Development of Diffuse Large B-cell Lymphoma Serendipitously Led to Life-Saving Treatment in a Patient with Refractory Classical Hodgkin Lymphoma.

A 65-year-old man with generalized lymphadenopathy was diagnosed with classical Hodgkin lymphoma-mixed cellularity via left cervical lymph node biopsy. Initial treatment with doxorubicin, bleomycin, vinblastine, and dacarbazine led to complete metabolic remission (CMR); however, recurrence developed after 6 months. Brentuximab vedotin induced partial remission followed by systemic relapse after 10 months. Nivolumab led to a second CMR, but disease progression persisted over nearly 4 years, despite treatment adjustments and local radiotherapy. Eventually, the patient was diagnosed with diffuse large B-cell lymphoma during routine esophagogastroduodenoscopy. Four courses of rituximab-CHOP therapy led to a CMR. This case highlights the importance of performing re-biopsies to detect the recurrence or progression of lymphoma.