Testicular seminoma with a progressing pulmonary nodule and mediastinal lymphadenopathy without retroperitoneal metastasis

Introduction Testicular germ cell cancer has a relatively good prognosis even if visceral and/or lymph node metastases are present thanks to chemotherapy. Yet chemotherapy can lead to various adverse events. Therefore, it is crucial to distinguish whether a suspected metastatic disease is metastasis or not. Case presentation A 33‐year‐old male visited our hospital to receive subsequent therapy for suspected recurrent seminoma with a progressing pulmonary nodule and mediastinal lymphadenopathy after orchiectomy. The pathological diagnosis of needle aspiration and resected specimen of the several lesions was consistent with epithelioid cell granuloma without caseous necrosis. Based on these findings, the lung and mediastinal lymph node lesions were diagnosed as sarcoidosis. Conclusion In cases where the simultaneous occurrence of other benign or malignant diseases is suspected, pathological confirmation is necessary for appropriate decision‐making.