**Lungs fail to collapse properly on opening the chest and can weigh more than twice the normal weight
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**Impressions of the ribs remain on the visceral pleura
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**Lungs are a mottled grey/ tan colour - the lesions can vary from irregular grey speckling to homogeneous grey consolidation
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**Rubbery in consistence
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**Diaphragmatic lobes most affected
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**Associated bronchial and mediastinal lymph nodes are often enlarged
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*Histologically
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**Major features are extensive lymphoid proliferation around perivascular, peribronchial and peribronchiolar sheaths associated with pulmonary lymphatics
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**Many of these areas contain germinal centres and smooth muscle hyperplasia (in walls of terminal bronchioles and alveoli)