A patient with long-standing gastroesophageal reflux undergoes endoscopy; biopsy of the distal esophagus shows replacement of stratified squamous epithelium by intestinal-type columnar epithelium with goblet cells. Metaplasia here occurs primarily through which mechanism?

• A Direct transdifferentiation of mature squamous cells into columnar cells
• B Reprogramming of local stem cells along a different differentiation pathway ✓
• C Migration of gastric mucosal stem cells upward into the esophagus
• D Neoplastic clonal expansion of mutated basal cells

Explanation

Metaplasia arises when persistent injury alters the differentiation program of progenitor or stem cells present in the tissue, so they generate a cell type better able to withstand the stress; it is adaptive, reversible if the stimulus ceases, but carries increased risk of malignant transformation. Mature squamous cells do not switch lineage themselves, and Barrett esophagus is a premalignant adaptive process, not yet a neoplasm.

Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.