Clinicopathological and immunophenotypical features of canine intravascular lymphoma (malignant angioendotheliomatosis).

Intravascular lymphoma (IVL) is a rare angiotropic large-cell lymphoma in which neoplastic lymphocytes proliferate within the lumina of blood vessels in the absence of a primary extravascular mass or leukaemia. A retrospective review of veterinary medical records identified 17 cases of canine IVL. Spinal cord ataxia (seven dogs), posterior paralysis (one dog), seizures (four dogs) and vestibular disease (three dogs) dominated the clinical presentation. Haemorrhage, ischaemia, and occasional foci of vascular proliferation were found in tissue sections from affected dogs. Vessels, predominantly veins, throughout the body were frequently filled with neoplastic lymphocytes. Splenic involvement occurred in only one of 10 cases examined and bone marrow involvement was absent in four cases examined. Formalin-fixed paraffin wax-embedded tissues from 15 cases were examined immunohistochemically with streptavidin-biotin-horseradish peroxidase and a catalysed signal amplification system. The neoplastic cells were classified in eight cases as T cells (CD3+/IgG-/CD79a-), in one case as B cells (CD3-/CD79a.dim/IgG+), and in the remaining six cases as non-T, non-B (CD3-/IgG-/CD79a-). The clinical and pathological features of canine IVL closely resembled those of the human disease. In striking contrast to human cases, which are most often B-cell lymphomas, the immunophenotypes of the canine IVLs in this series were heterogeneous. The canine IVLs were derived primarily from T cells and non-T, non-B lymphocytes, B cells being found in only a single instance.

Monoclonal immunoglobulin G cryoglobulinemia and multiple myeloma in a domestic shorthair cat.

A 13-year-old castrated domestic shorthair cat was examined because of fever, anorexia, and dermatologic lesions. Crusting, erythema, and well-demarcated purple discoloration of the foot pads and the tips of the pinnae, nose, and tail were seen. A white flocculent precipitate was detected in cooled serum. This precipitate dissolved upon rewarming, consistent with a cryoglobulin. Hypercalcemia, high alanine and aspartate aminotransferase activities, thrombocytopenia, and a monoclonal IgG gammopathy were found. Numerous hepatic nodules were detected by means of abdominal ultrasonography. Cytologic evaluation of fine-needle aspirates of the liver and spleen revealed numerous plasma cells, and evaluation of a bone marrow aspirate revealed plasmacytosis. A diagnosis of multiple myeloma and monoclonal IgG cryoglobulinemia was made, and the cat was euthanatized.