Partial 6 - Interstitial Lung Disease Flashcards
The interstitial space is defined as continuum of loose connective tissue throughout the lung composed of three subdivisions:
(1) The bronchovascular (axial), surrounding the bronchi, arteries and veins from the lung root to the level of the respiratory bronchiole
(2) The parenchymal (acinar), situated between the alveolar and capillary basement membranes
(3) The subpleural, situated beneath the pleura, as well as in the interlobular septae.
Patterns of interstitial lung diseases
Linear
Reticular
Nodular
Reticulonodular
Linear pattern
A linear pattern is seen when there is thickening of the interlobular septa, producing Kerley lines, Kerley A and Kerley B lines. The interlobular septa contain pulmonary veins and lymphatics.
Causes of linear pattern
The most common cause of interlobular septal thickening, producing Kerley A and B lines, is pulmonary edema, as a result of pulmonary venous hypertension of the lymphatics
Other causes: Mitral stenosis Malignant lymphoma Idiopathic pulmonary fibrosis Lymphangitic pulmonary fibrosis Pneumoconiosis Sarcoidosis Congenital lymphangiectasia
Reticular pattern
A reticular pattern results from the summation or superimposition of irregular linear opacities. The term reticular is defined as meshed, or in the form of a network. Reticular opacities can be described as fine, medium, or coarse, as the width of the opacities increases.
Causes of reticular pattern
A classic reticular pattern is seen with pulmonary fibrosis, in which multiple curvilinear opacities form small cystic spaces along the pleural margins and lung bases (honeycomb lung).
Nodular pattern
A nodular pattern consists of multiple round opacities, generally ranging in diameter from 1 mm to 1 cm. Nodular opacities may be described as miliary (1 to 2 mm, the size of millet seeds), small medium, or large, as the diameter of the opacities increases
Causes of nodular pattern
SHRIMP: Sarcoidosis Histiocytosis (Langhans cell histiocytosis) Hypersensitivity pneumonitis Rheumatoid nodule Infection (mycobacterial, fungal, viral) Metastasis Microlithiasis Pneumoconiosis (silicosis, coal worker`s, berylliosis)
Reticulonodular pattern
A reticulonodular pattern results from a combination of reticular and nodular opacities. This pattern is often difficult to distinguish from a purely reticular or nodular pattern, and in such a case a differential diagnosis should be developed based on the predominant pattern. If there is no predominant pattern, causes of both nodular and reticular patterns should be considered
An acute appearance suggests
Pulmonary edema or pneumonia
Reticulonodular lower lung predominant distribution with decreased lung volumes suggests
PAAC: Pulmonary fibrosis (idiopathic) Asbestosis Aspiration (chronic) Collagen vascular disease (Rheumathoid arthritis, SLE, Scleroderma)
Reticulonodular which have middle or upper lung predominant distribution suggests
(Mycobacterium Settle Superiorly in Lung): Mycobacterial or fungal disease Silicosis Sarcoidosis Langerhans cell histiocytosis
Associated lymphadenopathy suggests
SNIS:
Sarcoidosis
Neoplasm (lymphangitic carcinomatosis, lymphoma, metastates)
Infection (viral, mycobacterial, or fungal)
Silicosis
Associated pleural thickening and/or calcification suggests
Asbestosis
Associated pleural effusion suggests
PLLC: Pulmonary edema Lymphangitis carcinomatosis Lymphoma Collagen vascular disease
