.95%) and metastases (10.26%). Among HCC-subtypes, macrotrabecular-massive HCC was the most common subtype in both primary and metastases (28.21% each). Primary tumors in noncirrhotic livers were more likely to have larger size and microvascular invasion than those in cirrhotic livers. The histomorphology (histologic pattern, subtype, and grade) between the primary and metastases was discordant in about 50% cases (48.72%, 48.72%, and 51.28%, respectively). Our findings exhibit significant intratumoral heterogeneity and histomorphologic discordance between primary and metastatic HCCs. The solid and macrotrabecular histologic patterns and the macrotrabecular-massive subtype were the most common histomorphologic features seen in primary tumors associated with metastasis. Further studies to identify and explore different pathways that promote HCC metastasis and to compare the differences between primary and metastatic tumors on a larger cohort are needed to better understand the pathogenesis of metastasis.

Macrotrabecular-massive hepatocellular carcinoma: imaging identification and prediction based on gadoxetic acid-enhanced magnetic resonance imaging

OBJECTIVES

To identify image features of macrotrabecular-massive (MTM) hepatocellular carcinoma (HCC) and to determine its role in predicting MTM-HCC.

METHODS

Patients who underwent preoperative gadoxetic acid-enhanced MRI and with surgery proven HCC were retrospectively included. Imaging features were assessed according to Liver Imaging Reporting and Data System. Quantitative measurements were recorded. Clinical characteristics and imaging findings were compared between MTM-HCCs and non-MTM-HCCs. Predictive factors of MTM-HCC were screened with univariate analyses and then identified with multivariate logistic regression. A regression-based diagnostic model was constructed. ROC analyses were used to determine cutoff values, AUC, and corresponding 95% confidence interval (CI) of findings. The diagnostic performance was validated by 10-fold cross-validation.

RESULTS

One hundred and forty-one patients with 37 MTM-HCCs were included. Multivariate analyses identified high platelet count (≥ 163.5 × 10³/ul, odds ratio = 3.20; 95% CI: 1.29, 7.96; p = 0.012), low tumor-to-liver ADC ratio (≤ 1.05, odds ratio = 3.05; 95% CI, 1.23 - 7.55; p = 0.016), and necrosis or severe ischemia (odds ratio = 11.61; 95% CI, 3.99 - 33.76, p < 0.001) as independent predictors of MTM-HCC. Necrosis or severe ischemia alone helped identify 86% MTM-HCCs with a specificity of 66%. The average AUCs were 0.81 (95% CI: 0.71, 0.90) for the regression-based diagnostic model, with a sensitivity of 57% and specificity of 92%.

CONCLUSIONS

Necrosis or severe ischemia was a sensitive imaging feature of MTM-HCC. Noninvasive prediction of this subtype can be achieved with good accuracy and excellent specificity when findings were combined.

KEY POINTS

• The macrotrabecular-massive (MTM) hepatocellular carcinoma (HCC) represents an aggressive subtype of HCC and is associated with poor prognosis. • Imaging features of necrosis or severe ischemia alone helped identify 86% MTM-HCCs with a specificity of 66%. • A regression-based diagnostic model including high platelet count (≥ 163.5 × 10³/ul), low tumor-to-liver ADC ratio (≤ 1.05), and necrosis or severe ischemia can provide noninvasive assessment of MTM-HCC with good accuracy and high specificity.

Gadoxetic acid-enhanced MRI of macrotrabecular-massive hepatocellular carcinoma and its prognostic implications

BACKGROUND & AIMS

Despite the clinical and genetic significance of macrotrabecular-massive hepatocellular carcinoma (MTM-HCC), its characteristics on imaging have not been described. This study aimed to characterise MTM-HCC on gadoxetic acid-enhanced MRI and to evaluate the diagnostic accuracy and prognostic value of these imaging characteristics.

METHODS

We enrolled 3 independent cohorts from 2 tertiary care centres. The 3 cohorts consisted of a total of 476 patients who underwent gadoxetic acid-enhanced MRI and surgical resection for treatment-naïve single HCCs. Independent review of histopathology and MRI by 2 reviewers was performed for each cohort, and inter-reader agreement was evaluated. Based on the result of MRI review in the training cohort (cohort 1), we developed 2 diagnostic criteria for MTM-HCC and evaluated their prognostic significance. The diagnostic performance and prognostic significance were validated in 2 validation cohorts (cohorts 2 and 3).

RESULTS

We developed 2 diagnostic MRI criteria (MRIC) for MTM-HCC: MRIC-1, ≥20% arterial phase hypovascular component; MRIC-2, ≥50% hypovascular component and 2 or more ancillary findings (intratumoural artery, arterial phase peritumoural enhancement, and non-smooth tumour margin). MRIC-1 showed high sensitivity and negative predictive value (88% and 95% in the training cohort, and 88% and 97% in the pooled validation cohorts, respectively), whereas MRIC-2 demonstrated moderate sensitivity and high specificity (47% and 94% in the training cohort, and 46% and 96% in the pooled validation cohorts, respectively). MRIC-2 was an independent poor prognostic factor for overall survival in both training and pooled validation cohorts.

CONCLUSIONS

Using gadoxetic acid-enhanced MRI findings, including an arterial phase hypovascular component, we could stratify the probability of MTM-HCC and non-invasively obtain prognostic information.

LAY SUMMARY

Macrotrabecular-massive hepatocellular carcinoma (MTM-HCC) is a histopathologic subtype of HCC characterised by aggressive biological behaviour and poor prognosis. We developed imaging criteria based on liver MRI that could be used for the non-invasive diagnosis of MTM-HCC. HCCs showing imaging findings of MTM-HCC were associated with poor outcomes after hepatic resection.

An update on subtypes of hepatocellular carcinoma: From morphology to molecular

The morphologic spectrum of hepatocellular carcinoma (HCC) is quite broad. While in about one-third of cases, the neoplasms can be categorized into meaningful subtypes based on morphology, a vast majority of these neoplasms are morphologically heterogeneous. With extensive tumor profiling, data has begun to emerge which can correlate specific morphologic features with underlying molecular signatures. A true morphologic subtype not only has reproducible H & E features, further supported by specific immunohistochemical or molecular signatures, but also has specific clinical implications and prognostic associations. Eight such morphologic subtypes are recognized by the 2019 WHO classification of tumors with a few more additional subtypes described in the literature. The goal of this review is to familiarize the reader with the morphologic subtypes and elaborate on the clinical and molecular associations of these neoplasms.

Hepatocellular carcinoma: making sense of morphological heterogeneity, growth patterns, and subtypes

Hepatocellular carcinomas are not a homogenous group of tumors but have multiple layers of heterogeneity. This heterogeneity has been studied for many years with the goal to individualize care for patients and has led to the identification of numerous hepatocellular carcinoma subtypes, defined by morphology and or molecular methods. This article reviews both gross and histological levels of heterogeneity within hepatocellular carcinoma, with a focus on histological findings, reviewing how different levels of histological heterogeneity are used as building blocks to construct morphological hepatocellular carcinoma subtypes. The current best practice for defining a morphological subtype is outlined. Then, the definition for thirteen distinct hepatocellular carcinoma subtypes is reviewed. For each of these subtypes, unresolved issues regarding their definitions are highlighted, including recommendations for these problematic areas. Finally, three methods for improving the research on hepatocellular carcinoma subtypes are proposed: (1) Use a systemic, rigorous approach for defining hepatocellular carcinoma subtypes (four-point model); (2) Once definitions for a subtype are established, it should be followed in research studies, as this common denominator enhances the ability to compare results between studies; and (3) Studies of subtypes will be more effective when morphological and molecular results are used in synergistic and iterative study designs where the results of one approach are used to refine and sharpen the results of the other. These and related efforts to better understand heterogeneity within hepatocellular carcinoma are the most promising avenue for improving patient care by individualizing patient care.

Hepatocellular Carcinoma: Role of Pathology in the Era of Precision Medicine

Hepatocellular carcinoma (HCC) is a morphologically heterogeneous tumor with variable architectural growth patterns and several distinct histologic subtypes. Large-scale attempts have been made over the past decade to identify targetable genomic alterations in HCC; however, its translation into clinical personalized care remains a challenge to precision oncology. The role of pathology is no longer limited to confirmation of diagnosis when radiologic features are atypical. Pathology is now in a position to predict the underlying molecular alteration, prognosis, and behavior of HCC. This review outlines various aspects of histopathologic diagnosis and role of pathology in cutting-edge diagnostics of HCC.

Fibronodular hepatocellular carcinoma-a new variant of liver cancer: clinical, pathological and radiological correlation

AIMS

To establish and define a new, not previously reported hepatocellular carcinoma (HCC) variant, termed fibronodular HCC (FN-HCC).

METHODS

We retrospectively reviewed 290 HCC cases and identified 29 FN-HCC and 24 scirrhous HCC (SCHCC). Clinical, pathological and radiological features of FN-HCC were reviewed and compared with 30 conventional HCCs (CV-HCC) and SC-HCC.

RESULTS

FN-HCCs were more likely to arise in non-advanced fibrotic livers with lower advanced Barcelona Clinic Liver Cancer (BCLC) stage, had lower rates of progression and longer time to progression and were more likely to be surgically resected compared with CV-HCCs and SC-HCCs. Imaging analysis of FN-HCCs demonstrated higher rates of non-peripheral washout and a new distinct pattern of enhancement which is characterised by the presence of multiple rounded nodules within a lesion embedded in fibrotic-appearing parenchyma.

CONCLUSIONS

FN-HCC may represent a specific variant of HCC with distinct pathological, radiological and clinical features with potential ramifications for outcome.