Collagen immunostains can distinguish capsular fibrous tissue from septal fibrosis and may help stage liver fibrosis.

Core-needle biopsy remains essential for diagnosis of cirrhosis; however, evaluation of fibrosis in such biopsies is often challenging due to the fragmented nature of cirrhotic liver specimens. It is also common to see portions of liver capsules present in the biopsy which adds to the diagnostic challenge. The distinction between capsular/subcapsular fibrous tissue and septal fibrosis is critical to avoid potential overstaging of liver fibrosis. We compared the differential immunostaining in liver capsular and septal areas for collagens III, IV, V, VI, vitronectin, laminin, Orcein, and Trichrome in 15 whole sections of explanted cirrhotic livers and 5 simulated liver biopsies. Collagens III, IV, V, VI, Trichrome, and Orcein show distinct staining patterns in capsular fibrous tissue and septal fibrosis. Collagen IV shows strong diffuse septal staining and consistently weak to negative capsular staining. Collagens III and VI stain similar to IV for septal fibrosis, whereas collagen V, Trichrome, and Orcein show strong staining in both areas. Collagen IV, possibly with III or VI in addition to the routine Trichrome and hematoxylin and eosin stain, is useful in differentiating capsular fibrous tissue from septal fibrosis on challenging and fragmented liver biopsies.