Haruyuki Ishii1, Bruce C Trapnell2, Ryushi Tazawa3, Yoshikazu Inoue4, Masanori Akira5, Yoshihito Kogure6, Keisuke Tomii7, Toshinori Takada8, Masayuki Hojo9, Toshio Ichiwata10, Hajime Goto1, Koh Nakata11. 1. Department of Respiratory Medicine, Kyorin University Hospital, Tokyo, Japan. 2. Divisions of Pulmonary Biology and Medicine, Children's Hospital Research Foundation, Cincinnati, OH. 3. Bioscience Medical Research Center, Niigata University Medical and Dental Hospital, Niigata, Japan. 4. Department of Diffuse Lung Diseases and Respiratory Failure, Clinical Research Center, NHO Kinki-Chuo Chest Medical Center, Osaka, Japan. 5. Department of Radiology, National Kinki Chuo Hospital for Chest Disease, Osaka, Japan. 6. Department of Internal Medicine, NHO Nagoya Medical Center, Aichi, Japan. 7. Department of Internal Medicine, Kobe City Medical Center General Hospital, Hyogo, Japan. 8. Department of Respiratory Medicine, Niigata University Medical and Dental Hospital, Niigata, Japan. 9. Department of Respiratory Medicine, International Medical Center of Japan, Tokyo, Japan. 10. Department of Respiratory Medicine, Dokkyo University Hospital, Saitama, Japan. 11. Bioscience Medical Research Center, Niigata University Medical and Dental Hospital, Niigata, Japan. Electronic address: radical@med.niigata-u.ac.jp.
Abstract
BACKGROUND: Acquired pulmonary alveolar proteinosis (PAP) has been reclassified into autoimmune or secondary PAP according to the occurrence of serum granulocyte macrophage colony-stimulating factor autoantibody. Most patients undergo high-resolution CT (HRCT) scanning in order for physicians to make a differential diagnosis of diffuse lung diseases, but no information is available to distinguish the HRCT scan features of secondary PAP from those of autoimmune PAP. The objective of this study was to characterize the HRCT scan features of autoimmune and secondary PAP. METHODS: HRCT scans of 42 patients (21 patients each in the autoimmune PAP and secondary PAP groups) were centrally collected and evaluated in a blinded manner. RESULTS: Ground-glass opacities (GGO) were a major finding in both the autoimmune PAP and secondary PAP groups. In the secondary PAP group, GGOs typically showed a diffuse pattern (62%), whereas GGOs showed a patchy geographic pattern in the autoimmune PAP group (71%; p < 0.005). The so-called "crazy-paving" appearance and subpleural sparing were frequently seen in the autoimmune PAP group (both 71%), whereas they were less frequently seen in the secondary PAP group (14% and 33%, respectively). The involved area of GGO was even in craniocaudal distribution for the secondary PAP group, whereas it was predominant in the lower lung field compared with the upper lung field in the autoimmune PAP group (p < 0.05). CONCLUSIONS: Typical HRCT scan findings for autoimmune PAP patients were GGO with a patchy geographic pattern, subpleural sparing, crazy-paving appearance, and predominance in the lower lung field. These findings were rather infrequent for secondary PAP patients.
BACKGROUND: Acquired pulmonary alveolar proteinosis (PAP) has been reclassified into autoimmune or secondary PAP according to the occurrence of serum granulocyte macrophage colony-stimulating factor autoantibody. Most patients undergo high-resolution CT (HRCT) scanning in order for physicians to make a differential diagnosis of diffuse lung diseases, but no information is available to distinguish the HRCT scan features of secondary PAP from those of autoimmune PAP. The objective of this study was to characterize the HRCT scan features of autoimmune and secondary PAP. METHODS: HRCT scans of 42 patients (21 patients each in the autoimmune PAP and secondary PAP groups) were centrally collected and evaluated in a blinded manner. RESULTS: Ground-glass opacities (GGO) were a major finding in both the autoimmune PAP and secondary PAP groups. In the secondary PAP group, GGOs typically showed a diffuse pattern (62%), whereas GGOs showed a patchy geographic pattern in the autoimmune PAP group (71%; p < 0.005). The so-called "crazy-paving" appearance and subpleural sparing were frequently seen in the autoimmune PAP group (both 71%), whereas they were less frequently seen in the secondary PAP group (14% and 33%, respectively). The involved area of GGO was even in craniocaudal distribution for the secondary PAP group, whereas it was predominant in the lower lung field compared with the upper lung field in the autoimmune PAP group (p < 0.05). CONCLUSIONS: Typical HRCT scan findings for autoimmune PAP patients were GGO with a patchy geographic pattern, subpleural sparing, crazy-paving appearance, and predominance in the lower lung field. These findings were rather infrequent for secondary PAP patients.