Dr. Pepe’s Diploma Casebook: CASE 141 – SOLVED

Findings: PA radiograph shows marked downward displacement of the right hilum (A, white arrow) and verticalization of the intermediate bronchus (A, red arrow). These findings are indicative of marked volume loss of RLL. The lateral view (B) is unremarkable.

Enhanced coronal CT confirms the descended right hilum (C, white arrow), as well as the vertical intermediate bronchus (C, red arrow). A different slice shows a small calcified triangular shadow (D, arrow), which represents a markedly collapsed RLL.

Final diagnosis: severe RLL collapse due to previous TB

In the previous webinar (Diploma case 139), I described the common signs that suggest lobar collapse. In this presentation I want to review atypical forms of lobar collapse and how to recognize them.
The main signs of lobar collapse are volume loss and increased opacity of the lobe. Atypical presentations lack these traits, and the lobe appears to have an increased volume (drowned lobe) or to have collapsed without increased opacity (aerated collapse). A third variant would be a lobe that has lost most of its volume (extreme collapse) and therefore is difficult to identify as such, as occurred in the initial case.

In extreme collapse, the affected lobe is severely decreased in size and may be overlooked, or confused with a different process (Fig. 1). The diagnosis is suggested by secondary findings, such as hilar displacement and/or increased lucency of the unaffected lobe(s) (Figs. 2 and 3).

Enhanced axial CT image depicts a horizontal sliver of tissue, corresponding to the markedly collapsed RUL, sharply outlined by the minor fissure (C and D, white arrows). Note the obstructed RUL bronchus (D, red arrow). Bronchogenic carcinoma.

Enhanced axial CT shows the markedly collapsed lobe (C, arrow). Coronal CT depicts a mass obstructing the LLL bronchus (D, arrow). Final diagnosis: carcinoma.

Coronal and sagittal CT confirm the extreme LUL collapse with bronchiectasis. The major fissure is well depicted in the coronal and sagittal reconstructions (C and D, arrows).

The finding known as drowned lobe is a variant of lobar collapse in which the lobe does not decrease in size but instead, enlarges. It occurs when a slow-growing proximal tumor permits accumulation of distal secretions and infection, causing an increase in size of the lobe (Fig. 4). Bulky tumor masses may contribute to this enlargement (Fig. 5).

Enhanced axial and coronal CT shows the enlarged RUL lobe (C and D, white arrows), secondary to central obstruction of the RUL bronchus (C and D, red arrows). Diagnosis: drowned RUL secondary to central carcinoma

Enhanced axial CT confirms the swollen LLL (C, white arrow). PET-CT shows that part of the bulk is due to a large tumor mass (D, white arrow), invading the pulmonary veins and left atrium (C and D, red arrows).

In aerated collapse the lobe loses volume, but does not increase in opacity, making the collapse less obvious. This happens because increased opacity is not related with volume loss, but rather with the amount of secretions within the lobe. If the partially collapsed lobe contains air, the lobe will appear to have normal lucency.
In aerated collapse, the diagnosis is suspected by displacement of the hilum, the fissure, or both (Figs. 6-8).

Follow Dr. Pepe’s advice:

1. Common manifestations of lobar collapse are loss of volume and increased opacity.

2. Uncommon manifestations of lobar collapse are extreme collapse, drowned lobe, and aerated collapse.

3. These uncommon manifestations are suspected based on secondary signs: hilar and/or fissure displacement and increased lucency of the unaffected lobe(s).