Immune-Mediated Hemolytic Anemia Associated with Cutaneous Lymphoma in a Dog
A nine-year-old male mixed-breed dog was examined because of peracute lethargy, exercise intolerance, and anorexia. The owner had noticed a solitary lip nodule six months ago. On physical examination, the dog had tachycardia, very pale mucous membranes, a lip nodule (2 cm in diameter) and splenomegaly. There were no palpable lymph nodes. Hematological evaluation revealed a severe immune-mediated hemolytic anemia (IMHA) with polychromasia, spherocytosis and autoagglutination. Except for mild hyperbilirubinemia, biochemical screening (urea, creatinine, alanine aminotransferase, calcium and alkaline phosphatase) was within normal limits. The blood smear examination was negative for parasites. Urinalysis showed bilirubinuria. Thoracic radiography showed cardiomegaly and left side hypertrophy. Abdominal radiography and ultrasonography confirmed diffuse splenomegaly. Cutaneous lymphoma was diagnosed after fine-needle aspiration biopsy of the lip nodule. The cytological exam identified a general high cellular density and fragility with a monotonous presentation and a low mitotic index. The cells were medium sized, with indistinct nucleoli and a scarce cytoplasm. Based on these findings the tumor was classified as a High Grade Cutaneous Malignant Lymphoma of Lymphoblastic type. Bone marrow examination was negative for neoplastic cells. The dog was treated with immunosuppressive doses of corticosteroids (prednisone 2 mg/kg/bid), one blood transfusion and intravenous fluids. Treatment resulted in marked clinical improvement and the packed cell volume rose from 4.2% to 28.6% within two weeks. Prednisone tapering was initiated at that time and the animal was without symptoms during the next four months. There was a marked reduction of the nodule size and the hemogram remained normal under therapy. Death of unknown cause occurred 5 months after the first consultation. Necropsy was not possible.
In dogs, IMHA is most often classified as idiopathic. Although very rare in dogs1, IMHA secondary to lymphoproliferative disorders is well described in human patients2, including in cutaneous lymphoma3. The authors report a rare case of a severe, steroid-responsive immune hemolytic anemia associated with cutaneous lymphoma.
1. MD Lucroy et al, 1998, Comparative Haematology International, 8:1-6
2. BC Gehrs, RC Friedberg, 2002, Am J Hematol, 69(4):258-71
3. F Misa, M Megido, 1993, Acta Haematol, 89(3):168