Germ Cell Neoplasia in Situ Recognized Incidentally with Complaining of Discomfort in the Right Testis: A Case Report

A 27-year-old man experienced discomfort in his right testis in early September, 2021, and visited the hospital five days later. Physical examination did not detect any abnormalities in the scrotum. However, an ultrasound revealed a tumor in the central part of the right testis, and a Magnetic Resonance Imaging (MRI) showed a tumor 2.7cm in diameter with clear boundaries and a marginally smooth surface. The level of alpha-fetoprotein, human chorionic gonadotropin, human chorionic gonadotropin-β subunit, and lactate dehydrogenase were within normal limits. A Computed Tomography (CT) scan showed no abnormalities. We can't rule out the possibility of malignancy, right radical orchiectomy was performed with a diagnosis of right testicular tumor in mid-September 2021. The macroscopic lesion was 1.5×1.3 cm in size, and no viable tumorous cells were found pathologically. Atypical cells were observed in the seminiferous tubules from the spermatic cord, which were positively stained with immune-histochemical staining CD117 (c-kit), D2-40, and MIB-1 but negatively with alpha-fetoprotein, human chorionic gonadotropin, and human chorionic gonadotropin-β subunit. The pathological diagnosis was germ cell neoplasia in situ, and no continuity was observed between these cells and bleeding necrosis. The patient has been followed up for 1 year and 4 months after surgery, with no recurrence or metastasis observed.