#Eosinophilic Lung Disease

## Simple Pulmonary Eosinphilia (Loeffler's Syndrome)

### Illness Script

#### Who does it occur in? 
Often have a history of atopic disease

#### How does it present? 
Blood eosinophilia
Mild dyspnea, cough
Transient / migratory areas of consolidation or ground glass, usually with ill-defined margins. Often predominantly peripheral distribution. May have nodules

#### How is it diagnosed?


## Acute Eosinophilic Pneumonia

###Illness Script:

#### Who does it occur in?

- 20-40 years old
- 2:1 male:female ratio. 
- Sometimes presents in people after they begin smoking (or vaping)
- Can be caused by daptomycin, venlafaxine

#### How does it present? 
 - Acute onset fevers, shortness of breath, hypoxemic respiratory failure

#### How is it diagnosed? 

- CXR abnormalities are non-specific, but similar to pulmonary edema (kerley b lines -> interstitial opacity -> air space consolidation, lower lobe predominance and bilateral)
- CT shows bilateral consolidation, interlobular septal thickening, sometimes with associated pleural effusion
- BAL with %eosinphils greather than 25% 

#### How is it treated

- responds within days to high dose corticosteroids, Rx'd for 2 weeks. 
- start after infectious pneumonia is excluded.
- sometimes remits on its own
- long term prognosis is excellent

## Chronic Eosinophilic Pneumonia

### Illness Script: 

#### Who gets it? 

#### How does it present? 
- Fever, cough, weight loss, malaise, dyspnea
- Blood eosinophilia
- Severe symptoms, last 3 months or more
- CT with patchy, peripheral, homogenous air space consolidation (photographic negative of pulmonary edema). Sometimes may have crazy paving. Similar to organizing pneumonia, without the basilar predominance. 
- remains unchanged (unlike Loeffler's) unless steroids given.

#### How is it diagnosed
- Lung biopsy, unless imaging findings are classic. 

#### How is it treated
Rapid resolution with steroids

## Hypereosinophilic syndrome

###Illness Script

#### Who does it occur in? 

#### How does it present
- Elevated blood eos for 6 months, multiorgan infiltration (morbidity from cardiac, cns involvement)
-If pulm involvement: cough, wheeze, SOB
- Hazy GGOs, pulmonary nodules 1cm or less in diameter in the peripheries on HRCT.

## Eosinophilic Granulomatosis with Polygangiitis

aka Churg-Strauss; extravascular granulomas and necrotizing vasculitis with eosinophils infiltrating various organs.

#### Who gets it?
- 40-50 years old
- often hx of atopic disease.

#### How does it present? 

- Allergic/prodromal phase: rhinitis, sinusitis, asthma
- Eosinophilic phase: Blood eosinophils over 10%, Lung (often resembles Loeffler's or chronic eosinophilic pneumonia) and GI involvement
- Systemic Vasculitis phase: "Polyangiitis", heart, skin, MSK, CNS, kidney also involved - fever weight loss, malaise occur.

CXR w/ Transient pulmonary opacities, +/- nodules/masses, hemorrhage, edema, effusion.

HRCT with consolidation/GGOs (60%), bronchial wall thickening or bronchiectasis (35%), septal thickening (5%)

Cavitation is less common than with GPA

#### How do you make the diagnosis

- send ANCAs (usually p-anca)
- eosinophils extravascularly 

#### How is it treated

- Usually respond to steroids

## Other eosinophilic lung conditions

- Drug reactions
- Parasite infections (Ascaris, Toxocara, Strongyloides), Tropical pulmonar eosinophilia
- Fungal disease (ABPA)
- Bronchocentric granulomatosis (necrotizing granulomas centered on bronchioles caused by hypersensitivity, upper lobe predominance)