Lymphoproliferative Disorder in an Esophageal Cancer Patient Treated with Pembrolizumab.

A 75-year-old man diagnosed with esophageal cancer and lung metastasis received a combination of fluorouracil, cisplatin, and pembrolizumab. During pembrolizumab maintenance therapy, lymphoproliferative lesions at the lips and mouth and multiple lymph node swellings appeared. Histologically, Epstein-Barr virus (EBV)-encoded RNA was positive, and EBV-DNA was detected in the blood. The patient was diagnosed with other iatrogenic immunodeficiency-associated lymph proliferative disorders (OIIA-LPDs) related to EBV activation induced by pembrolizumab. Rituximab was administered, resulting in the improvement of the OIIA-LPD. The emergence of an OIIA-LPD merits close attention in patients receiving immune checkpoint inhibitors.