Superior accessory fissure

Case contributed by Dr Vikas Shah


Productive cough and shortness of breath and fever.

Patient Data

Age: 55 years
Gender: Male

Chest x-ray

Airspace opacification is present in the right mid-zone, sharply demarcated inferiorly by a horizontal line. This was assumed to be in the anterior basal segment of the right upper lobe, with the demarcating line being the horizontal fissure.

Due to concerns about lung malignancy (smoking history and some weight loss on further questioning), a CT was requested.


Airspace opacification is seen within the right lower lobe, demarcated inferiorly by an accessory fissure. There is mild centrilobular emphysema. The middle and upper lobes are clear, and the rest of the study was essentially normal.

Annotated image

The superior accessory fissure has a horizontal lie and in this case, lies just inferior to the plane of the horizontal fissure. It divides the right lower lobe into superior and basal segments.

Case Discussion

This case illustrates the anatomy of the fissures of the right lung. The fissures can aid in localizing pathology to certain lobes. Usually, when right mid zone opacification is demarcated inferiorly, it is due to pathology in the upper lobe being limited by the horizontal fissure. In this case, a similar x-ray appearance has been caused by opacification in the lower lobe being limited by an accessory fissure called the superior accessory fissure.

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Case information

rID: 51928
Published: 14th Mar 2017
Last edited: 14th Aug 2019
System: Chest
Inclusion in quiz mode: Included

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