9/16- Pathology of Interstitial Lung Diseases Flashcards Preview

Symptoms:

- Progressive dyspnea

- Tachypnea

- Persistent, non-productive cough

Diffuse abnormalities in lung mechanics and gas transfer (restrictive pattern, PFTs)

Imaging (HRCT):

- Nodules

- Irregular lines

- Ground-glass opacities

Splanchnic mesenchyme

Supporting framework of the lung

- Fine elastic fibers

- Few fibroblasts

- Inflammatory cells

- Lymphovascular spaces

Fibrotic

- UIP

- NSIP (also cellular component)

- Pneumoconiosis (macrophage nodules in silicosis)

Granulomatous

- Sarcoidosis

- HP (also cellular component)

Alveolar filling

- COP

- DIP

- RB-ILD

- UIP

- NSIP

- Pneumoconioses

• Asbestosis
• Silicosis

- Subpleural/interlobular septal location

- Patchy, temporally heterogenous interstitial fibrosis

•  Dense fibrotic scars
•  Fibroblastic foci

Honeycombing (end stage lung disease)

- Drug toxicity

- Collagen vascular diseases

- Unknown

(idiopathic UIP=idiopathic pulmonary fibrosis, IPF)

HRCT of UIP (usual interstitial pneumonia)

- Subpleural disease with honeycomb cysts

Gross image of IUP

- Cobble-stone pleural surface due to scarring

- Subpleural process, patchy

- Primarily lower lobes

- Fibrosis, honeycomb

- Patchy interstitial fibrosis, remodeling

- Fibrosis subpleural, paraseptal and temporally heterogenous

• Dense fibrosis with remodeling/honeycombing
• Fibroblastic foci

- Chronic interstitial inflammation, mild-moderate

- Honeycombing

- Inflamed cystic spaces filled with mucin

- Lined by metaplastic bronchial cells

Microscopic findings in UIP

- Patchy fibrosis

- Subpleural distribution

Microscopic findings in UIP

Microscopic findings in UIP

End stage lung disease

- Dense collagenous scars result in lung remodeling

- Collapse of alveolar walls

- Formation of cystic spaces lined by epithelial cells, filled with mucus and inflammatory cells

- Histology does not conform to other ILD’s

- Temporally uniform

• Cellular (inflammatory) pattern
• Fibrosing pattern

- Most idiopathic

- Connective tissue diseases

- Occupational and environmental exposures

2 patterns, prognostically different

Cellular pattern

- Mild to moderate interstitial lymphoplasmacytic infiltrate (uniform distribution)

- Infiltrate involves alveolar interstitium

- Type II pneumocyte hyperplasia

- Lung architecture preserved

Fibrosing pattern

- Temporally uniform, diffuse (NO fibroblastic foci)

- Lung architecture preserved (NO honeycombing)

- Can see some chronic inflammatory cells

NSIP: cellular pattern

- Infiltrate on left

- Normal lung on right

NSIP: cellular pattern

- Interstitial infiltrate

- Architecture preserved

NSIP: cellular pattern

- Lymphoplasmacytic infiltrate

- Type II pneumocyte hyperplasia

NSIP: fibrosing pattern

- Temporally uniform fibrosis

Non-neoplastic lung reaction to inhalation of dust particles, chemical fumes, and vapors (occupational lung disease)

2 forms:

- Asbestos-related diseases

- Silicosis

Hydrated silicate fibers

- Amphiboles: straight fibers; association with mesothelioma

- Chrysotile: serpentine/curved fibers: primary form used in industry

- Asbestosis: bilateral diffuse interstitial fibrosis

- Fibrous pleural plaques

- Pleural effusions

- Mesothelioma: cancer of mesothelium (1000x’s compared to non-exposed)

- Lung cancer: 55 fold increase in lung ca (Asb + smoking) vs 5 fold increase (Asb alone)

- Bilateral diffuse interstitial fibrosis caused by inhalation of asbestos fibers

- Pattern of fibrosis is indistinguishable from other forms of ILD’s (need to see asbestos bodies)

- Primarily involves lower lobes

- Subpleural and parenchymal fibrosis

+/- honeycomb change (lower lobe disease)

Patchy interstitial and subpleural fibrosis (fibers stimulate release of mediators leading to repeated cycles of inflammation/fibrosis)

- Starts around respiratory bronchioles and alveolar ducts, proceeds distally

- Fibrosis similar to UIP Asbestos bodies (asbestos fiber + iron-protein coat