Chronic lymphocytic leukemia transformation into high‐grade lymphoma: a description of Richter's syndrome in eight dogs

• Published in: Veterinary & comparative oncology 2017-06, Vol.15 (2), p.366-373
• Main Authors: Comazzi, S., Martini, V., Riondato, F., Poggi, A., Stefanello, D., Marconato, L., Albonico, F., Gelain, M. E.
• Format: Article
• Language: English
• Subjects: Animals; Cell Transformation, Neoplastic - pathology; chronic lymphocytic leukaemia; dog; Dog Diseases - pathology; Dogs; Female; flow cytometry; Flow Cytometry - veterinary; high‐grade lymphoma; Leukemia, Lymphocytic, Chronic, B-Cell - pathology; Leukemia, Lymphocytic, Chronic, B-Cell - veterinary; Lymphocyte Count - veterinary; Lymphoma, Non-Hodgkin - pathology; Lymphoma, Non-Hodgkin - veterinary; Male; Retrospective Studies; Richter syndrome; transformation
• ISSN: 1476-5810; 1476-5829
• DOI: 10.1111/vco.12172

Richter's syndrome (RS) is the development of an aggressive lymphoma in patients with chronic lymphocytic leukaemia (CLL). In humans, RS occurs in 2–20% of CLL, which transform into diffuse large B‐cell lymphoma but reports in dogs are scarce. This study retrospectively describes eight dogs with CLL progressing into RS. A database including 153 dogs with CLL (93T CD8+ and 55 B‐CLL) was interrogated and RS was demonstrated in eight cases (representing 5.2% of total CLL): two with T‐cell (2.2% of T CLL) and six with a B‐cell immunophenotype (10.9% of B‐CLL). When RS occurred, lymphocytes were decreased compared to CLL. Five dogs had anaemia and two dogs thrombocytopenia. Frequent clinical signs included lymph node swelling, coughing, vomiting, neurological signs and weight loss. Independently from the therapy, RS was associated with a short survival (median 41 days). RS should be considered as an unfavourable evolution in canine CLL.