*'''[[Alveolar fluid]]'''. {{further|Alveolar fluid|linebreak=no}}
*'''Vascular congestion''', which can usually be seen easiest in the alveolar walls. It indicates left sided heart failure, especially when seen together with [[alveolar fluid]].
*'''Inflammatory''' cells, where a mild to moderate lymphocytic infiltrate is consistent with with heart failure, while neutrophils indicate pneumonia. '''[[pigmented macrophagesof the lung]]''' of the lung may indicate chronic heart failure.
*'''Mycobacteria''' in regions of the world with substantial prevalence
*'''Carcinoma''' {{further|Lung tumor|linebreak=no}}