Absence of Low Internal Echoes as an Indicator of Non-aggressive Components in Hepatocellular Carcinomas: A Case Report.

The differentiation degree of hepatocellular carcinomas (HCCs) well correlates with their aggressiveness. However, except for tumor size and mass border clarity, no preoperative images have been clarified to easily and accurately predict the differentiation degree of HCCs.A 74-year-old man with a liver mass was referred to our hospital. Computed tomography (CT) showed a round and well-circumscribed mass with a slightly lower Hounsfield Unit value than that of the surrounding liver parenchyma, and showed weak early enhancement and a washout pattern. Ultrasound showed an oval mass with very high internal echoes and enhanced posterior echoes. Magnetic resonance imaging of the mass showed slightly low signals on T1-weighted images, high intensity with focal low signals on fat-suppressed T2-weighted images, and weak early enhancement on subtraction images. Due to the elevated serum Protein Induced by Vitamin K Absence or Antagonist-II (PIVKA-II) level in addition to these image findings, the patient underwent a laparoscopic partial hepatectomy under the tentative diagnosis of HCC. Postoperative pathological study showed an oval mass, 65 mm in size, mainly composed of moderately differentiated HCC cells growing in a cord-like fashion with numerous pseudoglandular structures, a thin fibrous capsule encompassing the tumor, and focal areas of well-differentiated HCC cells growing in a thin-trabecular fashion with numerous lipid droplets. Clinicians should note that the absence of low internal echoes indicates the absence of aggressive components even in large HCCs.