2.16 VA Report Pearls – ILD Word Salad

Here are the definitions of some of the terms that came up today at our fabulous AM Report!!

DPLD – Diffuse Parenchymal Lung Disease – A more broad term than ILD, which is actually preferred nowadays, because many of the conditions which we are trying to describe in the category of ILD actually involve anatomic structures other than the interstitium, (technically the space between the epithelial and capillary endothelium basement membranes within the alveolus). This term represents a group of diseases which are characterized by inflammation and/or fibrosis of the bilateral lung parenchyma.

ILD – Interstitial Lung Disease – This is an older, typically used word for DPLD.

Ground Glass Opacities –  A term used in radiology to describe hazy areas of increased attenuation (radiodensity) which can represent filling of the alveolus (from water, pus, or blood) or alveolar collapse, or interstitial space thickening.

Reticulation – A term used in radiology to describe a net-like pattern of linear markings on an image.

Honeycombing – A term used in radiology to describe the appearance of cystic airspaces divided by thickened walls representing fibrous tissue. Dilated and thickened respiratory bronchioles in the lung periphery contribute to this appearance. This finding is associated with UIP.

Traction Bronchiectasis – Whereas bronchiectasis describes abnormally dilated bronchi, traction bronchiectasis refers specifically to bronchiectasis which occurs when fibrotic parenchymal changes cause the airways to be pulled open (hence traction) by scar as opposed to bronchiectasis that happens because of bronchial obstruction, for example.

Pulmonary Fibrosis – this is a nonspecific term sometimes used to describe bilateral parenchymal changes that are fibrotic in nature

IIP – Idiopathic Interstitial Pneumonia – Also known as noninfectious pneumonia. This is a group of seven subtypes of lung diseases that affect the interstitium and, sometimes, the airways. The seven subtypes are distinguished based on histology, and are desquamative interstitial pneumonia, diffuse alveolar damage, nonspecific interstitial pneumonia, respiratory bronchiolitis, usual interstitial pneumonia, organizing pneumonia, lymphoid interstitial pneumonia.

IPF – Idiopathic Pulmonary Fibrosis – This is a chronic disease characterized by scarring of lung tissue including the interstitium (see above), the airspaces, airways, and vessels. The cause is unknown (hence idiopathic) but the histological correlate is usual interstitial pneumonia, the most common of the idiopathic interstitial pneumonias.

UIP – Usual Interstitial Pneumonia – A histopathologic finding characterized by patchy interstitial fibrosis and thickening without active inflammation (not that many inflammatory cells). It can be caused by another condition, such as RA, or may not have a known cause, as in IPF.

 

NSIP – Nonspecific Interstitial Pneumonia – According Dr. Aliya Husain in Robbins – “The concept of nonspecific interstitial pneumonia emerged when it was realized that there is a group of patients with diffuse interstitial lung disease of unknown etiology whose lung biopsies fail to show diagnostic features of any of the other well-characterized interstitial diseases.”  It can be divided into two categories: cellular and fibrosing. The cellular pattern has chronic interstitial inflammation with lymphocytes and plasma cells. The fibrosing pattern looks like “interstitial fibrosis without the temporal heterogeneity that is characteristic of UIP.” These patients have a better prognosis than those with UIP which is why the difference matters.

Ref:

Robbins and Cotran – The pathologic basis of disease – 8th ed.

Paul Simonelli, MD http://www.columbia.edu/itc/hs/medical/pathophys/pulmonary/2006/pulm013106-SimonelliNotes.pdf

David Lederer, MD http://www.columbia.edu/itc/hs/medical/pathophys/pulmonary/2009/ILD_2009Color.pdf

Jannette Collins, MD and Eric J. Stern, MD (1998). “Ground glass opacity on CT scanning of the chest: What does it mean?” (PDF). Applied Radiology.

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