Light micrograph of a renal oncocytoma. An oncocytoma is a benign kidney tumour. It is composed of cells that have abundant oncocytic (pink) cytoplasm, and has nuclei (blue dots) that are roughly round and uniform. Thin vessels (thin pink lines) wrap around groups of the oncocytoma cells. Haematoxylin and eosin stained tissue section. Magnification: 200x when printed at 10cm.