HRCT Interstitial Pneumonia

UIP or IPF DIP NSIP EAA or HP RB and RB-ILD BOOP or COP

Six diseases

A simplified way to remember the HRCT patterns…

HRCT Features Location Clinical features Specific points about each disease

Secondary Pulmonary Lobule

Line drawing of a secondary pulmonary lobule.

Borders of lobule are interlobular septa.

At center of each lobule is a bronchiole and a pulmonary artery (blue).

Pulmonary vein (red) run in interlobular septa.

Lymphatics (green) are found in interlobular septa and in central or axial interstitium that surrounds bronchovascular bundles.

Secondary Pulmonary Lobule

artery

veinslymphatics

bronchusacini

pleurachest wall

Secondary Pulmonary Lobule

Secondary Pulmonary Lobule

Artery

Bronchus

Vein Lymphatic

HRCT Signs

GGO – see underlying architecture Consolidation – obscures underlying

architecture Reticulation – septal thickening (lacy

appearance Honeycombing – lung destruction Traction bronchiectasis Nodules – centrilobular or random

Secondary Pulmonary Lobule

Secondary Pulmonary Lobule

UIP clinical features

Middle aged to elderly Insidious onset Progressive sob & cough Bad prognosis – mean survival 5-6

years Poor response steroids – incomplete

recovery

UIP HRCT findings

Septal thickening +++ Honeycombing +++ Traction bronchiectasis + Ground glass opacity + Consolidation +

UIP location

Peripheral / sub pleural Basal – lower lobes Posterior

Case 1

Case 1

Case 1

Case 2

Case 2

Case 3

Case 4

Case 4

Case 4

DIP clinical features

Uncommon Insidious onset 90% are smokers Dyspnea and dry cough Good prognosis Good response steroids – complete

recovery possible

DIP can be secondary to...

Drugs Histiocytosis Leukemia Asbestosis Hard metal pneumoconiosis

DIP HRCT findings

Ground glass opacity +++ Reticulation + Traction bronchiectasis + Centrilobular emphysema – association

with smoking

DIP location

Peripheral / sub pleural Basal Posterior

Case 1

Case 1

Case 1

If you see GGO…

Normal expiration Partially filled alveoli Partially collapsed alveoli Alveolar wall thickening Interstitial thickening Increased capillary blood volume

If you see GGO…

Pneumocystis / pneumonia AIP / ARDS Inflammation - CTD / sarcoid / PAP Radiation pneumonitis Pulmonary edema / hemorrhage Fibrosis - UIP / NSIP DIP / RB-ILD / COP BAC

NSIP clinical features

Diagnosis of exclusion – CTD / HP Middle aged to elderly Insidious onset Dyspnea and dry cough Good prognosis Good response steroids – complete

recovery possible

NSIP HRCT findings

Reticulation +++ Traction bronchiectasis +++ Ground glass opacity +++ Consolidation ++

NSIP location

Peripheral / sub pleural May be basal

Case 1

Case 1

Case 2

Case 2

Case 2

Case 2

NSIP

If you see any honeycombing it is probably UIP

Chronic HP is in the differential diagnosis of NSIP (along with everything else!)

NSIP

NSIP

NSIP

EAA (HP) clinical features

Allergic disease inhalation of antigens in organic dusts

Thermophilic actinomycetes – farmers lung

Acute – fever chills dry cough dyspnea Progression to subacute and chronic

with repeated exposure Remove antigen, steroids

EAA (HP) HRCT findings

Patchy Ground glass opacity +++ Centrilobular nodules +++ Mosaic attenuation on inspiration Lobular areas of air trapping on

expiration Chronic EAA - GGO, reticulation,

traction bronchiectasis and honeycombing

EAA (HP) location

Patchy distribution Subacute EAA mid and upper lungs No zonal distribution Chronic EAA often spares the

costophrenic recesses and mimics NSIP

Case 1

Case 1

Case 1

Case 1 - Expiration

RB-ILD clinical features

RB usually has no clinical signs Young adult smokers Insidious onset Progressive dyspnea and chronic

cough Good prognosis Good response steroids - complete

recovery possible

EB / RB-ILD HRCT findings Centrilobular nodules poorly defined Multifocal ground glass opacity Thickened bronchial walls May see reticulation in lower lungs May have centrilobular emphysema

RB /RB-ILD location

Diffusely distributed Upper and mid lungs mainly

Case 1

Case 1

Case 1

Case 1

Case 1

Case 1

If you see centrilobular nodules… EAA or HP (ask about exposure) RB or RB-ILD (ask about smoking) COP (BOOP) CWP, silicosis Histiocytosis, Endobronchial TB Bronchiectasis, BO, CF ABPA, Asthma

If you see centrilobular nodules… Pulmonary edema Pulmonary hemorrhage Vasculitis Asian panbronchiolitis Endobronchial spread of tumor –

bronchoalveolar cell carcinoma

COP (BOOP) clinical features Several month history Non productive cough Low grade fever, malaise, dyspnea Good prognosis Good response steroids – complete

recovery possible

COP (BOOP) HRCT findings Patchy consolidation +++ Patchy ground glass opacity ++ Small ill defined nodules + Large nodules or masses + Bronchial wall thickening +

COP (BOOP) location

Sub pleural Peribronchovascular Sometimes affects the lower lungs

more

COP like reaction….

Drug reactions Pulmonary infections Collagen vascular diseases Wegener`s granulomatosis Toxic fume inhalation

Case 1 Not HRCT

Case 1 Not HRCT

Case 2 Not HRCT

Case 2 Not HRCT

Case 3 Immunosupressed

Case 3

The sequel of AIP

Questions to ask yourself upon seeing HRCT… Age and gender Acute or chronic symptoms Smoking, systemic disease (CTD) Old studies (best friend) What are the HRCT findings? Where are the HRCT findings? Differential diagnosis of above