Figure 3.

The tumor contains abundant coarse pigment (A, x 200). The area in the inset box in A is removed from paraffin blocks for ultrastructural analysis and is shown in B. Electron microscopy shows that a tumor cell has large, pleomorphic granules with varying electron density, size and shape, which are identified as neuromelanin (arrow). N, nucleolus; RER, rough endoplasmic reticulum (B, x 6000) (glutaraldehyde-refixed after retrieval from formalin-fixed material).