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NBME 24 Answers

nbme24/Block 2/Question#50

An obese 57-year-old man comes to the physician for ...

Normal ciliated columnar epithelium replaced by normal squamous epithelium

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submitted by lsmarshall(200),

Metaplasia - A reversible adaptive response in which there is "Reprogramming of stem cellsŽreplacement of one cell type by another that can adapt to a new stress." Both are normal cells. Respiratory tree should not have squamous cells until respiratory bronchioles (before that; cuboidal in term. bron. > columnar in bronch. > pseudostratified columnar in large. bronch.).

shayan  if its a metaplasia, then how it be normal ? I mean Metaplasia is not normal? +  
artist90  i got it confused bc the question stated that there was a mass in one lobe of lung and i didn't knew that squamous metaplasia also presents as a mass in lung. i missed that on biopsy they were clearly stating squamous metaplasia. +1  

This could easily be confused with Squamous Cell Carcinoma as they are describing a mass. But i think the key difference is that they mention METAPLASIA. If it was dysplasia, then it would have been cancer.