Subtle pleural metastasis without large effusion in lung cancer patients: preoperative detection on CT

Abstract

Objective: We wanted to describe the retrospective CT features of subtle pleural metastasis without large effusion that would suggest inoperable lung cancer.

Materials and methods: We enrolled 14 patients who had open thoracotomy attempted for lung cancer, but they were proven to be inoperable due to pleural metastasis. Our study also included 20 control patients who were proven as having no pleural metastasis. We retrospectively evaluated the nodularity and thickening of the pleura and the associated pleural effusion on the preoperative chest CT scans. We reviewed the histologic cancer types, the size, shape and location of the lung cancer and the associated mediastinal lymphadenopathy.

Results: Subtle pleural nodularity or focal thickening was noted in seven patients (50%) having pleural metastasis and also in three patients (15%) of control group who were without pleural metastasis. More than one of the pleural changes such as subtle pleural nodularity, focal thickening or effusion was identified in eight (57%) patients having pleural metastasis and also in three patients (15%) of the control group, and these findings were significantly less frequent in the control group patients than for the patients with pleural metastasis (p = 0.02). The histologic types of primary lung cancer in patients with pleural metastasis revealed as adenocarcinoma in 10 patients (71%) and squamous cell carcinoma in four patients (29%). The location, size and shape of the primary lung cancer and the associated mediastinal lymphadenopathy showed no significant correlation with pleural metastasis.

Conclusion: If any subtle pleural nodularity or thickening is found on preoperative chest CT scans of patients with lung cancer, the possibility of pleural metastasis should be considered.

Fig. 1

Preoperative chest CT scans in a 37-year-old man with adenocarcinoma. A. Lung cancer is centrally located in the right middle lobe with mild contour bulging of the abutting interlobar fissure (arrows). The right minor fissure shows mild nodular thickening on the thin-section CT scan (arrowheads). B. The more inferior portion of the right major fissure is also thickened with nodularity (arrowheads). Open thoracotomy revealed diffuse nodularity of the pleura, and pleural metastasis was proven on biopsy.

Fig. 2

Preoperative chest CT scans in a 74-year-old man with adenocarcinoma. A. There is a primary lung cancer with spiculated peripheral margin in the left upper lobe. B. On the mediastinal window scan, plaque-like focal pleural thickening is noted in the mediastinal pleura (arrows) apart from the primary lung mass. Pleural metastasis of lung cancer was pathologically confirmed on open thoracotomy with biopsy.

Fig. 3

Preoperative chest CT scans in a 67-year-old man with adenocarcinoma. A. On the lung window scan, there is a cavitary peripheral lung cancer in the right upper lobe. B. There is focal plaque-like pleural thickening in the right posterior costal pleura (arrows) apart from the primary lung mass. Multifocal pleural thickening was also noted in the remaining areas (not illustrated).

Fig. 4

Preoperative chest CT scans in a 68-year-old woman with squamous cell carcinoma. A. There are luminal obliteration of the left upper lobar bronchus due to a central lung cancer and obstructive atelectasis in the distal lung. B. Small amount of left pleural effusion (arrows) is noted without any evidence of pleural nodularity or thickening. Pleural metastasis of lung cancer was proven on cytologic examination performed through open thoracotomy.