Site icon European Diploma of Radiology

Dr. Pepe’s Diploma Casebook 169 – SOLVED

Dr. Pepe

Dear Friends,

Presenting a new case of “Big little findings”. Preoperative chest radiograph for meniscus surgery in a 56-year-old woman.

What do you see?

Click here to see the answer

Findings: PA view shows a small right hemithorax. There is elevation of the right hemidiaphragm and a small hilum (A, red arrow). The findings are very suggestive of RLL lobectomy. The oblique fissure in the RLL represents the displaced minor fissure (A, white arrow). Previous CT shows a normal-size right lung with a ground-glass opacity in the RLL (B, arrow).

Final diagnosis: RLL lobectomy for adenocarcinoma of the lung

I am showing this case to discuss displacement of the lung fissures, an important finding that can indicate partial collapse of the underlying lobe. Usually, lobar collapse is detected because of the increased opacity of the lobe. Occasionally, the collapsed lobe retains much of its air, so a shift of the fissure may be the only sign of collapse.

A potential pitfall of fissure displacement is previous surgery, as seen in the case presented. In my experience, excluding previous surgery, aerated lobar collapse occurs mainly in the following conditions:

1. Inflammatory peripheral lung disease
2. Central lobar bronchial obstruction
3. Rounded atelectasis

NORMAL ANATOMY
The right minor fissure is visible in about 50% of chest radiographs as a straight horizontal line at the level of the right hilum (Fig. 1, A and B) The right and left major fissures are not visible in the PA film because their course is not tangential to the x-ray beam. (A, curved dotted lines). They are both visible as oblique lines in the lateral view (B).

Fig. 1
Fig. 2. PA radiograph showing the minor fissure (A, arrow). The lateral view shows both the right minor and major fissures (B, white arrows) and the upper portion of the left major fissure (B, red arrow)

Inflammatory lesions can cause scarring which diminishes the size of the affected lobe. TB is the most common cause in upper lobes. Bronchiectasis is the predominant cause in lower lobes. Both conditions can show an aerated lobe with loss of volume (Figs. 3-5).

Fig. 3. 68-year-old woman with previous history of TB. There is aerated partial collapse of RUL as evidenced by the elevated minor fissure (A and B, white arrows). Fibrotic changes are seen in the apex (A and B, red arrows). An incidental finding is calcification of breast prostheses.
Fig. 4. RLL collapse secondary to bronchiectasis. There is an oblique line at the right base (A, white arrow) that simulates an inferior accessory fissure. However, the right hilum is markedly low (A, red arrow), indicating loss of volume of RLL. Coronal CT shows marked RLL collapse with bronchiectasis, outlined by the displaced major fissure (B, arrow).
Fig. 5. 56-year-old man with previous TB. Lateral view shows forward displacement of the left major fissure (A, arrows), indicating partial collapse of LUL. PA radiograph depicts marked elevation of left hilum (B, arrow), secondary to fibrotic TB.

Central lobar bronchial obstruction is occasionally associated with aerated lobar collapse. It is thought to be due to collateral air ventilation through incomplete fissures (Figs. 6-7).

Fig. 6. Routine follow-up of an 82 y.o. man who underwent surgery for laryngeal carcinoma 10 years ago. PA view shows abnormal left hilum and blurring of the left cardiac contour (A, arrow). Lateral view shows marked forward displacement of the left major fissure (B, arrows) indicating severe LUL collapse.

Unenhanced axial CT confirms the marked LUL collapse (C, white arrow) secondary to endobronchial obstruction (C, red arrow). CT taken one year earlier shows an endobronchial lesion (D, red arrow) and discrete forward displacement of the major fissure (D,E, white arrows). These changes were overlooked. Surgical diagnosis: bronchogenic carcinoma

Fig. 8. Aerated RLL collapse in central carcinoma. PA radiographs shows a very low right major fissure (A, red arrow), better depicted in the cone down view (B, arrow). The left hilum is descended (A, white arrow). Bronchoscopy discovered a carcinoma of the RLL bronchus. The oblique line in the RUL corresponds to a scar.

Rounded atelectasis is a common cause of fissure displacement. It occurs secondary to spiral folding of the lung parenchyma when fixed by thickened pleura. The consequence is a peripheral rounded opacity in an aerated collapsed lobe. The volume loss, detected by the displaced fissure, avoids possible confusion with a true nodule in the plain film.

Fig. 9. Asymptomatic 49-year-old man with rounded atelectasis. Notice the visibility of the left major fissure, indicating LLL volume loss (A, arrows). Lateral view shows an ill-defined posterior opacity which corresponds to the rounded atelectasis (B, arrow).

Axial and sagittal CT confirm displacement of the left major fissure (C and D, white arrows), the small LLL, and the posterior rounded atelectasis (C, red arrow).

As a final thought, occasionally you may find fissure displacement without an apparent cause (Fig. 10).

Fig. 10. 92-year-old man, asymptomatic. PA radiograph shows downward displacement of the minor fissure (A, white arrow), major fissure (A, yellow arrow) and right hilum (A, red arrow). In a previous film four years earlier, the minor fissure (B, yellow arrow) and the right hilum (B, red arrow) were moderately descended. Since the patient was 92 y.o. and had no symptoms, his physician decided not to do a CT scan. My impression is that he has fibrotic changes in the RLL, which is not unusual in advanced age.


Follow Dr. Pepe’s advice:
1. A displaced fissure may be the only manifestation of aerated lobar collapse (always exclude previous surgery).

2. Most common causes:

a) Peripheral lobar inflammatory disease

b) Central bronchial obstruction

c) Rounded atelectasis

Exit mobile version