Incidental Detection of Bilateral Node-Positive Papillary Thyroid Carcinoma During Initial Staging for Localized Testicular Seminoma: A Case Report

The coexistence of testicular seminoma and papillary thyroid carcinoma (PTC) is uncommon.We report a 32-year-old man with localized pure testicular seminoma treated by right orchiectomy.Staging computed tomography, performed before adjuvant carboplatin, incidentally demonstrated bilateral thyroid lesions.Subsequent evaluation revealed a highly suspicious right thyroid nodule and suspicious cervical lymph nodes.Surgery demonstrated bilateral multifocal PTC with lymphatic invasion and cervical lymph node metastases.Radioiodine therapy was subsequently administered.Comprehensive germline testing using a 90-gene cancer-predisposition panel identified no pathogenic or likely pathogenic variants.The detection of thyroid abnormalities before systemic seminoma treatment makes a treatment-related origin of the PTC highly unlikely.This case highlights the importance of evaluating clinically relevant incidental findings during oncological staging and illustrates the unresolved relationship between testicular germ-cell tumors (TGCTs) and thyroid malignancies.