Sequential development of B-cell lymphoma of alternative lineage after treatment for mantle cell lymphoma in a dog

Abstract

An 11-year-old spayed female Chihuahua visited this hospital as a regular follow-up for the previous splenomegaly problem. Ultrasound examination revealed an enlarged spleen with a honeycomb appearance. Fine needle aspiration and polymerase chain reaction for antigen receptor rearrangement of lymphocytes suggested possible B-cell lymphoma, and the subsequent splenectomy and histopathology led to a diagnosis of mantle cell lymphoma. The patient was then monitored with no further treatments. On day 511, the peripheral lymph nodes were found enlarged, leading to a diagnosis of intermediate grade B-cell lymphoma. Genome sequencing analysis revealed that the splenic mantle cell lymphoma and lymph node lymphomas were dissimilar and that they arose independently of one another. Although our observations imply that splenic mantle cell lymphoma was treated successfully with splenectomy alone, a subsequent independent malignancy arose in the same patient.