A Unique Case of Extramedullary Relapse in Acute Lymphoblastic Leukemia: Testicular to Ocular, Cardiac, and Colonic Involvement and the Role of Sperm Phenotyping in Diagnosis-Case Report and Literature Review.

Acute lymphoblastic leukemia (ALL) is a malignant condition of lymphoid progenitor cells that primarily affects the pediatric population, but also adults. The 5-year survival rate is 90% in children and approximately 40% in adults, with survival increasing through the use of peripheral stem cell allotransplantation (SCT). The relapse rate after stem cell transplantation (SCT) in adult acute lymphoblastic leukemia (ALL) patients ranges from 35% to 45%, making relapse a major cause of death in this population. We present an atypical case of late testicular involvement in ALL in a 50-year-old man diagnosed with ALL pro-T in remission post-chemotherapy (GMALL 2003 protocol) and allogeneic stem cell transplantation (alloSCT) from a related donor. This case describes a 50-year-old male with ALL pro-T who experienced three rare extramedullary relapses post-chemotherapy and alloSCT. Five years after remission, he had a unilateral testicular relapse confirmed by immunophenotyping of spermatic fluid. Despite no bone marrow involvement, he was treated with chemotherapy, intrathecal therapy, and bilateral testicular radiotherapy. He later relapsed in the orbit, controlled by radiotherapy, followed by a third relapse in the heart and colon. This case highlights the unusual sites and consecutive nature of extramedullary relapses in adult ALL.