Expression of terminal deoxynucleotidyl transferase (TdT) in classical seminoma: a potential diagnostic pitfall

• Published in: Virchows Archiv : an international journal of pathology Vol. 472; no. 3; pp. 433 - 440
• Main Authors: Brobeil, Alexander, Wagenlehner, Florian, Gattenlöhner, Stefan
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.03.2018; Springer Nature B.V
• Subjects: Acute myeloid leukemia; Adult; Biomarkers, Tumor - genetics; Biomarkers, Tumor - metabolism; Cancer; CD20 antigen; CD45 antigen; Deoxyribonucleic acid; Diagnosis, Differential; Diagnostic systems; Differential diagnosis; DNA; DNA nucleotidylexotransferase; DNA polymerase; DNA Repair - genetics; DNA-directed DNA polymerase; Gene expression; Humans; Immunohistochemistry; Immunohistochemistry - methods; Leukemia; Lymphocytes; Lymphocytes T; Lymphoma; Male; Medical diagnosis; Medicine; Medicine & Public Health; Middle Aged; Myeloid leukemia; Nuclei; Original Article; Pathology; Precursor Cell Lymphoblastic Leukemia-Lymphoma - diagnosis; Precursor Cell Lymphoblastic Leukemia-Lymphoma - genetics; Seminoma; Seminoma - diagnosis; Seminoma - genetics; Seminoma - metabolism; Testes; Testicular cancer; Testicular Neoplasms - diagnosis; Testicular Neoplasms - enzymology; Testicular Neoplasms - genetics; Thymus; Tumors; Seminona; Testis; Acute leukemia; TdT; Aberrant; Pitfall
• ISSN: 0945-6317; 1432-2307
• DOI: 10.1007/s00428-018-2313-5

Seminomas are the most frequent testicular tumors and in spite of specific markers some histological subtypes can be diagnostically challenging due to the potential overlap of morphologic features and a variant antigen expression. Terminal deoxynucleotidyl transferase (TdT) is a DNA polymerase present in hematogones, thymic T cells, lymphoblastic lymphoma/leukemia (LBL), and in some cases of acute myeloid leukemia but so far has not been described to be expressed in seminomas. After observing a reactivity of TdT in one case of seminoma, we analyzed ten additional tumors by immunohistochemistry to determine their spectrum of reactivity for TdT. In all seminoma cases investigated (10/10) as well as in two tumor-associated germ cell neoplasias in situ (2/2) the TdT staining intensity was variable but was often moderate to strong and restricted to the nucleus. We conclude that TdT expression in seminomas could represent a diagnostic pitfall in the differential diagnosis of LBL, particularly because both may lack CD45 and/or CD20 expression and—concerning relapse in long-term survivors of testicular cancer—LBL is the most frequent secondary neoplasm in the patients.