Characterization of post transplantation lymphoma in feline renal transplant recipients

The development of malignant neoplasia following solid organ transplantation and immunosuppression is well recognized in man. Post-transplantation malignant tumours include non-melanoma skin cancers, non-Hodgkin's lymphoma and Kaposi's sarcoma and many of these cancers have a known or suspected viral cause. A similar increased incidence of cancer is seen in cats that have received a renal transplant and lymphoma is the predominant neoplasm in this population. This study examines a population of cats that received renal transplants at the University of Pennsylvania School of Veterinary Medicine and subsequently developed neoplasia. From 1998 to 2010, 111 cats were transplanted and 25 cats developed cancer (22.5%). Fourteen of the 25 cats were diagnosed with lymphoma (56%), making it the most common tumour in this patient population. The median interval between transplantation and diagnosis of lymphoma was 617 days and the median survival time (MST) following the diagnosis of lymphoma was 2 days. Tissues from seven of these cats were available for histopathological review as either samples collected at necropsy examination (n = 5) or biopsy submissions (n = 2). Five of these cats had multiorgan involvement with sites including the liver, spleen, peripheral and mesenteric lymph nodes, small intestine, urinary bladder, heart, mesenteric fat and body wall. Four of the cats with multiorgan disease had involvement of the renal allograft two of which also had lymphoma of the native kidney. All lymphomas were classified as mid to high grade, diffuse large B-cell lymphoma, which is also the most common lymphoma subtype in human cases of post-transplantation lymphoproliferative disorders.