Cáceres Corner Case 232 – Vignette

Dear friends, today I am showing radiographs of a 43-year-old man with fever.


1. RUL pneumonia
2. RUL collapse
3. Mucous impaction
4. None of the above 

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Findings: There is a triangular pulmonary opacity in the upper lung that at first glance looks like RUL collapse, limited by the minor fissure (A, arrow). There are two important negative findings against collapse : the right hilum is not elevated and the trachea is not displaced to the right. Also the lateral view does not show any signs of RUL collapse. A careful look discovers a trigone in the upper part of the fissure (A, red arrow), raising the possibility of pneumonia within an azygos lobe.

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The patient was treated with antibiotics. A radiograph three weeks later shows complete resolution of the pneumonia and an azygos lobe (C, arrow).

Final diagnosis: Pneumonia in an azygos lobe simulating RUL collapse

I am showing this case to emphasize the importance of negative findings. In this patient they lead to a reevaluation of the image, leading to the discovery of the azygos fissure.

A correct diagnosis avoids unnecessary and potentially expensive additional procedures. Three years ago I was abroad and had an unenhanced abdominal CT which gave an equivocal diagnosis, leading to a three-days hospital stay and a hefty bill.

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