Felis ISSN 2398-2950

Thorax: masses

Contributor(s): William Brewer Jr, Prof Richard Malik, Philip K Nicholls

Introduction

  • Masses can potentially be located in any part of the thorax (esophagus, heart base, lung, trachea, chest wall, rib, mediastinum and thymus).
  • Masses may be tumors, cysts, abscesses, granulomas, hematomas.
  • Rarely, diaphragmatic hernia with protrusion of liver and other abdominal organs into the chest can appear to be caudal mediastinal massess or even pulmonary masses.
  • Signs: respiratory distress, chest wall mass, cough, lethargy, regurgitation, hypertrophic osteopathy, myasthenia gravis, exfoliative dermatitis.
  • Diagnosis: physical examination, laboratory investigation, radiography, ultrasonography, cross sectional imaging (CT, MRI), scintigraphy.
  • Treatment: disease dependent.
  • Prognosis: disease dependent.

Pathogenesis

Etiology

  • Masses can potentially be located in any part of thorax:
    • Esophagus.
    • Heart base.
    • Lung.
    • Trachea.
    • Chest wall soft tissue.
    • Rib.
    • Mediastinum.
    • Thymus.
    • Ectopic thyroid tissue.
    • Cysts from residual tissue from embryological structures, eg cystic brachial arch.
    • Diaphragm (hernia).
    • Tracheobronchial lymph nodes.

Predisposing factors

General

  • Age, overall health status.

Pathophysiology

  • Space occupying lesion (extrapulmonary, intrapulmonary, mediastinal or pleural mass, but also hemothorax Hemothorax, chylothorax Chylothorax, pyothorax Pyothorax, pneumothorax Pneumothorax) in the thorax causes restrictive respiratory failure, typically with inspiratory dyspnea, rapid shallow breathing and hypoxia.
  • Esophageal mass: difficulty swallowing, regurgitation, weight loss, aspiration pneumonia  Pneumonia
  • Heart base mass Pericardium: neoplasia - heartbase tumor: pericardial effusion, muffled heart sounds, decreased amplitude ECG, secondary ascites or pleural effusion Pleural effusion.
  • Lung: dependent on size and/or location could be silent, cough, respiratory distress, dull breath sounds on side of mass, pleural effusion uncommon except for metastatic neoplasia, eg mammary carcinoma Mammary gland: neoplasia in the cat.
  • Trachea: cough, respiratory distress, increased upper airway sounds.
  • Chest wall soft tissue mass: variable sized external and/or internal chest wall mass, muffled breath and/or heart sounds, depending on location and size possible pleural effusion, spreading and/or invasion of ribs.
  • Rib mass: variably sized mass centered on rib, lytic and/or productive rib changes on thoracic radiographs, possible pleural effusion, muffled lung and/or heart sounds.
  • Mediastinum: silent, respiratory distress, difficulty swallowing, pleural effusion, elevated cranial thoracic trachea on thoracic radiographs, tissue or fluid dense anterior mediastinum on ultrasound.
  • Any thoracic mass: secondary hypertrophic osteopathy Hypertrophic osteopathy, a periosteal reaction of distal limbs thought to be secondary to increased blood flow mediated by vagus nerve.
    Also see HO with some renal or urinary bladder masses.
  • Thymoma Thymoma  may be associated with myasthenia gravis Myasthenia gravis and exfoliative dermatitis Feline cutaneous paraneoplastic syndromes.
  • Intrathoracic thyroid tumors Thyroid gland: neoplasia may cause hyperthyroidism.
  • Horners syndrome Horner's syndrome if lesion (usually cranial mediastinal) interferes with thoracic sympathetic pathways.
  • Some mediastinal masses Mediastinal disease can cause the "cranial vena caval syndrome" with edema of the head and neck, sclera congestion and jugular distention.

Timecourse

  • Variable, acute   →   chronic.
  • Acute onset of signs more typical of certain etiologies, eg mediastinal hemorrhage, lymphoma Mediastinal lymphoma.

Diagnosis

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Treatment

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Prevention

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Outcomes

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Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Tseng L W, Waddell L S (2000) Approach to the patient in respiratory distress. Clin Tech Small Anim Pract 15 (2), 53-62 PubMed.
  • Hawkins E C, DeNicola D B, Kuehn N F (1990) Bronchoalveolar lavage in the evaluation of  pulmonary disease in the dog and cat: state of the art. JVIM (5), 267-274 PubMed.

Other sources of information

  • Ettinger S J, Kantrowitz B (2005) Diseases of the trachea. In: Ettinger S J & Feldman E C, editorsTextbook of Veterinary Internal Medicine, St Louis, Elsevier.
  • Mertens M M, Fossum T W, MacDonald K A (2005) Pleural and extrapleural diseases. In: Ettinger S J &  Feldman E C, editors Textbook of Veterinary Internal Medicine, St Louis, Elsevier.
  • Moore L E, Biller D S (2005) Mediastinal disease. In: Ettinger S J &  Feldman EC, editors Textbook of Veterinary Internal Medicine, St Louis, Elsevier.
  • Nelson O L, Sellon R K (2005) Pulmonary parenchymal disease. In: Ettinger S J &  Feldman E C, editors Textbook of Veterinary Internal Medicine, St Louis, Elsevier.
  • Silverstein D, Drobatz K J (2005) Clinical evaluation of the respiratory tract. In: Ettinger S J & Feldman E C, editors Textbook of Veterinary Internal Medicine, St Louis, Elsevier.


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