Roberta R. Miller

The CT features of benign and malignant pleural diseases have been described. However, the accuracy of these features in the differential diagnosis of diffuse pleural disease has not been assessed before. Without knowledge of clinical or pathologic data, we reviewed the CT findings in 74 consecutive patients with proved diffuse pleural disease (39 malignant and 35 benign). The patients included 53 men and 21 women 23-78 years old. Features that were helpful in distinguishing malignant from benign pleural disease were (1) circumferential pleural thickening, (2) nodular pleural thickening, (3) parietal pleural thickening greater than 1 cm, and (4) mediastinal pleural involvement. The specificities of these findings were 100%, 94%, 94%, and 88%, respectively. The sensitivities were 41%, 51%, 36%, and 56%, respectively. Twenty-eight of 39 malignant cases (sensitivity, 72%; specificity, 83%) were identified correctly by the presence of one or more of these criteria. Malignant mesothelioma (n = 11) could not be reliably differentiated from pleural metastases (n = 24). We conclude that CT is helpful in the differential diagnosis of diffuse pleural disease, particularly in differentiation of malignant from benign conditions.

Edge and internal characteristics of pulmonary nodules evaluated with high-resolution computed tomography (HRCT) were correlated with the pathologic specimens in 93 patients. Speculation correlated pathologically with irregular fibrosis, localized lymphatic spread of tumor, or an infiltrative tumor growth pattern and was observed in six of 11 benign nodules (55%) and 74 of 85 malignant nodules (87%). Pleural tags were observed in three benign nodules (27%) and 49 malignant lesions (58%); pathologically, these represented fibrotic bands usually associated with juxta-cicatricial pleural retraction. Bubblelike areas of low attenuation within the nodule were observed in 21 malignant lesions (25%) and only one benign nodule (9%). They were observed most commonly in bronchioloalveolar carcinomas (seven of 14) and were due either to patent small bronchi or small, cystic spaces within neoplastic glands. Malignant nodules as a group were larger than benign lesions (P = .02) and more commonly demonstrated a spiculated contour (P less than .05), lobulation (P less than .001), and inhomogeneous attenuation (P less than .05).

Computed tomography (CT) was performed within 10 days of open lung biopsy in nine patients with fibrosing alveolitis. One-centimeter collimation contiguous scans through the chest were obtained in all patients. Additional 1.5-mm collimation scans were obtained in the area in which lung biopsy was later performed in six patients. In seven patients, CT demonstrated patchy involvement of the lung parenchyma, areas with a reticular pattern being intermingled with areas of normal lung. The reticular pattern was associated with cystic spaces 2-4 mm in diameter and was more severe in the lung periphery. Histologically, the reticular pattern corresponded to areas of irregular fibrosis. One patient had diffuse honeycombing (2-20-mm cysts), and one had honeycombing only in the lung periphery. In all patients, CT clearly defined the architectural changes seen on open lung biopsy. These changes were much better seen on the 1.5-mm than on the 10-mm collimation scans. CT may be helpful in determining the pattern and distribution of lung involvement in patients with fibrosing alveolitis and in guiding the surgeon to the most appropriate area(s) for biopsy.

Bronchiolitis obliterans organizing pneumonia is a disease characterized by the presence of granulation tissue within small airways and the presence of areas of organizing pneumonia. We retrospectively reviewed the chest radiographs, CT scans, and biopsy specimens in 14 consecutive patients with proved bronchiolitis obliterans organizing pneumonia. Six patients were immunocompromised because of leukemia or bone-marrow transplantation. In all patients, 10-mm collimation CT scans were available. In 11 of the 14 patients, select 1.5-mm scans were obtained. The CT findings included patchy unilateral (n = 1) or bilateral air-space consolidation (n = 9), small nodular opacities (n = 7), irregular linear opacities (n = 2), bronchial wall thickening and dilatation (n = 6), and small pleural effusions (n = 4). All patients had areas of air-space consolidation, small nodules, or both. A predominantly subpleural distribution of the air-space consolidation was apparent on the radiographs of two patients and on CT scans of six. Pathologically, the nodules and the consolidation represented different degrees of inflammation in bronchioles, alveolar ducts, and alveoli. Although most of the findings were apparent on the radiographs, the CT scans depicted the anatomic distribution and extent of bronchiolitis obliterans organizing pneumonia more accurately than did the plain chest radiographs.