Cryptogenic Organizing Pneumonia Presenting as a Solitary Mass: Clinical, Imaging, and Pathologic Features

Abstract

BACKGROUND Cryptogenic organizing pneumonia (COP), with a variety of radiologic findings, is a clinical pathological entity characterized by the presence of granulation tissue composed of fibroblasts/myofibroblasts and loose connective tissue in the alveoli and/or the distal bronchioles. Nevertheless, the presence of a solitary mass in COP is relatively rare. This study investigated the clinical, imaging, and pathologic features of COP with solitary mass form. MATERIAL AND METHODS This retrospective analysis included 12 patients (9 men and 3 women; age range 36-78 years; mean age 60±9 years) with surgery- or biopsy-proven COP with a solitary lung mass, diagnosed between June 2012 and December 2017 at the Department of Radiology in our hospital. RESULTS All patients experienced cough with expectoration and 8 patients had hemoptysis. All lesions were adjacent to the pleura. Mean size of the lesions was 4.2±0.9 cm (range, 3.2-6.1 cm). The upper left lobe was the site of the lesion in 4 patients. Six masses had heterogeneous density; among these, 4 had cavities and distal obstructive inflammation. The mass caused pleural indentation in 4 patients. Lymphadenopathy was seen in 7 patients. All specimens showed buds of granulation tissue within the lumen of the distal pulmonary airspaces, with significant increase in interstitial lymphocytes in 4 specimens. CONCLUSIONS Patients with COP with solitary mass form are more susceptible to hemoptysis and the mass is prone to necrosis. Vascular bundles, exudation around the mass, interstitial lymphocyte infiltration, and mediastinal lymph node enlargement are common features.

Figure 1

Imaging data of 62-year-old man (Patient 4) who experienced cough and sputum with fever for 1 month. PET/CT image (A) shows a cavitated mass in the upper right lung. The edge is well defined, with a burr. PET fusion image (B) shows the high intake of the mass. The SUVmax is 8.8.

Figure 2

Imaging data of a 67-year-old woman (Patient 1) who experienced cough and sputum with hemoptysis for 3 months. CT scan MPR sagittal plane (A) and CT arterial enhancement (B) show a cavitated mass in the middle of the right lung. The mass is adjacent to the pleura, and the pleural indentation sign is visible. The edge of the mass is not clear. Around the mass, ground-glass opacity and fibrous lesions are visible. Arterial VR images (C) shows multiple blood vessels close to the mass (vascular bundles). MPR (D, E) shows the connection between the mass and bronchi. Image (E) shows bronchus truncation by the mucous plug.

Figure 3

Imaging data of a 63-year-old man (Patient 3) who experienced cough with hemoptysis for more than 1 month, with increased symptoms over the last 5 days. CT scan (A) and enhanced CT, arterial phase (B), shows a cavitated mass in the right upper lobe. The edge of the mass is fuzzy; the halo sign and a fibrous line around the lesion can be seen. (C) After 5 months of glucocorticoid treatment, the lesion almost disappeared; while a few ground-glass opacities and fibrous lesions remained. Enhanced CT, arterial phase (D), shows enlarged mediastinal lymph nodes with diameter >1 cm, and CT scan (E) shows decreased in size of the enlarged lymph nodes after treatment.

Figure 4

(A) H&E stained specimen (×200) shows granulation tissue in the alveolar space (arrows). No obvious damage can be seen in the alveolar structure; alveolar type II epithelial hyperplasia is present. The alveolar interval is widened, and a small amount of plasma cells and tissue cells can be seen in the interstitium. Marked lymphocytic infiltration is present. (B) H&E stained specimen (×200) shows granulation tissue (*) can be seen in the distal bronchioles.