[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [General pathology](https://durgical.com/en/general-pathology/) › [Lung](https://durgical.com/en/general-pathology/areas/lung/) › Asthma: pathology

# Asthma: pathology

- Lesion

Asthma is chronic airway inflammation that makes bronchi narrow in episodes. Over time the airway wall thickens and part of the narrowing becomes fixed.

Updated Nov 12, 2026

## Key points

- Atopic: childhood onset, family history, other allergy (rhinitis, eczema), positive skin tests, high IgE.
- Th2 cytokines: IL-4 (IgE switch), IL-5 (eosinophils), IL-13 (mucus, IgE); ILC2 cells add the same cytokines.
- Early phase (minutes): mast-cell mediators cause bronchospasm, mucus and leakage. Late phase (hours): eosinophils, neutrophils, T cells.
- Sputum: Curschmann spirals (mucus casts), eosinophils, Charcot-Leyden crystals (galectin-10).
- Remodeling: sub-basement membrane fibrosis, gland and goblet-cell enlargement, smooth muscle hypertrophy and hyperplasia, more vessels.
- Aspirin-sensitive asthma: with nasal polyps and rhinitis; COX inhibition shunts arachidonic acid to leukotrienes.

On this page

- The basics Key points
- What it is
- Structure
- Step by step
- Types of asthma by trigger
- Markers
- Memory aid
- Elsewhere in DurgiPedia

- Clinical Clinical notes

- Study Test yourself

- Connections Connections

## What it is

Asthma is a chronic inflammatory disease of the airways with variable, largely reversible obstruction: episodes of wheeze, breathlessness, chest tightness and cough, often at night. The commonest form, atopic asthma, is a Th2- and IgE-driven type I hypersensitivity reaction to inhaled allergens. Repeated inflammation remodels the bronchial wall, which explains the fixed component some patients develop.

## Structure

- Fatal attack (gross): overinflated lungs with small atelectatic areas; bronchi and bronchioles plugged by thick, tenacious mucus.
- H&E: thickened basement membrane zone (subepithelial collagen), many eosinophils in the mucosa, goblet-cell hyperplasia, enlarged submucosal glands.
- Hypertrophied and hyperplastic bronchial smooth muscle; increased vascularity; edema.
- Sputum or lavage: eosinophils, Charcot-Leyden crystals and Curschmann spirals.

## Step by step

- In a genetically prone person, inhaled allergen is presented to T cells that become Th2 cells (epithelial IL-33 and TSLP push this).
- IL-4 and IL-13 switch B cells to IgE, which coats mast cells.
- On re-exposure, allergen cross-links IgE on mast cells: histamine, leukotrienes C4–E4 and prostaglandin D2 are released.
- Bronchospasm (direct and through vagal reflexes), edema and mucus narrow the airway within minutes.
- Hours later recruited eosinophils release major basic protein and cationic protein that damage the epithelium.
- Repeated cycles thicken the wall (remodeling), adding a fixed component to the obstruction.

## Types of asthma by trigger

| Type | Mechanism | Clues |
| --- | --- | --- |
| [Atopic](https://durgical.com/en/conditions/asthma/) | Type I (IgE) hypersensitivity, Th2 | Childhood, family history, eczema, positive skin tests |
| Nonatopic | No allergen sensitisation; airway hyperreactivity | Viral infections, pollutants, cold, exercise as triggers |
| [Drug-induced (aspirin and NSAIDs)](https://durgical.com/en/conditions/chronic-rhinosinusitis-and-nasal-polyps/) | COX block, fall in PGE2, excess leukotrienes | Nasal polyps, rhinitis, urticaria |
| Occupational | Type I or direct release of bronchoconstrictors | Fumes, resins, wood or cotton dust, formaldehyde at work |

## Markers

- Charcot-Leyden crystals
- Curschmann spirals
- Blood eosinophilia
- Raised IgE

## Clinical notes

- Attacks of wheeze, cough and dyspnoea, often at night or early morning, triggered by allergens, viral infections, cold air, exercise or irritants.
- Acute severe asthma can be fatal; most patients live a normal life between episodes.
- Blood eosinophilia and high IgE support atopic asthma; type 2 biologic therapies target IL-5, the IL-4 receptor or TSLP.
- Neutrophil-rich, steroid-resistant asthma is a Th17-related minority.

## Memory aid

Four IL-ments of asthma: IL-4 makes IgE, IL-5 calls eosinophils, IL-13 makes mucus; leukotrienes squeeze.

## Test yourself

Think of the answer, then tap the question to see it.

## What are Charcot-Leyden crystals?

Crystals of galectin-10 released by eosinophils, seen in the sputum of patients with atopic asthma.

## What is airway remodeling in asthma?

Structural thickening of the bronchial wall: sub-basement membrane fibrosis, larger glands and more goblet cells, smooth muscle hypertrophy and more vessels.

## Why can aspirin trigger asthma in some patients?

Blocking cyclooxygenase lowers prostaglandin E2 and shunts arachidonic acid toward bronchoconstricting leukotrienes.

## Which cytokine recruits and activates eosinophils in asthma?

IL-5, secreted by Th2 cells and group 2 innate lymphoid cells.

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[More Pathology questions →](https://durgical.com/en/practice/?f=pathology)

## Elsewhere in DurgiPedia

- [Type I hypersensitivity (immediate, IgE)](https://durgical.com/en/immunology/type-i-hypersensitivity/)
- [IL-4, IL-5 and IL-13 (the Th2 cytokines)](https://durgical.com/en/immunology/il-4-il-5-and-il-13/)
- [Mast cell and basophil](https://durgical.com/en/immunology/mast-cell-and-basophil/)
- [Th1, Th2, Th17, Tfh and Treg](https://durgical.com/en/immunology/th1-th2-th17-tfh-and-treg/)

## Connections

## Related 6

- [Chronic bronchitis](https://durgical.com/en/general-pathology/chronic-bronchitis/)
- [Bronchiectasis](https://durgical.com/en/general-pathology/bronchiectasis/)
- [Pulmonary eosinophilia](https://durgical.com/en/general-pathology/pulmonary-eosinophilia/)
- [Rhinitis, sinusitis, pharyngitis and tonsillitis](https://durgical.com/en/general-pathology/rhinitis-sinusitis-pharyngitis-and-tonsillitis/)
- [Mediators of inflammation: the table to know](https://durgical.com/en/general-pathology/mediators-of-inflammation-the-table-to-know/)
- [Arachidonic acid metabolites in inflammation, and the drugs that block them](https://durgical.com/en/general-pathology/arachidonic-acid-metabolites-in-inflammation-and-the-drugs-that-block-them/)

## Related conditions 2

- [Asthma](https://durgical.com/en/conditions/asthma/)
- [Allergic bronchopulmonary aspergillosis (ABPA)](https://durgical.com/en/conditions/allergic-bronchopulmonary-aspergillosis/)

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Educational content on the mechanisms of disease; not a diagnostic or treatment guide and no substitute for a health professional's advice. No doses are given.

Sources: [Asthma](https://medlineplus.gov/asthma.html) (MedlinePlus, US National Library of Medicine, 2025).

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Representative model, for educational purposes only.

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License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/general-pathology/asthma-pathology/