Question

What term is used to denote the replacement of alveolar epithelium by stratified squamous epithelium, seen on biopsy of a smoker's lung?

• A. Anaplasia
• B. Metaplasia
• C. Dysplasia
• D. Hyperplasia

Hint:

Chronic smoking classically causes squamous metaplasia, swapping respiratory epithelium for tougher squamous cells.

Answer 1

The Correct Option is B

The scenario describes one adult cell type in the lung being swapped for a different, tougher adult cell type in response to years of smoke exposure. That swap has a specific name in pathology.

1. Anaplasia: Describes cells that have lost their differentiation, typical of malignant tumours. It is not about one normal cell type being replaced by another.
2. Metaplasia: The reversible change of one differentiated tissue type into another differentiated type better able to handle the stress. Smoke driven replacement of respiratory epithelium by stratified squamous epithelium is the classic textbook example.
3. Dysplasia: Disordered, atypical growth within a single cell type, which can follow metaplasia if the irritant is not removed, but is a separate, more advanced change than the cell type swap itself.
4. Hyperplasia: More cells of the same original type, not a change to a different cell type.

Since the question describes one epithelial type being entirely replaced by another, tougher type, the fitting term is metaplasia.

Let's summarize:

• Metaplasia swaps one differentiated cell type for another, better suited one.
• Chronic smoking classically produces squamous metaplasia of the respiratory epithelium.

The correct answer is metaplasia.