Individualized chemotherapy strategy in early-stage canine diffuse large B-cell lymphoma: a case report

Diagnosing early-stage canine diffuse large B-cell lymphoma (DLBCL) is challenging due to partial lymph node effacement, often requiring a multimodal approach. This report describes a stage II DLBCL case in an 11-year-old dog where definitive diagnosis was achieved by integrating histopathology, immunohistochemistry, and polymerase chain reaction for antigen receptor rearrangement after inconclusive initial testing. Treatment began with a CHOP (cyclophosphamide, hydroxydaunorubicin, oncovin, prednisone) protocol based on ex vivo chemosensitivity results but was de-escalated to vincristine monotherapy due to severe adverse events, including grade 4 neutropenia. Despite discontinuing chemotherapy due to persistent hematologic toxicity, the patient remains in complete remission 5 months post-treatment. This case illustrates the necessity of diagnostic validation in early-stage disease and suggests that chemosensitivity-guided therapeutic de-escalation can achieve effective control while minimizing toxicity.