Metaplasia is the replacement of one differentiated somatic cell type with another differentiated somatic cell type in the same tissue. Typically, metaplasia is triggered by environmental stimuli, which may act in concert with the deleterious effects of microorganisms and inflammation.

What causes metaplasia?

Many medical experts consider intestinal metaplasia to be a precancerous condition. Although the exact underlying cause of intestinal metaplasia is unknown, there is a strong theory that the cause of the condition may be linked with a specific type of bacteria—namely, Helicobacter pylori (H. pylori).

Why does metaplasia occur in the lungs of smokers?

Squamous metaplasia (SQM) is a pre-neoplastic change of the bronchial epithelium observed in the lungs in response to toxic injury induced by cigarette smoke [1–4]. It is part of a multi-stage process [5–7] which may eventually lead to full neoplastic transformation, i.e. bronchial carcinoma.