Hepatocellular Carcinoma With Atypical Imaging Features: Review of the Morphologic Hepatocellular Carcinoma Subtypes With Radiology‐Pathology Correlation

Abstract

Hepatocellular carcinoma (HCC) is the fastest growing cause of cancer death in the United States with the incidence rate more than doubling in 20 years. HCC is unique since a noninvasive diagnosis can be achieved with imaging alone when specific clinical criteria and imaging characteristics are met, obviating the need for tissue sampling. However, HCC is a highly heterogeneous neoplasm. Atypical HCC subtypes vary significantly in their morphology, which can be attributed to specific histologic and molecular features, and can cause deviations from the classic imaging characteristics. The different morphologic subtypes of HCC frequently present a diagnostic challenge for radiologists and pathologists since their imaging and pathologic features can overlap with those of non-HCC malignancies. Identifying an atypical subtype can have important clinical implications. Liver transplant, albeit a scarce and limited resource, is the optimal treatment for conventional HCC, potentially curing both the tumor and the underlying pre-malignant condition. Some HCC subtypes as well as mimickers are associated with unacceptably high recurrence and poor outcome after transplant, and there remains limited data on the role and prognosis of liver transplantation for treatment of rare HCC subtypes. Other subtypes tend to recur later than classic HCC, potentially requiring a different follow-up scheme. This review will discuss the appearance of different HCC subtypes in relation to their histopathologic features.

Current Imaging Diagnosis of Hepatocellular Carcinoma

“…Recently, Bello et al [ 74 ] brought attention to several HCC subtypes with atypical imaging features and correlated them with their histologic and molecular features; for example, an early peripheral and progressive centripetal enhancement (a pattern similar to ICC) was indicative of the scirrhous subtype. Fowler et al [ 75 ] have also presented distinct morphologic and pathologic subtypes of HCC with different prognostic implications.…”

A preoperative model based on gadobenate-enhanced MRI for predicting microvascular invasion in hepatocellular carcinomas (≤ 5 cm)

“…However, HCC is a highly heterogeneous neoplasm ( 33 ). The atypical enhancement pattern may be attributed to different pathological subtypes ( 34 ). Atypical HCC subtypes vary widely in morphology, which can be attributed to specific histological and molecular features and may lead to atypical imaging features ( 35 ).…”

“…Atypical HCC subtypes vary widely in morphology, which can be attributed to specific histological and molecular features and may lead to atypical imaging features ( 35 ). Previous studies have shown that clear cell HCC lacks the tendency to hyperenhancement in the arterial phase and classic enhancement pattern when the proportion of clear cells was 100% ( 34 , 35 ); the most common enhancement patterns in scirrhous HCC are peripheral, rim-like enhancement and late-phase progressive central enhancement ( 34 , 35 ). In addition, Elevated AFP level has been reported to be independent predictors of MVI, which is in agreement with the present results ( 7 , 15 ).…”

The clinicopathological and prognostic factors of hepatocellular carcinoma: a 10-year tertiary center experience in Egypt

“…However, five clear cell HCC cases exhibited atypical triphasic CT features: three exhibited gradual contrast enhancement during the portal phase and two showed minimal enhancement with maintained hypoattenuation at the arterial and venous phases [42]. Therefore, awareness of the special variants of HCC may have potential clinical implications for the patients' prognosis and may serve as a diagnostic clue for the atypical imaging findings [43].…”