Equis ISSN 2398-2977

Lymphoproliferative disorders

Synonym(s): Lymphosarcoma, lymphoma, lymphoid neoplasia, lymphoid leukemia

Contributor(s): Katherine Edgar, Clare Knottenbelt, Prof Derek Knottenbelt, Anna Hollis


  • See bone marrow disorders: overview Bone marrow: disorders - overview and Lymphosarcoma: overview.
  • Rare.
  • No age, breed or sex predilection.
  • Has been reported from fetus to geriatrics.
  • Cause: acute or chronic proliferation of malignant lymphocytes.
  • Classification: lymphoma of B-cell, T-cell or mixed cell lineage with or without metastatic leukemic spread to the bone marrow/primary lymphoblastic or lymphocytic leukemia of B-cell, T-cell or mixed cell lineage.
  • Signs: non-specific clinical signs.
  • Diagnosis: clinical signs, hematology, lymph node and bone marrow biopsy Bone marrow: biopsy.
  • Treatment: supportive therapy, surgical excision of single masses, chemotherapy, radiotherapy.
  • Prognosis: poor for generalized disease, occasionally cutaneous lymphomas can be successfully treated, usually with radiotherapy or a combination or radiotherapy and surgery.
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  • Any immune cells that develop from a neoplastic cell may increase their production of inflammatory mediators and can become defective in their ability to phagocytize micro-organisms and increase or decrease immunoglobulins secretions.


  • Lymphoma is characterized by a sarcomatous proliferation of lymphoid tissue and disseminated by the lymph vessels, with late stage hematological spread to other organs including the bone marrow.
  • Lymphoid leukemia is characterized by the unregulated proliferation of bone marrow derived lymphoid cell lines crowds out or inhibits normal blood cell replication.
  • Solid tumors are not usually a feature of lymphoid leukemias.
  • Immunosuppression → secondary bacterial and fungal infections.
  • If immune-mediated hemolytic anemia is present, then icterus may be observed.
  • Hemorrhagic diathesis is caused by thrombocytopenia Thrombocytopenia: overview.


  • Some cases have a relatively insidious onset over months to years.
  • May present as acutely ill and survive for up to a couple of months without treatment.


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Further Reading


Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Smith K M, Clark C K, Dark M J et al (2013) T cell rich, B cell lymphoma in the small colon of a yearling horse. Equine Vet Educ 25 (2), 74-78 VetMedResource.
  • Rendle D I (2007) Clinical, immunophenotypic and functional charactierzation of T-cell leukemia in six horses. Equine Vet J 39 (6), 522-528 PubMed.
  • Henson F M D & Dobson J M (2004) Use of radiation therapy in the treatment of equine neoplasia. Equine Vet Educ 16 (6), 315-318 VetMedResource.
  • Lester G D, Alleman A R, Raskin R E et al (1993) Pancytopenia secondary to lymphoid leukemia in three horses. J Vet Intern Med 7, 360-363 PubMed.
  • Dascanio J J, Zhang C H, Anczack D F et al (1992) Differentiation of chronic lymphocytic leukemia in the horse - A report of two cases. J Vet Intern Med 6, 225-229 PubMed.
  • Furr M O, Crisman M V et al (1992) Immunodeficiency associated with lymphosarcoma in a horse. JAVMA 201 (2), 307-309 PubMed.
  • Grindem C B, Roberts M C et al (1988) Large granular lymphocyte tumor in a horse. Vet Path 26 (1), 86-88 PubMed.
  • Bernard W V, Sweeney C R & Morris F (1988) Primary lymphocytic leukemia in a horse. Equine Pract 10 (10), 24-30 VetMedResource.
  • Van den Hoven R & Franken P (1983) Clinical aspects of lymphosarcoma in the horse. Equine Vet J 15 (1), 49-53 PubMed.
  • Roberts M C (1977) A case of primary lymphoid leukemia in a horse. Equine Vet J (4), 216-218 PubMed.
  • Neufield J L (1973) Lymphosarcoma in the horse - A review. Can Vet J 14, 129-135 PubMed.

Other sources of information

  • Byrne B A, Yvorchuk-St. Jean K, Couto C G & Kohn C W (1991) Successful Management of Lymphoproliferative Disease in Two Pregnant Mares. In: Proceedings of the Annual Conference of the Veterinary Cancer Society. pp 8-9.