Fig. 3
a Left kidney bisected. A round, well-circumscribed tumour with central cystic degeneration is present in the lower pole of the kidney. b The tumour is composed of spindle-shaped cells with eosinophilic cytoplasm growing in intersecting fascicles. Haematoxylin and eosin, original magnification × 200. c The nuclei of the tumour cells often have rounded ends (“cigar-shaped” nuclei). Scattered lymphocytes are noted in the background. Significant pleomorphism, tumour necrosis and increased mitotic activity are absent. Haematoxylin and eosin, original magnification × 400. d An immunohistochemical stain for desmin shows strong and diffuse cytoplasmic staining. Original magnification × 200