HISTOLOGY
Right nephrectomy
Right kidney with proximal ureter surrounded by perinephric fat (23 x 11 x 11 cm, 1140 g). The adrenal gland is also noted sitting on the perinephric fat, gold/yellow in colour. No obvious tumour masses are identified within the adrenal gland. On sectioning the kidney, there is a 11 x 11 x 8 cm orange/yellow well circumscribed tumour in the upper pole. The tumour displays areas of necrosis and foci of haemorrhage. Large 5 cm haematoma within the tumour. The remaining renal parenchyma appears hypertrophied with a dilated pelvicalyceal system and ureter, no other focal lesions.
Left renal core biopsy
Sections show epithelial neoplasm composed of a mixture of clear cells and cells with abundant eosinophilic cytoplasm. Compact crowded nests with large polygonal cells and occasional prominence of cell membranes. Granular eosinophilic cytoplasm is prominent in approximately 70% of cells with no convincing perinuclear halos. The nuclei are rounded without rasinoid forms or binucleation. Immunohistochemistry: PAX-2 positive, cytokeratin 7 positive (but not diffusely strong more suggestive of choromophobic carcinoma); negative RCC markers (vimentin, RCC antigen, CD10. This lesion (similar to the lesion in the right kidney) is difficult to accurately classify as either chromophobe carcinoma or oncocytoma because it shows overlapping morphological and immunohistochemical findings. It is best regarded as a hybrid tumour.