Fig. 1

Examples of gross pathology and histological analysis of pushing (a–c) and infiltrative (d–f) growth patterns in non-otherwise specified (NOS) adenocarcinoma liver metastases in a 54-year-old female patient with metastatic rectal cancer, and a 71-year-old male patient with metastatic rectal cancer, respectively. In the pushing pattern, tumor borders appear well-delineated both on T2-weighted MR images and gross pathology (a, b—arrows), while they are slightly more ill-defined with the infiltrative pattern (d, e—arrows). The difference in the two patterns is clearly observed on histological analysis: the pushing pattern (c) shows liver cells (Li) compressed by the tumor (T) without tumor cells in the hepatic plates. The infiltrative pattern (f) is characterized by the invasion of the liver (Li) parenchyma by tumor cells (T—arrows)