Respiratory 4 Flashcards
Neoplasia of the Respiratory System
Benign Primary Tumors (upper and lower respiratory tract):
Epithelial
Papilloma or Papillary adenoma — named by prominent growth pattern
Bronchiolar-alveolar adenoma (lung) — named by the likely site of origin
Neoplasia of the Respiratory System
Benign Primary Tumors (upper and lower respiratory tract):
Mesenchymal
Fibroma — Fibroblast
Osteoma — Osteocyte
Hemangioma — Endothelial cell
Malignant Primary Tumors of the Epithelial tissue:
Upper airway
Squamous cell carcinoma
Malignant Primary Tumors of the Epithelial tissue:
Upper airway and lung:
Adenocarcinoma: The most frequent neoplasm arising from respiratory or sinus epithelium. Adenosquamous carcinoma is a morphologic variant that shows squamous differentiation. Alveolar and Bronchiolar-alveolar carcinomas are named based on presumed site of origin
Ovine (retroviral) pulmonary adenocarcinoma and Enzootic carcinoma
There is a group of diseases presenting with chronic pneumonia and/or nasal and pulmonary neoplasia that are associated with…
Retroviral infections.
**Ruminant enzootic nasal carcinoma is also associated with retroviral infections.
Ovine retroviral pulmonary adenocarcinoma (also referred to as pulmonary adenomatosis and jaagsiekte)
Lesions:
Lungs are heavy, wet, do not collapse. Lobes develop firm grey nodules, that progress from the cranioventral lobes to a generalized distribution. The neoplastic epithelial cells have a papillary or acinar growth pattern and are classified as bronchoalveolar carcinoma.
The virus causing OPP (ovine progressive pleuropneumonia), also called Maedi, is an ovine lentivirus that causes interstitial pneumonia. This virus is similar to that causing ovine retroviral pulmonary adenocarcinoma, but neoplasia is not associated with OPP; The viruses can co-infect sheep.
Pulmonary Tumors
Primary lung tumors
Overall, primary lung tumors are considered rare in veterinary species and are typically of epithelial origin
The cell of origin is most often Clara cells or type Il pneumocytes from bronchioalveolar region
Primary pulmonary tumors often metastasize within the same and/or across multiple lung lobes.
Benign and malignant mesenchymal tumors of the respiratory tract:
Fibroma - Fibrosarcoma
Chondroma - Chondrosarcoma
Osteoma - Osteosarcoma (secondary/metastasis)
*The benign forms of these tumors are more commonly found in large animal species.
Hemangioma - Hemangiosarcoma (more often secondary/metastasis)
Other malignant neoplasia seen in the thorax (lungs, mediastinum, pleura, pericardium) ..
Lymphoma (lymphosarcoma) - secondary
Malignant melanoma - secondary
Mesothelioma — primary from thoracic “mesothelium”.
Paraneoplastic syndromes associated with pulmonary neoplasia:
hypercalcemia (ex. lymphoma)
endocrinopathies (ex. ACTH secreted by pulmonary carcinoma cells causing Cushing’s)
hypertrophic osteoarthropathy (HO)(periosteal bone proliferation induced by several disease conditions including pulmonary neoplasia)
Metastasis
Pulmonary capillaries are the first capillary bed for metastases from the vena cava or pulmonary arteries.
Common secondary (metastatic) neoplasms in the lungs include:
Mammary, thyroid, and uterine carcinomas, and osteosarcoma, vaccination-site sarcoma, lymphoma (lymphosarcoma), malignant melanoma, and hemangiosarcoma.
“Feline lung-digit syndrome”
Unusual pattern of metastasis from the lung to the digits in cats;
associated with bronchial and bronchioalveolar carcinoma.
Metastasis to the lungs will typically have an ‘embolic pattern’ — multifocal related to vascular supply.
Mesothelioma
Malignant neoplasm of mesothelial cells
mesothelial cells are flat cells that coat the surfaces of organs and body cavities; they produce a small amount of fluid that acts as a lubricant
Mesotheliomas tend to produce a great deal fluid, thus they present with thoracic, pericardial, or peritoneal effusions, depending on where they are growing
Spread within the thorax or abdomen is via exfoliation and implantation; rarely metastasize to locations outside of the body cavity of origin .
Toxic diseases of the respiratory system
Inhaled gases:
The mucociliary blanket helps to neutralize most gases before they reach alveoli. At high enough concentrations water soluble gases will dissolve and irritate upper airway mucosa (chlorine, ammonia, sulfur dioxide, hydrogen chloride). Less soluble gases (nitrogen dioxide, phosgene, ozone) may
reach the lower airways before dissolving and damage bronchiolar epithelium or alveoli. Pulmonary edema is the most common pathologic change.
