Chronic basophilic leukemia with thrombocytosis treated with high-dose melphalan pulses in a canine patient

Myeloproliferative disorders are neoplastic diseases characterized by excessive proliferation and maturation of hematopoietic cells. These disorders may involve multiple hematopoietic lineages or a single lineage. Treatment typically consists of supportive care and antineoplastic agents, most commonly antimetabolites. Chronic basophilic leukemia is a rare myeloproliferative disorder involving the basophilic lineage, and is frequently associated with basophilia and thrombocytosis in canine patients. Therefore, differentiation from essential thrombocythemia is critical. Essential thrombocythemia is also a myeloproliferative disorder characterized by clonal platelet overproduction independent of growth factors. Only a limited number of cases of chronic basophilic leukemia with thrombocytosis have been reported in dogs. Additional case reports and diagnostic investigations are required to better characterize this condition. This report describes a canine patient diagnosed with chronic basophilic leukemia and thrombocytosis that was successfully treated with high-dose melphalan pulse therapy.