Adenomatoid tumor of the testis in a patient with history of cryptorchidism, male breast cancer, and thymic B2 thymoma: a case report and literature review.

Background: Adenomatoid tumor is a rare benign neoplasm of mesothelial origin, most commonly arising in the epididymis, vas deferens, and tunica vaginalis; primary occurrence in the testis is extremely rare. Cryptorchidism is recognized as a risk factor for testicular germ cell tumors, but its association with adenomatoid tumors remains hypothetical, as there is limited mechanistic evidence directly linking cryptorchidism to mesothelial tumorigenesis in the testis. Moreover, multiple primary malignancies may be related to impaired immune surveillance or genetic susceptibility, though these mechanisms require further validation. This case report aims to present a patient with a testicular adenomatoid tumor in the context of previous cryptorchidism, male breast cancer, and thymic B2 thymoma, and to discuss the possible mechanisms underlying multiple primary tumors and the role of intraoperative pathology in testis-sparing decisions. Case summary: A 58-year-old man with a history of right-sided cryptorchidism treated by orchiopexy, with normal subsequent fertility, was found on magnetic resonance imaging (MRI) to have a solid nodule within the right testis suggestive of a probably benign testicular neoplasm. Serum markers of testicular malignancy were normal. Given his age, history of cryptorchidism, and multiple prior tumors, and after being informed of testis-sparing alternatives, the patient and his family requested a right radical orchiectomy. Pathology confirmed a right testicular adenomatoid tumor. The procedure was uneventful, recovery was good, and a two-year follow-up was unremarkable. Conclusion: For testicular lesions in patients with a history of cryptorchidism, adenomatoid tumor should be included in the differential diagnosis, particularly when imaging findings and serum tumor markers suggest a benign lesion. In younger patients or patients desiring fertility preservation, intraoperative frozen section combined with rapid immunohistochemistry may improve the accuracy of differentiating benign from malignant lesions and reduce unnecessary radical orchiectomy, although diagnostic uncertainty and institutional availability should be considered. The coexistence of multiple primary tumors suggests possible immune or genetic susceptibility mechanisms. Thymoma-related immune dysregulation is better supported for malignant tumors, whereas genetic explanations remain speculative without molecular testing. Larger multicenter studies are needed to further evaluate these observations.