Canine Ocular Intravascular Lymphoma: Lassoing a Rare Tumor Chuck Schobert, DVM, MS COPLOW, University of Wisconsin School of Veterinary Medicine

Introduction Rare, fatal canine cancer Humans, too Previous canine ocular reports Five cases, first presented as ocular disease Terminology change?

Human Intravascular Lymphoma (IVL) vs Canine IVL In general: –Multiple tissues –Despite vessels engorged with tumor cells, they still do not circulate (ie, can’t diagnose with CBC or bone marrow aspirate) –Proliferation as clusters in vessels with attachment to endothelium –Veins more than arteries

Human IVL B cell lymphoma AKA, angiotrophic or malignant endotheliomotosis Only one ocular report Cutaneous most common Only one report of tumor of phagocytic origin

Canine IVL Wide variety of tissues, 6/23 ocular A variety of IHC markers were examined  B cell lineage rare  T cell lineage more common  Other IHC markers of non-lymphoid origin such as those for histiocytic or macrophage antigens rarely used

Methods Over 5,600 cases of canine ocular neoplasia surveyed in COPLOW Searched for intravascular round cell tumors H & E slides evaluated microscopically

Inclusion Criteria Clusters of cells in vessel lumen Dark-staining, irregular nuclei, scant cytoplasm Adherent as clusters or rafts of cells Attachment to vessel endothelium Excluded three IVL lymphoma cases that did not meet these criteria

Phone Follow-up Survival time Metastatic disease Original presentation Treatment? If necessary and permissable, rDVM and owners were contacted

Immunohistochemistry CD3/T cell CD79a/B cell CD18 & MHC-II/macrophage  Not exlusive for macrophage  Used routinely for cells of histiocytic or macrophage origin

Hemotoxylin and Eosin

Case #Age/Breed Gender CD18MHC-IICD3CD79a 07RD17772/Lab/MN RD9064/DobieX/MN RD019310/Chow-Lab/FS ++ Weak ++ 03RD12919/Foxhound/FS RD0213/Akita/FS++ ++

Immunohistochemistry CD3CD79a CD18MHC-II

Immunohistochemistry 5/5 CD18 and MHC-II positive 3/5 T cell+, B cell + 1/5 T cell+ (CD3 +, CD79a -) 1/5 T cell-, B cell- (CD3-, CD79a-)

Discussion Found in variety of tissues Rare tumor over-represented in the eye Staining characteristics=macrophage lineage IV Lymphoma from human studies shows distinct features of a true lymphoma lineage Propose new name in canines: Intravascular Histiocytic Tumor

Acknowledgements Dr Dick Dubielzig Dr Howard Steinberg Dr Christiane Kafarnik Kate Lieber Histopath Laboratory