The secondary pulmonary lobule: normal and abnormal CT appearances

Area of Science:

• Pulmonary Medicine
• Radiology
• Pathology

Background:

• The secondary pulmonary lobule is a fundamental unit of lung anatomy.
• High-resolution computed tomography (HRCT) allows detailed visualization of lobular structures.
• Interstitial lung diseases can manifest with characteristic alterations within the secondary pulmonary lobule.

Purpose of the Study:

• To compare the HRCT appearance of normal secondary pulmonary lobules with those affected by interstitial diseases impacting lymphatic channels.
• To identify specific HRCT features differentiating lymphangitic carcinomatosis, sarcoidosis, and lymphangioleiomyomatosis.

Main Methods:

• High-resolution CT (HRCT) imaging was employed.
• HRCT findings of secondary pulmonary lobules were analyzed in three patients with distinct interstitial lymphatic diseases.
• Comparison was made between normal lobular morphology and pathological changes.

Main Results:

• Lymphangitic carcinomatosis and sarcoidosis showed thickened interlobular septa and bronchiolovascular bundles.
• Sarcoidosis exhibited lobular distortion due to fibrosis, unlike lymphangitic carcinomatosis.
• Lymphangioleiomyomatosis presented with intralobular cysts, often obscuring normal lobular architecture.

Conclusions:

• HRCT effectively visualizes secondary pulmonary lobule abnormalities in lymphatic interstitial lung diseases.
• Distinct HRCT patterns aid in differentiating lymphangitic carcinomatosis, sarcoidosis, and lymphangioleiomyomatosis.
• Morphological changes within the secondary lobule are key indicators of specific interstitial pathologies.