Fig. 1

Well-differentiated neuroendocrine tumor associated with prepubertal-type teratoma. a Small well-differentiated neuroendocrine tumor (arrow) surrounded by dilated glands and smooth muscle adjacent to uninvolved tubules seminiferous. b High power view of the glands lined by cytologically bland ciliated epithelium. c, d The well-differentiated neuroendocrine tumor is composed of solid islands of cells with uniform bland nuclei separated by a fibrous stroma. e Labeling for chromogranin is diffuse and strong in the well-differentiated neuroendocrine tumor. f Uninvolved seminiferous tubules with only focal tubular atrophy adjacent to the tumor, but otherwise show active spermatogenesis without germ cell neoplasia in situ