Introduction

Canine lymphoma is frequently found and has malignancy behavior. Both B and T neoplastic lineages are expanded and developed to lymphoma. Even this transformed malignancy is good response to multidrug chemotherapy, particularly CHOP or L-CHOP protocol; the recurrence remains occurred.

Objectives

To determine the minimal residual disease (MRD) in dogs before and after treatment with L-CHOP and evaluate the response.

Methods

Four dogs were diagnosed as multicentric B-cell lymphoma by cytology, histopathology and immunophenotyping employing with Pax5 and CD3 antibodies. Then, they were treated with modified L-CHOP protocol (L-asparaginase, vincristine, cyclophosphamide, doxorubicin and prednisolone). Whole blood was collected and evaluated for MRD by heteroduplex PCR detecting antigen receptor rearrangement (PARR) at week 0, 4 and 8, respectively.

Results

Histological assessment based on updated Kiel's classification showed that all four lymphomas were derived from B lymphocytes (Pax5+/CD3-). Three cases were high grade B-cell lymphoma; immunoblastic (n = 2), centroblastic polymorphic type (n = 1), while another was prolymphocytic, low grade B-cell lymphoma. Minimal residual disease of high grade B-cell lymphomas were absent in week 4 and 8 after treatments while that of low grade B-cell lymphoma remained presented. However, T-cell receptor γ genes were detected in week 8 from centroblastic polymorphic high grade B-cell lymphoma, observed a relapsing disease in week 10.

Conclusions

High grade B-cell lymphoma is sensitive to anti-cancer drugs than low grade B-cell lymphoma. Besides, two different clones of lymphoproliferative malignancies could develop in the dog. Thus, heteroduplex PARR could be used to monitor MRD in canine lymphoma and follow up for the recurrence.