Hepatocellular Carcinoma Variants: Radiologic-Pathologic Correlation

Abstract

W7poorer prognosis than classic HCC, whereas fibrolamellar HCC shows better prognosis and sclerosing HCC shows prognosis similar to classic HCC [5][6][7]. Radiologically, these variants do not share imaging characteristics typical of HCC.The diagnosis of HCC larger than 2 cm can be made without biopsy if a mass in a cirrhotic liver shows the typical features of HCC on contrast-enhanced CT or MRI and the α-fetoprotein level is greater than 200 ng/mL [8]. In the case of HCC with atypical imaging features, however, this guideline cannot be applied. Therefore, recognizing these variants and their imaging features has clinical consequences, even though a preoperative biopsy is still needed because these variants cannot be completely differentiated from other tumors by imaging only.In this article, we collectively review and illustrate the radiologic findings for variant types of HCC and correlate these findings with pathologic analyses. HCC, Predominantly Clear Cell TypeCytoplasmic fat is frequently present in well-differentiated HCC and is abundant in approximately 10% of cases. A large amount of cytoplasmic fat or glycogen can cause the cytoplasm to appear white in routine pathologic sections, producing a "clear cell" appearance. On microscopy, 19.6% of HCCs have been reported to have cytoplasmic fat. On imaging, however, only 1.6% of cases have been reported to show a cytoplasmic fat component [9]. HCCs with a clear cell appearance frequently show increased echogenicity on sonography and decreased attenuation on is the most common form of primary hepatic tumor and its incidence has increased in recent years. The risk factors for HCC are well established and include viral hepatitis, alcoholic liver cirrhosis, and exposure to hepatotoxins. The typical sonographic and unenhanced CT findings of HCC show a well-circumscribed hypoechoic or hypoattenuated mass with or without the hypoechoic rim of a tumor capsule. MRI typically shows that HCC is hyperintense relative to the liver on T2-weighted images and hypointense on T1-weighted images. On dynamic CT and MRI, HCC shows early enhancement in the arterial phase and contrast medium washout in the equilibrium phase. Equilibrium phase CT and MRI could show a thin rim-enhancing tumor capsule with variable incidence, ranging from 10% to 80.7% of the cases, depending on the series [1]. G a s t r oi nt e s t i n a l I m ag i ng • Pic t o r i a l E s s ayAlthough the prevalence is variable depending on the series, hemorrhage or calcification (~ 5%), central scar (~ 3%), or gross fat (~ 1.6%) may be seen within the HCC tumor [2]. HCC in noncirrhotic patients usually manifests as either a large solitary mass or a dominant mass with small satellite nodules that more frequently shows necrosis and central scar formation than HCC in cirrhotic patients [3].

Noninvasive diagnosis of hepatocellular carcinoma on gadoxetic acid-enhanced MRI: can hypointensity on the hepatobiliary phase be used as an alternative to washout?

“…None of the benign lesions showed hypointensity on the PVP. As cHCC-CC is histologically composed of elements from both entities, its vascular pattern on contrast-enhanced imaging depends on the proportion of the tumour components [45,46]. Therefore, an HCC-dominant tumour can show arterial hypervascularity and washout on a later phase mimicking an HCC, leading to a false positive diagnosis even with CT or ECCM-enhanced MRI [47,48].…”

Rare hepatic malignant tumors: dynamic CT, MRI, and clinicopathologic features: with analysis of 54 cases and review of the literature

“…However, tumors with clear cells ranging from 90% to 100% are extremely rare [61]. Most studies are diagnosed PCCCL when the proportion of clear cells was >50% [58,62,63]. The rates of hepatitis B virus infection and capsule formation were higher in PCCCL patients than in those with HCC.…”

Quantitative morphometric analysis of hepatocellular carcinoma: programmed algorithm development and preliminary application

“…Fourth, the extent of the tumor to the liver surface, vasculature, or other nonparenchymal tissue (e.g., gallbladder) may affect the tumor boundary through a tendency to assume the natural smoother contour of such an anatomic structure. Fifth, our algorithm focuses on external contour and ignores internal characteristics, such as hemorrhage, calcification, central scar, or gross fat, which may be features of different HCC pathological subtypes (34). Sixth, our two-dimensional shape analysis attempted to capture the representative contour of a three-dimensional (3D) object at its maximum transverse diameter.…”