[A CASE OF RIGHT TESTICULAR SEMINOMA WITH REGRESSIVE CHANGES PRESENTING AS INGUINAL LYMPH NODE METASTASIS].

A 32-year-old male presented with a growing right inguinal mass. He had a history of right orchiopexy for cryptorchidism at age 8. Radiologic imaging, including CT and MRI, suggested a malignant soft tissue tumor. Needle biopsy confirmed seminoma, leading to referral to our department. Physical examination revealed a 12 cm tender mass in the right inguinal region. The right testis was atrophic, with no palpable intratesticular mass. Ultrasonography showed diffuse microcalcifications within the right testis parenchyma, with a small space-occupying lesion identified within these areas. FDG-PET/CT demonstrated focal abnormal uptake limited to the right inguinal region, suggesting a regressed testicular seminoma. En-bloc resection of the right testis and inguinal mass was performed. Histopathological analysis confirmed metastatic inguinal lymph node involvement secondary to a regressed testicular seminoma (pT1N3M0, stage IIC). Postoperatively, tumor markers normalized, and FDG-PET/CT showed no abnormal uptake. The patient was managed with close surveillance without adjuvant chemotherapy. No recurrence has been seen during the five-year follow-up.In patients with a history of orchiopexy, the inguinal lymph nodes may serve as regional lymph nodes for testicular tumors. Additionally, spontaneous regression of the primary testicular lesion, known as a "burned-out" tumor, should be considered in atypical presentations. This case highlights the importance of comprehensive imaging and histopathological evaluation in diagnosing such rare cases.