Pleural signs of small peripheral pulmonary masses: pathologic correlation with chest radiographs and diagnostic...

The current interest in 'cost-effectiveness' of medical imagings means that chest radiography is the primary radiological examination of lung diseases. We attempted to investigate the pathological basis of different pleural signs, and determine their usefulness in differentiating small bronchogenic carcinomas from tuberculomas by using chest radiographs.

We prospectively studied 30 small solitary pulmonary masses, including 24 carcinomas and 6 tuberculomas. All 30 resected lobe specimens were investigated with preoperative radiographs, postoperative specimen radiographs, 10-15 microns thick whole-mount sections, and 5 microns thick slices for conventional histological examination. To evaluate the clinical usefulness of these pleural signs, we also retrospectively reviewed 100 chest radiographs and conventional tomographs of 1-3 cm peripheral pulmonary lesions, including 60 bronchogenic carcinomas and 40 tuberculomas.

The results confirmed that, besides the previously known interlobular septal fibrosis with pleural retraction, the pathologic basis also included the pleural puckering and adhesion with fluid collection for the 'tail' and 'rabbit ears' signs, and pleural dimpling with fluid collection and peripheral fibrous hyperplasia for the 'triangular shadow' signs. In the retrospective group, the pleural signs with adjacent pleural thickening was significantly more frequent in tuberculomas than in carcinomas (P < 0.05, chi 2-test).

Pleural signs associated with adjacent pleural thickening seems to contribute to differentiating granulomas from carcinomas. The pathological basis for this radiological finding includes visceral pleural fibrosis with the inflammatory cell infiltration, and the wide and shallow pleural dimpling filled with reactive pleural fluid.