The first autopsy case of Epstein–Barr virus‐positive marginal zone lymphoma that deteriorated after COVID‐19 vaccination

This is the first autopsy case of Epstein–Barr virus‐positive marginal zone lymphoma (EBV + MZL) with an other iatrogenic immunodeficiency‐associated lymphoproliferative disorders (LPD) (methotrexate [MTX]‐associated LPD) that deteriorated after the severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) vaccine. This case had a unique immunophenotype. A 71‐year‐old female patient with rheumatoid arthritis receiving MTX presented with fatigue 1 week after the SARS‐CoV‐2 vaccination. She was hospitalized due to hepatorenal dysfunction and pancytopenia. Computed tomography revealed systemic lymphadenopathy. Her physical condition deteriorated, and the patient died. The autopsy revealed systemic lymphadenopathy comprising medium‐sized atypical lymphocytes and scattered Hodgkin/Reed–Sternberg (H/RS)‐like cells. An immunohistochemical examination showed that atypical lymphocytes were positive for CD79a and MUM‐1 and some were positive for CD20 and IRTA‐1. H/RS‐like cells were immunoreactive for CD30 and CD15 and ringed by T cells. Both cell types were positive for EBV‐encoded small RNA. The majority of H/RS‐like cells were positive for CD20, whereas a small number of CD3‐positive cells were admixed. We herein presented the first autopsy case of EBV + MZL that deteriorated after the SARS‐CoV‐2 vaccination.