Pseudocapsule of hepatocellular carcinoma: CT and US versus pathologic correlation

ABSTRACT

The encapsulated hepatocellular (HCC) is a pathologic subtype of HCC. It is a well defined tumor that tends to grow slowly, and has a better prognosis than any other gross forms of HCC. Twenty surgically resected HCC were evaluated retropectively to correlate the thickness of pseudocapsules in pathology with those in computed tomography and ultrasound. At a histologic examination, pseudocapsules of seven cases were composed of two layers, an inner compact fibrous zone and outer loose fibrous zone interlaced with compressed liver parenchyma containing small vessels and newly formed bile ducts. Sonographic thickness and pathologic measurements of pseudocapsule relatively well correlated, but the former slightly overestimated the thickness of pathologic pseudocapsule (r=0.825, y=2.56x-1.23, P<0.05). On the other hand, thickness in CT and pathologic measurement did not correlate well. Thirteen cases showed one layer of pseudocapsule in which two cases were composed of thin layer of compact fibrosis and eleven cases composed of loose fibrosis. There were poor correlations in this group between thickness of pseudocapsules in pathology and those in images. Image overtly overestimated the thickness of the pseudocapsules in pathology. In conclusion, radiologic pseudocapsule of HCC may represent the compressed liver parenchyma as well as the fibrous pseudocapsule.