Eosinophilic Lung Diseases

Question 1

Types of eosinophilic lung disease (7)

Answer 1

1) Nonasthmatic eosinophilic bronchitis
2) Pulmonary eosinophilic syndromes
3) Hypereosinophilic syndrome
4) ABPA
5) Eosinophilic granulomatosis with polyangiitis (Churg-Strauss syndrome)
6) Drug-induced pulmonary eosinophilia
7) Helminthic infections (Loffler syndrome)

Question 2

Types of eosinophilic lung disease:
1) Nonasthmatic eosinophilic bronchitis

Answer 2

1) Nonasthmatic eosinophilic bronchitis
- Sx: chronic cough in non-smokers
- Ix:
Spiro: no airflow obstruction
Bronchial challenge test: PC20>16 (so no airway hypersensitivity)
- Sputum: >3% eosinophils
- Rx: ICS - improve Sx & sputum eosinophils

Question 3

Types of eosinophilic lung disease:
2) Pulm eosinophilic syndromes

Answer 3

2) Pulm eosinophilic syndromes
2.1: Acute eosinophilic pneumonia
- idiopathic, affect smokers, age 30s
- Sx: acute febrile illness <1m, dyspnoea, cough, myalgia, severe T1RF, blood eos normal
- Ix:
CXR: diffuse alveolar & interstitial infiltrates
BAL: eos >25% (ensure no evidence of fungal/ parasitic/ infection/ drug sensitivity)
- Rx: OCS

2.2: Chronic eosinophilic pneumonia
- idiopathic, middle-aged asthma females, can also be in non-asthmatics. MUST rule out parasitic infection (clarify travel Hx, endemic parasitic infection, drug, illicit drug use)
- Sx: gradually progressive SOB, cough, fever, LOW, wheezing, hypoxia, raised eos, raised inlam markers,
- Ix:
CXR: peripherally distributed pulm infiltrates
HRCT: more sens to show pulm infiltrates, mediastinal adenopathy
- Rx: OCS - improve Sx & pulm infiltrates

2.3: Loffler syndrome
- eos accumulate in the lungs due to parasitic infection (can be Ascaris, strongyloides)
- Sx: fever, rash, fatigues, wheezing, cough
- Ix: CXR, stool ova, cyst & c&S

2.4: Tropical eosinophilia
- occurs from a hypersensitivity response to microfilariae antigens, primarily those of Wuchereria bancrofti and Brugia malayi, present in the pulmonary microcirculation, which causes subsequent inflammation with eosinophils

Question 4

Types of eosinophilic lung disease:
3) Hypereosinophilic syndrome

Answer 4

• Dx: blood eos: >1500 for ≥6m with absence of underlying cause + end-organ damage from eosinophilia
• Causes:
  1) Idiopathic occurs at any age (usu 30s-40s), male
  2) Lymphoproliferative variant (from T-cells clonal expansion & IL-5 production
  3) Myeloproliferative variant (with fusion tyrosine kinase FIP1L1-PDGFRA
• Sx:
  Usu non-specific. Specific Sx depends on organ involved (40% involves lungs)
  In lung: cough, airflow limitation, spiro obstructive
  In cardiac: pulm fibrosis –> restrictive or mixed pattern on spiro
  Thromboembolic, nervous system
• Ix:
  CXR – normal or clearing airspace shadowing, non-segmental interstitial infiltrates, GGO
• Rx:
  1) OCS
  2) Lymphoproliferative variant - Mepolizumab
  3) Myeloproliferative variant – Imatinib (TKi)

Question 5

Types of eosinophilic lung disease:
5) Eosinophilic granulomatosis with polyangiitis (Churg-Strauss syndrome)

Answer 5

Eosinophilic vasculitis of small to medium-sized vessels

Question 6

Types of eosinophilic lung disease:
6) Drug-induced pulmonary eosinophilia

Answer 6

Causes e.g. Abx, antifungal, NSAIDs, anti-epileptic, antipsychotic, anticoag, allopurinol, MTX

Question 7

Types of eosinophilic lung disease:
7) Helminthic infections

Answer 7

• Causes: Ascaris lumbrocoides, Strongyloides, Schistosomiasis, Filariasis, Toxicara canis