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Pulmonary Neoplasia (view source)

Revision as of 21:10, 6 August 2008

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==Classification==
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*Although metastatic pulmonary tumours are common in the lung, primary pulmonary tumours are relatively rare in domestic animals (cf. humans)
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*However, primary tumours are more common in dogs and cats than in other animals
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*Classification of pulmonary tumours can be difficult due to the [[General Pathology - Disorders of Cell Growth#Metaplasia|metaplasia]] which can occur in both inflammation and in neoplasia
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**Bronchial papilloma
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**Bronchial adenoma/ carcinoma (arising from major airways)
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**Bronchioloalveolar adenoma/ carcinoma (arising from small airways or alveolar parenchyma - either secretory bronchiolar cells or type II epithelial cells)
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**Carcinoid: in humans, these tumours arise from neuroendocrine cells - rare in animals
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==Primary tumours==
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[[Image:Pulmonary carcinoma.jpg|right|thumb|100px|<small><center>Pulmonary carcinoma and emphysema (Image sourced from Bristol Biomed Image Archive with permission)</center></small>]]
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[[Image:Adenomatosis of lung.jpg|right|thumb|100px|<small><center>Adenomatosis (Image sourced from Bristol Biomed Image Archive with permission)</center></small>]]
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[[Image:Alveolar cell carcinoma.jpg|right|thumb|100px|<small><center>Alveolar cell carcinoma (Image sourced from Bristol Biomed Image Archive with permission)</center></small>]]
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*Most arise from pulmonary epithelium
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*Usually middle aged to old dogs and cats
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===Bronchogenic carcinoma===
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* In dogs usually invasive bronchogenic carcinomas mostly arising from hilar region an metastasise via the airways to other parts of the lungs
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*Types:
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**Squamous cell - large cells with vesicular nuclei
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**Adenocarcinoma - invasive and destructive, least malignant
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**Adenosquamous carcinoma - both squamous and glandular part in one tumour, common, similar to metastatic
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**Undifferentiated - very rare in animals
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*Large, irregular, pale, not well defined border
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*Spread through pulmonary lymphatics
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===Bronchioloalveolar tumours===
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*Most common in dogs
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*Arise from either secretory bronchiolar or alveolar type II epithelial cells, often both types in same tumour
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*May be an incidental necropsy finding
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*Often occur as solitary nodules at the periphery of the lung, occasionally multiple
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*Histologically:
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**Regular alveolar pattern
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*May resemble chronic inflammation or rapid metastatic spread of tumour from a primary elsewhere in the body
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===Sheep pulmonary adenomatosis (SPA/ Jaagsiekte)===
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*Also called '''pulmonary carcinomatosis'''
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*Infectious [[Bronchi and Bronchioles Inflammatory - Pathology#Infectious causes of bronchitis or bronchiolitis|bronchiolar]]-[[Lungs - inflammatory#Infectious causes of pneumonia|alveolar]] carcinoma caused by a [[Retroviridae|retrovirus]]
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*Commonest under intensive management systems which favour aerosol transmission  and close contact of disease
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*Behaves like chronic pneumonia
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*Takes months to years to express itself clinically as coughing and exercise intolerance
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*Gross pathology:
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**Heavy lungs which fail to collapse
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**The lesions progress from small firm grey/white nodular lesions to extensive confluent areas with replacement by neoplastic tissue
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**Cut surface oozes fluid
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**There is often coexistent infection present
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**Occasional metastases to bronchial and mediastinal lymph nodes can occur
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*Histopathology:
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**Widespread proliferation of alveolar (Type 2) and terminal bronchiolar epithelium, lining the alveoli and lower airways
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**Multiple neoplastic foci of cuboidal/columnar cells forming papillary projections into the lumen
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**Metastases of the same in the bronchial and mediastinal lymph nodes
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*There is no serological test, and diagnosis depends upon raising the animal by the hind limbs whereupon a clear fluid issues from the nose = "Wheelbarrow test"
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===Carcinoids===
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*Occasionally occur in animals, mainly in humans
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*Originate from neuroendocrine components of major airways
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*Microscopically:
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**Large number of small secretory granules
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===Granular cell tumours===
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*Also called '''myoblastomas'''
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*Mesenchymal origin
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*Occurs in [[Hindgut Fermenters - Horse - Anatomy & Physiology|horses]]
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*Grossly:
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**Multiple discrete of partially confluent nodules
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**Tend to be associated with major bronchi
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**May cause obstruction
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*Histologically:
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**Large polyhedral cells aggregation
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**Fibrovascular stroma
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===Lymphomatoid granulomatosis===
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*Occurs in dogs
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*Histologically:
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**Mixed, atypical lymphoreticular cells infiltrating one or more lung lobes
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**Tend to invade blood vessel walls and airways
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**Fibrous stroma
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**Many mitotic figures
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==Metastatic tumours==
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[[Image:Lung carcinoma.jpg|right|thumb|100px|<small><center>Lung carcinoma in a dog (Image sourced from Bristol Biomed Image Archive with permission)</center></small>]]
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[[Image:Metastatic fibrosarcoma.jpg|right|thumb|100px|<small><center>Metastatic fibrosarcoma in canine lung (Image sourced from Bristol Biomed Image Archive with permission)</center></small>]]
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[[Image:Metastatic sweat gland carcinoma.jpg|right|thumb|100px|<small><center>Metastatic sweat gland carcinoma in feline lung (Image sourced from Bristol Biomed Image Archive with permission)</center></small>]]
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*All are malignant by definition
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*Relatively common in domestic species
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*Examples of common metastatic tumours include :
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**Mammary carcinoma (dog and cat)
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**Haemangiosarcomas
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**[[Bones - hyperplastic and neoplastic#Osteosarcoma (OSA)|Osteosarcomas]]
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**Uterine adenocarcinoma (cattle)
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**Malignant melanoma (horse)
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*Often manifest as multiple nodules scattered throughout the parenchyma - these lesions are often referred to as "cannon-ball" metastases, in all lung lobes
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*Histological examination usually shows the metastases to resemble the primary tumour however they may be either better or less well differentiated
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*Sometimes the metastasis can be sen only microscopically, grossly the lungs are discoloured and more firm than usual
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*Disseminate widely through lymphatics
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*'''In horses'''
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**cranial mediastinal lymphosarcoma
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**pulmonary granular cell tumour
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**malignant melanoma
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**haemangiosarcoma
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**metastatic adenocarcinoma
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**metastatic carcinoma
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<big>A space occupying lesion in the canine lung may produce periosteal thickening of the long bone - [[Bones - hyperplastic and neoplastic#Hypertrophic osteopathy|'''Hypertrophic Osteopathy''']]</big>
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