Cytotoxic Molecule-positive Epstein-Barr Virus-associated Peripheral T-cell Lymphoma in a 20-Month-old Child: A Case Report and Review of the Literature.

Peripheral T-cell lymphoma (PTCL) is rare in children. Expression of cytotoxic molecules (CM) in nodal PTCL has unique clinicopathologic features, including an Epstein-Barr virus (EBV) association. However, CM+, EBV-associated PTCL is extremely rare in the childhood, with only 1 study having been reported to date, including both pediatric and adult patients. We report a case of CM+ PTCL in a 20-month-old boy with left neck lymphadenopathy as well as multiple visceral lesions. A biopsied lymph node was diffusely infiltrated by atypical lymphoid cells with a CD4/CD8, granzyme B+, perforin+, and TIA-1+ phenotype, and EBV positivity by in situ hybridization. Rearrangements of the TCR γ-chain and β-chain genes were demonstrated by polymerase chain reaction. Ancillary genetic studies detected trisomy 2, trisomy 10, a structurally abnormal 6p, and additional copies of the IRF4 gene. Multiple bone marrow biopsies failed to show any evidence of tumor, histiocytic hyperplasia, or hemophagocytosis. This lesion was therefore diagnosed as "CM+, EBV-associated high-grade peripheral T-cell lymphoma." After 5 cycles of chemotherapy, the patient was in remission 8 months following initial diagnosis. To our knowledge, this represents the youngest child with this rare tumor in the published literature, and showing an unusually favorable initial response to therapy.