An analysis of acute and follow-up HRCT features in 23 cases of Cryptogenic Organizing Pneumonia (COP)

Abstract

Aims: To evaluate spectrum of HRCT features at presentation, incidence of fibrosis and pattern associated with fibrosis in COP. Methods: All patients with biopsy proven COP (1992–2004) with full complement of HRCT scans, and clinical data were recruited. HRCT scans were evaluated for major pattern of lung abnormalities at presentation: airspace, reticular, nodular, mass-like/focal, perilobular and mixed pattern (combination of any of above). Air-space was defined by confluent, patchy/random, bronchocentric, and segmental/lobar consolidation, and ground glass opacities. Reticular opacities, intralobular septal thickening, honeycomb, architectural distortion, volume loss and traction bronchiectasis defined fibrosis. Clinical data were retrieved from institutional database and case notes. Results: Of 23 patients [14M, 49.9 6 16.1 yrs], 2 were lost to follow-up, 5 died from other causes. Co-morbidities were haematological malignancies (n = 6), autoimmune disorders (7), and carcinoma (2). Duration of clinical follow-up was 50.7 6 44.9 (1–129) months in 21 patients. 17 patients underwent serial scans [35.9 6 31.6 (7–192) months]. 4 patients relapsed. Major patterns at presentation were airspace (9), reticular (0), nodular (2), mass-like (3), perilobular (2) and mixed (7). Reticular opacities were noted with other patterns in 8 patients. Fibrosis was evident in 8 patients; residual parenchymal bands/minimal reticulation in 6, and complete resolution in 3. Reticular opacities (p , 0.05) and mixed pattern at presentation (p , 0.05) was associated with fibrosis on follow-up. Co-morbidity, relapse and age had no association with fibrosis, which developed in 3/8 (37%) patients with airspace pattern, and none with mass-like pattern. Conclusion: COP presents with spectrum of lung abnormalities. Airspace and mixed patterns are commonest. Nodular, perilobular and mass-like presentations are uncommon. Presence of reticular opacities and mixed pattern are associated with development of fibrosis in COP.