2020 Volume 73 Issue 1 Pages 47-51
A case of acute erythremic myelosis (pure erythroleukemia) was detected in a Japanese Black cow with depression and emaciation. The white blood cell count was not very high, but there was a high percentage of neoplastic cells on blood smears. Necropsy examination showed marked enlargement of the spleen and some lymph nodes. The spleen, lymph nodes and thymus were almost completely replaced by neoplastic cells. The cells sometimes expressed hemoglobin (Hb), but the other lymphohematopoietic markers tested were absent. In contrast to a previously reported case with several mature erythroid cells, the current case was composed mostly of large blastic cells and was diagnosed as a blastic type of acute erythremic myelosis, which has not been reported in cattle to our knowledge. The diagnosis of erythroid neoplasms is usually based on Giemsa-stained smears of blood or bone marrow in veterinary literature. However, this report suggests that the diagnosis is more correct when Hb immunohistochemistry is applied to smears or formalin-fixed, paraffin-embedded tissue.
