It is challenging to separate peritumoral fibrosis from fibrosis due to chronic liver disease in mass-directed liver biopsies. We evaluated the distance that peritumoral fibrosis extends from metastatic colorectal adenocarcinoma in liver.
Peritumoral and distant uninvolved liver trichrome stains from 25 cases were analyzed using digital image analysis. Fibrosis was quantitated at concentric intervals from each tumor and in uninvolved liver.
There was a 3.9 fold (range 0.9-18.6) median increase in fibrosis in the first 0.5 mm of peritumoral liver compared to distant liver. Fibrosis levels returned to baseline at median 2.5 mm (interquartile range 1.5-5.0 mm) from tumor.
Fibrosis is markedly increased in peritumoral liver. Fibrosis levels returned to baseline by 5 mm from tumor in approximately 75% of cases. Pathologists should be cautious of fibrosis in mass-directed liver biopsies without at least 5 mm of liver tissue distal to the mass.