RESUMO
Peripheral T-cell lymphomas are uncommon, accounting for only 10% to 15% of all non-Hodgkin lymphomas and their classification has been controversial. We report a case of peripheral T-cell lymphoma with angiocentric growth pattern which presented as a paratesticular tumoral nodule in a 47-year-old-man. Formalin-fixed paraffin-embedded samples from the paratesticular tumor and non-infiltrated adjacent tissue were submitted to histological, immunohistochemical, polymerase chain reaction (PCR)-based and in situ hybridization analysis. Histopathologically, there was a lymphomatous infiltrate in the paratesticular soft tissue, composed of a variable mixture of medium-sized to large cells with large cytoplasm and irregular-shaped nuclei, together with blood vessel destruction, necrosis and karyorrhexis. Immunohistochemical study revealed a high p53 expression in neoplastic cells that showed T cytotoxic immunophenotype, failing to express the natural killer (NK)-cell antigen CD56. A monoclonal rearrangement of the T-cell receptor (TCR) gamma gene by a PCR technique was demonstrated. Type-A Epstein-Barr Virus (EBV) DNA was detected by PCR-based analysis. A combined in situ hybridization and immunohistochemical study revealed that most cells labeled positive for EBV RNA showed immunostaining with the CD45RO antibody. Based on the above results, the case reported was classified as extranodal peripheral T-cell lymphoma with cytotoxic phenotype and EBV associated. The present case does not fit neatly into any of the specific types of peripheral T-cell lymphomas of the REAL classification, so a diagnosis of peripheral T-cell lymphoma unspecified was made.
