The Bulging Fissure Sign
The bulging fissure sign is usually seen in the right upper lobe in cases of lobar pneumonia, although not exclusively in this lobe. Thick exudative secretions lead to lobar expansion and result in bulging of the horizontal fissure.
Other causes to consider are any 'space-occupying' lesion such as cancer, abscess or haematoma.
This common exam case requires the candidate to think laterally about causes.
In an older patient or a known smoker then malignancy becomes more likely and must be mentioned as a priority with a suggestion of referral to the lung multidisciplinary team meeting (MDTM) and CT scanning
In a younger non smoker then infection is more likely. Staph aureus and Klebsiella followed by Strep pneumoniae and Pseudomonas are usually responsible for the bulging fissure. A suggestion of treatment with antibiotics and a repeat chest radiograph is a reasonable approach.
If quizzed, that radiograph should ideally be carried out 6-weeks after the completion of the antibiotics. Too soon and it won't have had a chance to clear.