A patient who was a long-time heavy smoker was seen by a physician for a persistent cough. A biopsy of the bronchial lining displayed a change in the epithelium from pseudostratified ciliated columnar to stratified squamous. The patient decided to quit smoking, and a second biopsy 6 months later showed that a reversal had occurred in the epithelium; it was back to the normal pseudostratified ciliated columnar. This patient had

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The change in the bronchial lining from pseudostratified ciliated columnar to stratified squamous is a classic example of squamous metaplasia, which is a reversible change that can occur as a response to chronic irritation or inflammation such as that caused by tobacco smoke. The fact that the epithelium reverted back to normal after smoking cessation further supports the diagnosis of squamous metaplasia. Carcinoma or adenocarcinoma are not diagnosed based on biopsy findings alone, and bronchitis or pneumonia would not cause a change in epithelial type.

A Patient Who Was a Long-Time Heavy Smoker Was Seen