Asthma

discussion on the pathogenesis, microscopy and gross findings of asthma.

1. Asthma - Pathogenesis Dr Tamil Nila II year postgraduate Department of Pathology

2. What is Asthma? Heterogenous disease Chronic airway inflammation Expiratory airflow obstruction Symptoms Wheezing Shortness of breath Chest tightness cough

3. Major subtypes Atopic Asthma Type 1 hypersensitivity Childhood Environmental allergens Positive family history High total serum IgE levels Serum radioallergosorbent tests Non Atopic asthma No evidence of sensitization Less common family history Associated with Viral respiratory infections Air pollutants Cold

4. Major subtypes Drug – Induced asthma Aspirin sensitive asthma NSAIDs Associated with utricaria Occupational asthma Fumes Dusts Chemicals Even minute quantities are sufficient Repeated exposure

5. Pathogenesis Th2 responses, IgE and Inflammation Genetic susceptibility Environmental factors

6. Th2 responses, IgE and Inflammation

7. Triggering of Asthma

8. Early Phase Bronchoconstriction Increased mucus production Vasodilation Vascular permeability

9. Late Phase Recruitment of Leucocytes Eosinophils Neutrophils More T cells

10. Mediators

11. Genetic susceptibility Chromosome 5q Gene cluster encoding for IL 3, IL 4, IL 5, IL 9, IL 13 & IL 4 receptor Class II HLA alleles Genes encoding IL 33 Thymic stromal lymphoprotein

12. Environmental factors Industrial Air pollutants Hygiene hypothesis

13. Normal vs Asthmatic Airway

14. Gross Hyperinflated lungs Occlusion of bronchi by thick, tenacious mucus plugs

15. Microscopy Airway wall thickening Eosinophilic inflammation Goblet cell hyperplasia Muscle hypertrophy Sub basement membrane fibrosis Increased vascularity Increased size of submucosal glands

16. BAL Wash findings Curschmann spirals Charcot leyden crystals

17. References Robbins and Cotran pathologic basis of disease Autopsy pathology – A manual and atlas, Andrew J. Connolly Comprehensive Cytology, Marluce Bibbo