Volume 54, Issue 6, Pages 1237-1246 (December 2008) Cystic Nephroma and Mixed Epithelial and Stromal Tumour of the Kidney: Opposite Ends of the Spectrum of the Same Entity?  Rodolfo Montironi, Roberta Mazzucchelli, Antonio Lopez-Beltran, Guido Martignoni, Liang Cheng, Francesco Montorsi, Marina Scarpelli  European Urology  Volume 54, Issue 6, Pages 1237-1246 (December 2008) DOI: 10.1016/j.eururo.2007.10.040 Copyright © 2007 European Association of Urology Terms and Conditions

Fig. 1 Macroscopic appearance of a mixed epithelial and stromal tumour. It is composed of multiple cysts and solid areas. The solid component is an off-white firm tissue, reminiscent of leiomyoma. Fig. 2 – Whole-mount section of a cystic nephroma. It is an encapsulated, well-demarcated tumour composed entirely of cysts and thin septa. Fig. 3 – Microscopic appearance of a cystic nephroma. The cyst is lined by flattened hobnail epithelium. The septal stroma consists of fibrous tissue. Fig. 4 – Whole-mount section of a mixed epithelial and stromal tumour. It is a well-demarcated tumour composed of large cysts, microcysts, and tubules and of cellular stroma (see Fig. 5). Fig. 5 – Microscopic appearance of a mixed epithelial and stromal tumour. It includes microcysts and tubules and ovarian-like stroma. Fig. 6 – The epithelial component of the cystic nephroma, similarly to mixed epithelial and stromal tumour, is intensely stained with antibodies against cytokeratins AE1/AE3. Fig. 7 – The stromal cells in both cystic nephroma and mixed epithelial and stromal tumour are intensely positive for vimentin. Fig. 8 – The stromal cells in both cystic nephroma and mixed epithelial and stromal tumour are positive for smooth muscle actin. Fig. 9 – The epithelial cells are focally positive for calretinin. Scattered positive cells are seen in the stroma. European Urology 2008 54, 1237-1246DOI: (10.1016/j.eururo.2007.10.040) Copyright © 2007 European Association of Urology Terms and Conditions

Fig. 10 Estrogen receptors are seen in the nuclei of the stromal cells of both cystic nephromas and mixed epithelial and stromal tumours. Fig. 11 – Progesterone receptors are seen in the nuclei of the stromal cells of both cystic nephromas and mixed epithelial and stromal tumours. The expression of progesterone receptor is more extensive and is present in more cells than estrogen receptor (see Fig. 10 for comparison). Fig. 12 – Mixed epithelial and stromal tumour with stroma composed of smooth muscle cells indistinguishable from a leiomyoma. Fig. 13 – Same case as in Fig. 12. The stromal cells are positive for desmin. Fig. 14 – Same case as in Fig. 12. The stromal cells are positive for caldesmon. Fig. 15 – Mixed epithelial and stromal tumour in which the epithelial component shows areas of solid growth with intracytoplasmic small lumina. Fig. 16 – Higher magnification of the same cases as in Fig. 15. The nuclei are enlarged and slightly irregular, with recognisable nucleoli. Fig. 17 – Progesterone receptors are seen in the nuclei of the epithelial cells of a mixed epithelial and stromal tumour. Very few positive nuclei are seen in the stroma (Insert shows epithelial cells with estrogen receptors; same case as in Figs. 15 and 16). Fig. 18 – Whole-mount section of a mixed epithelial and stromal tumour. The stroma is composed of dense collagen and is calcified (Insert shows epithelial lining with vacuolated cytoplasm). European Urology 2008 54, 1237-1246DOI: (10.1016/j.eururo.2007.10.040) Copyright © 2007 European Association of Urology Terms and Conditions