Fig. 2: L1CAM and laminin expression in uveal melanoma liver metastases.

L1CAM expression in HGPs. A Replacement HGP. This field shows scattered nests of melanoma cells positive for L1CAM (red chromogen). seen predominately at the advancing front of the metastasis (M) with extension for some distance into the surrounding liver parenchyma (L). B The melanoma cells infiltrate among hepatocytes along the external surfaces of sinusoidal vascular channels in a non-infiltrative pattern. Note membranous expression of L1CAM. C, D Desmoplastic HGP. Absence of expression of L1CAM. Laminin expression in HGPs. E Replacement HGP. Laminin is strikingly positive in the infiltrative front and is characterized by a “vascular network pattern”, i.e., laminin marks (red chromogen) the basement membrane zone of anastomosing sinusoidal channels that interface with melanoma cells infiltrating the hepatic parenchyma. F This field shows scattered melanoma cells present along vascular channels positive for laminin (red chromogen) seen predominately at the advancing front of the metastasis. G, H Desmoplastic HGP. The prototypic laminin vascular network pattern is not seen. I Replacement HGP. High melanin index and general absence of L1CAM positivity in melanoma cells (arrows) at the advancing front. J Replacement HGP. Increasing L1CAM expression in melanoma cells (arrows) infiltrating the hepatic parenchyma (L) at the invasive front. These tumor cells exhibit diminished or absent melanin.