Mediastinal lymphoma

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Sections available in full article Introduction, Presenting signs, Acute presentation, Age predisposition, Breed predisposition, Special risks (e.g. anesthetic), Pathogenesis, Etiology, Pathophysiology, Epidemiology (population dynamics), Diagnosis, Presenting problems, Clinical signs, Diagnostic investigation, Gross autopsy findings, Histopathology findings, Differential diagnosis, Treatment, Initial symptomatic treatment, Standard treatment, Monitoring, Prevention, Prophylaxis, Sequelae, Prognosis, Expected response to treatment, Reasons for treatment failure, Sources, Publications, Vetstream contributor(s),
Contributors Dr Laura Garrett DVM DACVIM (Oncology)
Dr Philip K Nicholls BVSc BSc PhD MRCVS FRCPath
Synonyms Thymic lymphoma, thoracic lymphoma

Introduction

  • Lymphoma in the thorax of cats affects the lymph nodes in the cranial mediastinum and/or the thymus.
  • Mediastinal/thymic lymphoma comprises 10-20% of feline lymphomas  Lymphoma  .
  • Cause : most (>80-85%) cases are associated with feline leukemia virus which can cause malignant transformation of lymphocytes.
  • Signs : associated with respiratory system (dyspnea, coughing, tachypnea) and/or esophagus (anorexia, regurgitation, dysphagia, drooling).
  • Diagnosis : radiography, ultrasonography, computed tomography, cytology, histopathology.
  • Treatment : thoracocentesis, chemotherapy, radiation therapy.
  • Prognosis : FeLV negative cats have a much better prognosis than FeLV positive cats.

Diagnosis

Clinical signs

  • Due to mass effect:
    •  Respiratory:
      • Cough, tachypnea, dyspnea.
    •  Esophageal:
      • Regurgitation, vomiting, drooling.
  • Occasionally mass is palpable if extends cranial to thoracic inlet.
  • Occasionally see jugular distension, or edema of face/neck/forelimbs.
  • Horners syndrome or laryngeal paralysis  Larynx disease   are rare complications arising from peripheral nerve entrapment by mediastinal masses.

Diagnosis

Differential diagnosis

  • Thymoma  Thymoma   (check also for paraneoplastic syndromes such as myasthenia gravis  Myasthenia gravis   (ventroflexion, regurgitation, dysphagia) and exfoliative dermatitis, sometimes seen with thymoma).
  • Ectopic thyroid tissue (adenoma or, less likely, carcinoma); benign cranial mediastinal cyst.
  • Branchial cyst.
  • Consider other tumors: heart base tumor, lipoma, squamous cell carcinoma of thymus (rare).
  • Consider other masses: abscess, lymph node hyperplasia, hematoma, granuloma, excessive fat.
  • For effusions consider feline infectious peritonitis  Feline infectious peritonitis  .
  • Rarely, esophageal perforation with secondary bacterial mediastinitis may resemble mass lesion radiographically.
  • Signs may be confused with other cardiac or respiratory diseases eg congestive heart failure  Congestive heart failure  , cardiomyopathy  Heart: dilated cardiomyopathy (DCM)  , pneumothorax  Pneumothorax  , diaphragmatic hernia  Diaphragm: hernia  , chylothorax  Chylothorax  , pyothorax  Pyothorax  , etc.

Sequelae

Prognosis

  • FeLV negative cats have a much better prognosis than cats that are FeLV positive. Cats that respond to treatment and attain a remission after the first several treatments have a much better prognosis than cats that do not respond to therapy.

Expected response to treatment

  • The reported response rate of mediastinal lymphoma to chemotherapy varies widely from ~40-92%.
  • Doxorubicin maintenance after COP induction reported to give median remission of 281 days, compared with 83 days using COP maintenance.
  • FeLV+ cats have a median survival of approximately 4 months with chemotherapy treatment. FeLV- cats have a median survival of around 1 year. Some (~10%) cats will have prolonged remissions with treatment (>2 years).

Reasons for treatment failure

  • Resistance to chemotherapy.

Sources

Publications

Refereed papers

  • Recent references fromPubMed.
  • 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 Virol79(3), 1351-1360PubMed.
  • Henninger W (2003)Use of computed tomography in the diseased feline thorax.J Small Anim Pract44(2), 56-64 PubMed.  
  • Teske E, van Straten G et al(2002)Chemotherapy with cyclophosphamide, vincristine, and prednisolone (COP) in cats with malignant lymphoma: new results with an old protocol.J Vet Intern Med16(2),  179-186PubMed.
  • Kristal O, Lana S Eet al(2001)Single agent chemotherapy with doxorubicin for feline lymphoma: a retrospective study of 19 cases (1994-1997). J Vet Intern Med15(2), 125-130PubMed.
  • Malik R, Gabor L J et al(2001)Therapy for Australian cats with lymphosarcoma.Aust Vet J79(12), 808-817PubMed.
  • Gabor L J, Malik R et al(1998)Clinical and anatomical features of lymphosarcoma in 118 cats.Aust Vet J76(11),  725-732PubMed.
  • Vail D M, Moore A S 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 Med12(5), 349-354PubMed.
  • Day M J (1997)Review of thymic pathology in 30 cats and 36 dogs.  J Small Anim Pract38(9), 393-403PubMed.
  • Davies C & Forrester D S (1996)Pleural effusion in cats: 82 cases (1987 to 1995).J Small Anim Pract37(5), 217-224PubMed.
  • Anilkumar T V, Voigt R P, Quigley P J, Krausz T, Sarref C E & Alison M R (1994)Squamous cell carcinoma of the feline thymus with widespread apoptosis.Res Vet Sci56(2), 208-215PubMed.

Other sources of information

  • 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, pp533-540. WB Saunders Co.
  • Tilley P & Smith F W KThe 5 Minute Veterinary Consult,3rd Edition. Lippincott, Williams and Wilkins.
  • Withrow & MacEwenSmall Animal Clinical Oncology, 3rd Edition.  Saunders.

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