Aim: Emerging evidence suggests a promising role for tumor stromal factors in characterizing patients with various types of malignancies, including hepatocellular carcinoma (HCC). We quantified the amount of collagen and elastin fibers in HCC samples with the aim of clarifying the clinico-patho-radiological significance of fiber deposition in HCC. Methods: We computed the amount of collagen and elastin fibers using digital image analysis of whole-slide images of Elastica van Gieson-stained tissues from 156 surgically resected HCCs. Furthermore, we assessed the correlations between the fiber content of HCC samples and clinical, pathological, and radiological features, including immunohistochemistry-based molecular subtypes and immunosubtypes. Results: The intratumoral area ratio of collagen in HCC tissues (median 3.4%, range 0.1–22.2%) was more than threefold that of elastin (median 0.9%, range 0.1–9.0%); there was a strong positive correlation between the amounts of collagen and elastin. Higher levels of combined collagen and elastin were significantly associated with the confluent multinodular macroscopic tumor type, the absence of a fibrous capsule, intratumoral steatosis, scirrhous tumor stroma, dense inflammatory-cell infiltrates, and the biliary/stem cell markers-positive HCC subtype. The associations of higher collagen levels with radiological findings, including heterogeneous enhancement and persistent enhancement on dynamic computed tomography, were significant. In contrast, the associations of radiological findings with elastin fibers were not significant. Intratumoral fibrous stroma in HCC comprised septum-like and perisinusoidal fibrosis; these two forms represented distinct distribution patterns of fibers and fibroblasts. Conclusion: Quantitative analysis suggested that stromal fiber-rich HCCs likely represent a distinct clinico-patho-radiological entity.
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