Case of the week- Chest Medicine challenge - Answer for Case 1

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A 72-year-old man is admitted for increased shortness of breath, a cough productive of yellow sputum with scant hemoptysis, left pleuritic chest pain, and low-grade fevers. His past medical history is notable for hypertension and diabetes. He has a history of 80 pack-years of tobacco use, and was a ship-yard worker while in the military. On physical examination, his temperature is 38°C and his lung examination reveals decreased breath sounds on the left. His frontal and lateral chest radiographs are shown in Figure 158-A and Figure 158-B. What do you expect to observe on the chest CT scan?

A. Left pleural effusion.
B. Left upper lobe (LUL) consolidation.
C. LUL collapse.
D. Pleural thickening.

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This patient has developed complete LUL collapse as noted on the CT scan in Figure 158-C (choice C is correct).

Careful review of the plain frontal chest radiograph illustrates the main features of complete LUL collapse. The LUL is bigger than the right upper lobe due to the usual lack of a minor fissure on the left. When the LUL collapses, it tends to collapse anteriorly and somewhat superiorly and medially. On the frontal chest radiograph, there is a left hazy opacity/density in the upper left lung field (see Fig 158-A), which is readily apparent when the upper hemithoraces are compared. Due to volume loss, there is elevation of the left hemidiaphragm, upward retraction of the left hilum, and sometimes tracheal deviation to the left. The left pulmonary artery occupies the AP window. Because the lingula is part of the LUL, it appears as a hazy opacity silhouetting the left heart border, resulting in obscuration of this border.

Sometimes, vessels from the lower lobe can be seen presenting as linear opacities running vertically on the radiograph. The hyperexpanded left lower lobe (LLL) occupies the hemithorax, and the superior segment occupies the apical region of the hemithorax appearing as aerated lung. Sometimes, but not well demonstrated in this patient, there is a portion of the superior segment of the left lower lobe between the mediastinum and the collapsed left upper lobe abutting the arch of the aorta. The luftsichel, or air crescent sign is the name given to the appearance of aerated lung in this area. Alternatively, there may be loss of a discrete left mediastinal border, and obliteration of the aortic contour.

The chest CT scan illustrates the complete LUL collapse, showing the collapse anteriorly and medially with anterior displacement of the left major fissure. An endobronchial cut off sign of the LUL bronchus consistent with obstruction is noted (Fig 158-C, arrow). Bronchoscopy revealed an extrinsic endobronchial lesion, and pathologic findings revealed small cell carcinoma in this patient. The findings of LUL collapse can sometime be confused with pleural thickening because of the density and the nonsegmental borders, but careful review of the other radiographic features suggest LUL collapse (choice D is incorrect). A left pleural effusion, even if loculated, would appear denser, and one would not see superimposed lung markings (choice A is incorrect). Consolidation would appear dense with air bronchograms (choice B is incorrect).

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Mintzer RA, Sakowicz BA, Blonder JA. Lobar collapse: usual and unusual forms. Chest. 1988;94(3):615-620.

Woodring JH, Reed JC. Radiographic manifestations of lobar atelectasis. J Thorac Imaging. 1996;11(2):109-144.