Methotrexate-Associated Primary Cutaneous Epstein-Barr Virus-Positive Polymorphic B-Cell Lymphoproliferative Disorder With Metachronous T-Cell Clonally Related Angioimmunoblastic T-Cell Lymphoma: A Case Report and Review of the Literature.

Primary cutaneous Epstein-Barr virus (EBV)-positive polymorphic B-cell lymphoproliferative disorder (LPD) is a rare LPD associated with iatrogenic and endogenous immune dysregulation with the commonest risk factor being immunosuppressive therapy. We present a 55-year-old woman with rheumatoid arthritis, previously on methotrexate, who developed a waxing and waning papulonodular eruption on the chest and neck. Histopathology revealed a lymphohistiocytic infiltrate with atypical EBV + /CD30 + B cells, consistent with EBV + polymorphic B-cell LPD. Although discontinuation of methotrexate initially resulted in complete lesional resolution, recurrence occurred 2 years later while the patient was on rituximab therapy. The patient subsequently developed lymphadenopathy, and biopsy confirmed angioimmunoblastic T-cell lymphoma. Notably, earlier skin samples harbored the same T-cell clone found in the lymph node. This case underscores the dynamic evolution of EBV + polymorphic B-cell LPD, where an initial clonal T-cell response to infected atypical B cells eventuated into angioimmunoblastic T-cell lymphoma.