Slide 1.21
The cells composing a pheochromocytoma are similar to the adrenal medulla chromaffin cells. They are large, polygonal cells with abundant, finely granular cytoplasm due to catecholamines granules content. This tumor frequently displays nuclear pleomorphism. Capsular and vascular invasion and mitotic figures can also be seen, but they do not predict malignant behaviour. A diagnosis of malignant pheochromocytoma is based exclusively on the presence of metastases.