Malignant testicular unclassified sex cord stromal tumor: a case report.

Background: Most testicular tumors are germ cell tumors; sex cord stromal tumors are infrequent, accounting for only 3-5% of testicular tumors. Unclassified sex cord stromal tumors are extremely rare. Generally, 10% of sex cord stromal tumors are malignant. We report a case of malignant unclassified sex cord stromal tumor with retroperitoneal lymph node metastasis at first visit and a corresponding literature review.
Case Presentation: A 72-year-old Japanese man visited our department primarily for indolent right scrotum enlargement in September 2020. Blood biochemistry examination, urinalysis, and tumor markers (alpha-fetoprotein, human chorionic gonadotropin, and lactate dehydrogenase) showed no abnormal findings. Contrast-enhanced computed tomography showed enlarged para-aortic lymph node (18 × 16 and 10 × 10 ²  mm); a 50 × 45 ²  mm mass with uneven contents was found in the right testicle. The patient underwent inguinal orchiectomy in September 2020. As per immunohistochemistry, the tumor cells were diffusely positive for SF-1 and Ki-67, partially positive for inhibin, and negative for CAM5.2, CK7, CK20, C-KIT, CD30, LCA, GATA-3, TTF-1, and PAX8. Calretinin was expressed in approximately 5% of tumor cells; thus, sex cord/gonadal stroma components were considered to be involved. The final pathological diagnosis was unclassified malignant sex cord stromal tumor. The patient was diagnosed with pT1, N1, M0, S0, and tumor-node-metastasis stage IIA disease. The patient received postoperative chemotherapy with four courses of etoposide and cisplatin therapy from November 2020. Post-chemotherapeutic computed tomography showed new metastatic lesions including lung, liver, pancreas, and para-aortic lymphadenopathy, which increased in size. Disease progression was observed. Cancer genome research was performed using the OncoGuide National Cancer Center oncopanel system; however, no gene mutation for which the drug could be expected to be effective was found. The patient opted for best supportive care at a nearby hospital and died from cancer progression in January 2022.
Conclusion: We encountered a case of malignant testicular unclassified sex cord stromal tumor pathologically diagnosed as testicular tumor with retroperitoneal lymph node metastasis in a patient who underwent inguinal orchiectomy. Future data collection is necessary to establish multimodality therapy for malignant testicular unclassified sex cord stromal tumor.
(© 2022. The Author(s).)