Ultrastructural study of human adrenal pheochromocytoma by open needle biopsy.

Samples from eight cases of human adrenal pheochromocytoma were obtained using open needle biopsy and processed for electron microscopy. The good tissue preservation and the absence of mechanical damage allowed the confirmation of already described features of this differentiated tumor or of new findings. The presence of catecholamine granules in the pericapillar spaces and in the lumen of fenestrated capillaries was documented together with that of amyelinated nerve fibers surrounded by Schwann cells or in close contact with chromaffin cells.