Felis ISSN 2398-2950

Mediastinal lymphoma

Synonym(s): Thymic lymphoma, thoracic lymphoma

Contributor(s): Laura Garrett, Philip K Nicholls, Isabelle Desmas-Bazelle


  • Lymphoma in the mediastinum of cats affects the lymph nodes in the cranial mediastinum and/or the thymus.
  • Mediastinal/thymic lymphoma comprises 10-20% of feline lymphomas.
  • Male and young Siamese appear to be overrepresented.
  • Cause: historically most (>80-85%) cases were associated with feline leukemia virus which can cause malignant transformation of lymphocytes but this is no longer the case following widespread FeLV vaccination.
  • Signs: associated with respiratory system (dyspnea, coughing, tachypnea) and/or esophagus (anorexia, regurgitation, dysphagia, drooling).
  • Diagnosis: radiography, ultrasonography, computed tomography, cytology, histopathology, flow cytometry, PCR for antigen rearrangement.
  • Treatment: thoracocentesis, chemotherapy, radiation therapy.
  • Prognosis: overall median survival time approximately 12 months (32 months for cats achieving a complete response to chemotherapy).



  • Historically most (>80-85%) cases were associated with feline leukemia virus Feline leukemia virus disease, which can cause malignant transformation of lymphocytes. This is no longer the case following widespread FeLV vaccination.


  • FIV+ cats are at increased risk for development of lymphoma Lymphoma.


  • Clinical signs arise from:
    • (1) Compression/invasion of local mediastinal structures.
    • (2) Pleural effusion Pleural effusion, contributing to respiratory distress (along with direct effects of mass).
  • Hypercalcemia Hypercalcemia: overview is rare in thymic/mediastinal lymphoma.
  • The FeLV associated lymphomas are usually T-cell lineage; non-retroviral-associated. FeLV is a retrovirus of the family Oncovirinae. Viral integration into the host genome activates host proto-oncogenes such as c-myc or within flit-1 locus (this domain may influence lymphoagenesis). Disease spectrum appears to be determined by key sequences in long terminal repeats and surface glycoprotein (SU) envelope genes of the virus.


  • Incidence may be falling due to use of FeLV vaccines.


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Further Reading


Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Rick T, Kleiter M, Schwendenwein I, Ludewig E, Reifinger M et al (2019) Contrast-enhanced ultrasonography characteristics of intrathoracic mass lesions in 36 dogs and 24 cats. Vet Radiol Ultrasound 60, 56-64 PubMed.  
  • Fabrizio F, Calam A E, Dobson J M et al (2014) Feline mediastinal lymphoma: a retrospective study of signalment, retroviral status, response to chemotherapy and prognostic indicators. J Feline Med Surg 16(8), 637-644 PubMed.  
  • Patterson M M, Marolf A J (2014) Sonographic characteristics of thymoma compared with mediastinal lymphoma. J Am Anim Hosp Assoc 50(6), 409-413 PubMed.  
  • Fujino Y, Liao C-P, ZhaoY S,  Pan J, Mathes LE (2009) Identification of a novel common proviral integration site, flit-1, in feline leukemia virus induced thymic lymphoma. Virology 386, 16-22 PubMed.  
  • Sato H, Fujino Y, Chino J, Takahashi M, Fukushima K et al (2014) Prognostic Analyses on Anatomical and Morphological Classification of Feline Lymphoma. J Vet Med Sci 76(6), 807-811 PubMed.  
  • Louwerens M, London C A, Pedersen N C, Lyons L A (2005) Feline Lymphoma in the Post–Feline Leukemia Virus Era J Vet Intern Med 19, 329-335 PubMed.  
  • Chandhasin C, Coan P N & Levy L S (2005) Subtle mutational changes in the SU protein of a natural feline leukemia virus subgroup A isolate alter disease spectrum. J Virol 79 (3), 1351-1360 PubMed.
  • Henninger W (2003) Use of computed tomography in the diseased feline thorax. J Small Anim Pract 44 (2), 56-64 PubMed.  
  • Teske E, van Straten G, van Noort R et al (2002) Chemotherapy with cyclophosphamide, vincristine, and prednisolone (COP) in cats with malignant lymphoma: new results with an old protocol. J Vet Intern Med 16 (2), 179-186 PubMed.
  • Kristal O, Lana S E, Ogilvie G K et al (2001) Single agent chemotherapy with doxorubicin for feline lymphoma: a retrospective study of 19 cases (1994-1997). J Vet Intern Med 15 (2), 125-130 PubMed.
  • Malik R, Gabor L J, Foster S F et al (2001) Therapy for Australian cats with lymphosarcoma. Aust Vet J 79 (12), 808-817 PubMed.
  • Gabor L J, Malik R, Canfield P J (1998) Clinical and anatomical features of lymphosarcoma in 118 cats. Aust Vet J 76 (11), 725-732 PubMed.
  • Vail D M, Moore A S, Ogilvie G K et al (1998) Feline lymphoma (145 cases): proliferation indices, cluster of differentiation 3 immunoreactivity, and their association with prognosis in 90 cats. J Vet Intern Med 12 (5), 349-354 PubMed.
  • Day M J (1997) Review of thymic pathology in 30 cats and 36 dogs. J Small Anim Pract 38 (9), 393-403 PubMed.
  • Davies C & Forrester D S (1996) Pleural effusion in cats: 82 cases (1987 to 1995). J Small Anim Pract 37 (5), 217-224 PubMed.
  • Anilkumar T V, Voigt R P, Quigley P J et al (1994) Squamous cell carcinoma of the feline thymus with widespread apoptosis. Res Vet Sci 56 (2), 208-215 PubMed.

Other sources of information

  • Withrow & MacEwen's Small Animal Clinical Oncology (2020) 6th Edition.  Saunders.
  • Ettinger S J & Feldman E C (2005) Textbook of Veterinary Internal Medicine. 6th Edition. Elsevier Saunders.
  • Iyer D, LeRoy B E, Latimer K S & Moore H (2005) Feline Leukemia Virus Infection A Review. Available at URL: http://www.vet.uga.edu/vpp/clerk/iyer/ Accessed 6th November 2005.
  • Rogers K S (2001) Ch 68 Evaluation and treatment of cranial mediastinal masses. In: August, J. R. (ed) Consultations in Feline Internal Medicine 4, pp 533-540. WB Saunders Co.
  • Tilley P & Smith F W K The 5 Minute Veterinary Consult, 3rd Edition. Lippincott, Williams and Wilkins.