Brobeil A, et al. - The role of terminal deoxynucleotidyl transferase (TdT) expression in the diagnosis of classical seminoma was determined. TdT expression in seminomas is a diagnostic pitfall in the differential diagnosis of lymphoblastic lymphoma/leukemia (LBL), especially since both possibly lack CD45 and/or CD20 expression. LBL was shownto be the most frequent secondary neoplasm in the patients in terms of relapse in long-term survivors of testicular cancer.