33. Squamous metaplasia in bronchus

Staining: HE

Overview. The top bronchus is the best, so we’ll use mainly that.

Organ: Bronchi, lymph node

Description:

We can see two cuts of a bronchus and two pieces of a lymph node.

The top bronchus is the best, so we’ll use that. Cartilage and submucosal glands are present. In a small part of the bronchus is the epithelium stratified squamous.

The lymph nodes show anthracosis.

Diagnosis: Squamous metaplasia in bronchus

Causes:

• Smoking

Theory:

Cartilage and submucosal glands show us that we’re looking at a bronchus and not a bronchiolus.

Most of the epithelial is healthy, respiratory epithelium with goblet cells. Only a small part of the epithelium shows stratified non-keratinizing squamous epithelial metaplasia.

This type of metaplasia is characteristic in smokers and is a precancerous or preneoplastic lesion toward lung cancer.

Anthracosis in the lymph node

Normal respiratory epithelium – pseudostratified kinociliated columnar epithelium.

Close up of the top bronchus. Metaplasia has only occurred in a small part of the epithelium. Submucosal glands can also be seen.

The epithelium here is clearly not respiratory epithelium anymore, but stratified squamous epithelium instead