Left Lower Lobe Collapse

Introduction

The Left Lower Lobe collapse is sometimes missed because it can be hidden behind the heart shadow. This potential for diagnostic failure is increased if a lateral view is not included in the series.

Important Characteristics of all Lobar Collapse

1. Collapse and consolation can occur independently or together

2. Collapse can be partial or complete

3. It is often not clear to what extent the appearance is due to collapse or consolidation or both. The degrees of each are often unclear.

4. If a lobe is only partially collapsed and there is no accompanying consolidation, there may be no increase in opacity

5. In cases of pure collapse, only when the collapse is virtually complete will there be a significant increase in density of the affected lung

The Left Lower Lobe Anatomy

adapted from <a class="external" href="http://books.google.com.au/books?id=Bif0zpmEWtAC" rel="nofollow" target="_blank">By Fred W. Wright Radiology of the Chest and Related Conditions: Together with an Extensive Illustrative Collection of Radiographs CRC Press, 2002</a>	The left lower lobe is similar in structure to the right lower lobe except that it has two segments combined- because the anterior and medial basal segments share a common bronchial supply, these two segments are characteristically combined, forming an anterior medial basal segment. More information on lung anatomy here
adapted from <a class="external" href="http://books.google.com.au/books?id=Bif0zpmEWtAC" rel="nofollow" target="_blank">By Fred W. Wright Radiology of the Chest and Related Conditions: Together with an Extensive Illustrative Collection of Radiographs CRC Press, 2002</a>

Plain Film Appearance

The PA view will show a triangular area of increased opacity behind the left heart shadow. There may be loss of visualisation of the left hemi-diaphragm behind the heart There may be elevation of the left hemi-diaphragm
In the lateral view, a triangular opacity will be seen at the base of the lung There may be loss of the normal darkening of the thoracic vertebral bodies inferiorly

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