Post-CAR-T cell therapy presenting as proteinaceous lymphadenopathy

Diffuse large B-cell lymphoma (DLBCL) is the most common lymphoma and is often treated with chemotherapy, autologous stem cell transplant, and chimeric antigen receptor (CAR-T) cell therapy. Despite the increasing use of CAR-T therapy in various hematolymphoid malignancies, very little is known about pathologic effects on various tissues. We report a case of diffuse large B-cell lymphoma treated with CAR-T, with suspected relapse on PET scan. Pathology from an excisional biopsy showed no evidence of persistent diffuse large B-cell lymphoma, but instead showed extensive deposition of PAS positive, acellular material, consistent with proteinaceous lymphadenopathy. There is little known pathologic effects on malignant tissue following CAR-T therapy and we present one such undocumented finding of post-CAR-T cell therapy-induced proteinaceous lymphadenopathy.