Photomicrograph of liver metastases. A). Liver metastasis showing almost complete necrosis within a fibrous capsule. Cells adjacent to the capsule contain a brown pigment. B). The pigment disappears in melanin bleach preparation. C). Very few cells stained positive for S100. In this section, only 1 positive cell was observed, staining a homogeneous dark brown color compared with the dotted granular brown appearance of neighboring cells. D). The majority of the pericapsular cells containing melanin stained positive for CD68, indicating that they are macrophages.