What is the morphology of asthma?

Morphology of Asthma

Microscopic Features (Histological Changes)

1. Airway Inflammation

   • Dense infiltration of:

     • Eosinophils (hallmark)

     • Mast cells

     • T lymphocytes

     • Macrophages

   • Peribronchial inflammation affecting submucosa and epithelium.

2. Epithelial Changes

   • Shedding of bronchial epithelium (denudation).

   • Goblet cell hyperplasia → increased mucus secretion.

3. Basement Membrane Thickening

   • Thickened subepithelial basement membrane due to collagen deposition, especially type III and type V collagen.

4. Smooth Muscle Hypertrophy & Hyperplasia

   • Increase in size and number of bronchial smooth muscle cells → contributes to bronchoconstriction.

5. Submucosal Gland Enlargement

   • Hypertrophy and hyperplasia of mucous glands → excessive mucus production.

6. Mucus Plugging

   • Lumen of the bronchi and bronchioles is filled with thick mucus, inflammatory cells, and debris.

7. Curschmann Spirals

   • Coiled, whorled mucus plugs containing shed epithelial cells are seen in sputum.

8. Charcot-Leyden Crystals

   • Crystals of eosinophil-derived proteins (e.g., major basic protein) are found in sputum or tissue sections.

Macroscopic Features (Gross Changes)

1. Hyperinflated Lungs

   • Lungs appear overexpanded due to air trapping (especially in severe or fatal asthma).

2. Mucus Plugs

   • Thick, sticky mucus plugs obstruct bronchi and bronchioles; they are visible on cut sections of the lung.

3. Pale and Puffy Bronchial Walls

   • Due to edema and inflammation.

4. Areas of Atelectasis

   • Some alveoli may be collapsed due to blocked airways.

5. No consolidation (usually) unlike bacterial pneumonia, asthma does not typically involve alveolar consolidation unless complicated.

 Summary Table

Feature	Microscopic Findings	Macroscopic Findings
Airway Inflammation	Eosinophils, mast cells, lymphocytes in bronchial walls	Thickened bronchial walls
Goblet Cell Hyperplasia	Increased mucus-secreting cells	Visible mucus plugs in airways
Basement Membrane	Thickened due to collagen deposition	Not visible grossly
Smooth Muscle	Hypertrophy and hyperplasia	Airway narrowing (noted during dissection)
Mucus	Excess production, Curschmann spirals, Charcot-Leyden crystals	Plugging of airways with thick mucus
Lung Appearance	-	Hyperinflated, pale, areas of collapse (atelectasis)