Mixed epithelial stromal tumor of the kidney

Abstract

In recent years, a rare distinctive kidney tumor composed of a mixture of stroma and epithelium with solid and cystic architecture has been recognized, which has to be distinguished from other renal neoplasms. The term mixed epithelial and stromal tumor was first introduced by Michal and Syrucek in 1998.[1] The vast majority of cases show a benign course without tumor recurrence. Here, we present a case of this entity, found incidentally.

Keywords: Adult type of mesoblastic nephroma; mixed epithelial stromal tumor.

Figure 1

(a) Right Retrograde Pyelogram showing a filling defect in the renal pelvis causing hydronephrosis of the kidney; (b) contrast-enhanced computed tomography showing a large tumor filling the renal pelvis causing hydronephrosis of the right kidney

Figure 2

(a) Gross photograph of the tumor showing predominantly solid area with papillary excrescences; and (b) cystic areas; (c) low magnification photograph of the tumor showing both epithelial and mesenchymal components (HandE, ×40); (d) higher magnification shows cuboidal cell lining of epithelium with underlying ovarian like stroma (HandE, ×400); (e) intense reactivity for pancytokeratin in epithelial lining of tumor cells (HRP Polymer Cytokeratin, ×100); (f) vimentin reactivity in ovarian-like mesenchymal stroma (HRP Polymer Vimentin, ×100); (g) Estrogen Receptor shows nuclear positivity in spindle cells (IHC, ×400); (h) Progesterone Receptor shows nuclear positivity in spindle cells (IHC, ×400)