Inguinal Lymphadenopathy After Renal Transplantation Leading to the Diagnosis of Prostate Cancer: A Case Report

It is extremely rare for a patient with prostate cancer (PCa) to have palpable lymph nodes at the initial presentation. In fact, only 4 case reports of palpable superficial lymph nodes at the first visit led to the diagnosis of PCa. Moreover, no such cases are reported in kidney transplantation (KT) patients. A 72-year-old man who started hemodialysis due to diabetic nephropathy was referred to our hospital for a KT in 2018. Before the KT, he had a negative screen for cancer, including PCa. The postoperative course was good. He felt a lump in the left inguinal region three years after the KT. A computed tomography scan revealed abdominal and left inguinal lymphadenopathy, which was consistent with a post-transplant lymphoproliferative disorder. However, a biopsy of an inguinal lymph node revealed adenocarcinoma with positive prostate-specific antigen (PSA) staining, suggesting lymph node metastasis of PCa. The blood PSA level was 1674.23 ng/mL. A prostate biopsy was performed, the pathologic diagnosis of which was PCa, with a Gleason score of 10. In conclusion, even though the standardized incidence ratio of PCa is not known to increase in KT patients, PCa should be included in the differential diagnosis, along with the possibility of post-transplant lymphoproliferative disorder. We also suggest the importance of regular screening for malignant tumors after organ transplantation.