Figure 2.

Histologic (H&E) findings of primary carcinoid tumor arising within mature teratoma of the kidney. (A) Teratomatous components of urothelium and mucinous columnar epithelium. Original magnification ×100. (B) Teratomatous components of urothelium and mucinous columnar epithelium. Original magnification ×400. (C) Carcinoid tumor underneath and closely apposed to the epithelial lining of the teratomatous cysts. Original magnification ×100. (D) Carcinoid tumor invading teratomatous mature bone. Original magnification ×100. (E) Carcinoid tumor showing the classical architectural pattern of trabecular and anastomosing ribbon-like nests. Original magnification ×200. (F) Carcinoid tumor showing the classic cytologic features of monotonous small cells with peripheral palisading and focal rosette-like arrangement, and "salt-and-pepper" chromatin pattern. Original magnification ×400.