Histopathology of Canine Bone Marrow in Malignant Lymphoproliferative Disorders

Abstract. Bone marrow core~biopsies from 63 dogs with malignant lymphoproliferative disorders and leu-kemic involvement were evaluated. Multicentric lymphoma (44), multiple myeloma (8), chronic lymphocytic leukemia (9), and acute lymphoblastic leukemia (2) were found. Four distinct bone marrow histologic patterns were identified: focal (6), mixed (20), interstitial (28), and packed (9). Of those with focal or mixed patterns, 77 % (20126) had paratrabecular distribution. Stromal changes were infrequent, with 6 % (4163) having necrosis, 3 % (2163) fibrosis, and 6 % (4163) osteolysis. For each condition, the interstitial and mixed patterns were the most common presentations, while focal and packed patterns occurred less frequently. Morphologically, cells of metastatic lesions of lymphoma resembled those of primary sites. Colonization of bone marrow by various cytologic types of lymphoma was independent of the histologic patterns. The histologic appearance of canine malignant or non-neoplastic bone marrow conditions has been re-ported to a limited extent.l0,'1,15,'9.21 Determination of leukemic involvement in bone is important for the clinical staging of canine lymphoma, as it has been shown to affect treatment and progn~s is.~J ~ Vet-sified according to an adaptation of the types reported in human m e d i ~ i n e. ~ , ~ Material for this study was from dogs presented to th