Figure 1

(A) Papillary RCC composed of fibrovascular fronds covered by cells with pink cytoplasm. Inset shows high magnification of the cells lining the fronds, revealing cytologic nuclear atypia and oncocytic cytoplasm (type II features). (B) Sarcomatoid component of the RCC, with loosely aggregated epithelioid and spindled pleomorphic cells with occasional multinucleation. Accompanying inflammatory cells are present. (C) Tumour thrombus within the renal vein. (D) Fine needle aspiration cytology of the lung lesion, revealing morular, loosely cohesive clusters of abnormal epithelial cells (Diff-Quik). Inset shows a PAP stained finger-like conglomerate of cells with enlarged vesicular nuclei and prominent nucleoli, in keeping with metastatic papillary RCC.