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Bronchioloalveolar Carcinoma (BAC) Is Less Round, More Often Has Air Bronchograms, Compared with Atypical Adenomatous Hyperplasia

April 15, 2009
Written by: , Filed in: Chest Radiology
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A recent study was conducted to identify CT features that can help differentiate pure ground-glass opacities (GGOs) as bronchioloalveolar carcinoma (BAC) versus atypical adenomatous hyperplasia.

It has concluded that pure ground-glass opacity lesions are more likely to be bronchioloalveolar carcinoma if they contain internal air bronchograms, and are more likely to be atypical adenomatous hyperplasia if they are spherical in shape.

The Study

35 patients who had BAC and 17 who had atypical adenomatous hyperplasia. All lesions were confirmed histologically with video-assisted thoracic surgery. All of these lesions manifested as pure GGOs.

In 12 patients, >1 GGO was present. In these patients, the largest histologically confirmed lesion was analyzed.

Methods
All CTs had thin sections obtained of the GGOs (section thickness 1.25 mm or 1.0 mm). No IV contrast was administered. For each GGO, the maximum diameter on axial, sagittal, and coronal planes was measured and averaged.

Mean attenuation of the lesion was measured using ROI cursors.

The GGOs were evaluated for degree of sphericity, degree of margin irregularity, presence of vascular convergence surrounding the nodule, presence of pleural retraction, and presence of air bronchograms.

Review for Practicing Radiologists The University of California, San Francisco School of Medicine, Department of Radiology and Biomedical Imaging Review for Practicing Radiologists an intensive clinical radiologic review and self-assessment covering the following radiology subspecialties: Vascular-Interventional, Breast, Neuro, Gastrointestinal and Pulmonary Imaging. The program is designed for radiologists in clinical practice. Click here to read more or order: Review for Practicing Radiologists --

 

Body Imaging: Abdominal, Thoracic and Vascular University of California, San Francisco, Department of Radiology Course Director: Judy Yee, MD This program is designed for the radiologist in clinical practice, and is intended to provide an overview and update on clinically relevant topics in diagnostic imaging and interventional techniques. Click here to read more or order: Body Imaging

Results
Univariate analysis demonstrated that patient age, nodule maximum diameter, nodule mean attenuation, and presence of internal air bronchograms were associated with BAC (P =0.012, P =0.006, P =0.023, and P <0.001, respectively).

The more spherical a nodule was, the more likely it was atypical adenomatous hyperplasia (P <0.001).

Multivariate analysis demonstrated that presence of internal air bronchograms was associated with bronchioloalveolar carcinoma (BAC) (P =0.007), and the more spherical a nodule was, the more likely it was atypical adenomatous hyperplasia (P =0.042).

In this study, 76.5% of atypical adenomatous hyperplasia lesions were spherical and 14.3% of BAC lesions were spherical; 77.1% of bronchioloalveolar carcinoma lesions contained air bronchograms, and 11.8% of atypical adenomatous hyperplasia lesions contained air bronchograms.

Conclusions
Pure ground-glass opacity lesions are more likely to be bronchioloalveolar carcinoma if they contain internal air bronchograms,  and are more likely to be atypical adenomatous hyperplasia if they are spherical in shape.

Reviewer’s Comments
One of the limitations of this study, which the authors acknowledge, is that all the pure GGO lesions in this series were either atypical adenomatous hyperplasia or BAC. No other causes of GGO lesions were included, such as inflammatory lesions.

Author: Vineet R. Jain, MD

Reference:
Oda S, Awai K, et al. Ground-Glass Opacities on Thin-Section Helical CT: Differentiation Between Bronchioloalveolar Carcinoma and Atypical Adenomatous Hyperplasia. AJR; 2008; 190 (May): 1363-1368

Review for Practicing Radiologists The University of California, San Francisco School of Medicine, Department of Radiology and Biomedical Imaging Review for Practicing Radiologists an intensive clinical radiologic review and self-assessment covering the following radiology subspecialties: Vascular-Interventional, Breast, Neuro, Gastrointestinal and Pulmonary Imaging. The program is designed for radiologists in clinical practice. Click here to read more or order: Review for Practicing Radiologists --

 

Body Imaging: Abdominal, Thoracic and Vascular University of California, San Francisco, Department of Radiology Course Director: Judy Yee, MD This program is designed for the radiologist in clinical practice, and is intended to provide an overview and update on clinically relevant topics in diagnostic imaging and interventional techniques. Click here to read more or order: Body Imaging
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