Metaplasia and Dysplasia

A 58-year-old man with a 40-year history of smoking presents with chronic cough and hemoptysis. Bronchoscopy reveals a nodular lesion in the left main bronchus. Biopsy shows replacement of normal ciliated pseudostratified columnar epithelium with stratified squamous epithelium. The squamous epithelium shows increased nuclear-to-cytoplasmic ratio, irregular nuclear membranes, and coarse chromatin in scattered cells. What is the most likely diagnosis?

A 52-year-old woman with chronic gastroesophageal reflux disease (GERD) for 15 years undergoes upper endoscopy for persistent dysphagia. Endoscopy reveals a salmon-pink patch in the distal esophagus replacing the normal pale squamous mucosa. Biopsy from this area shows columnar epithelium with intestinal-type mucosa containing goblet cells, but the epithelium maintains normal architecture and uniform nuclear appearance. A biopsy from the proximal esophagus (normal-appearing area) shows normal stratified squamous epithelium. What is the most likely diagnosis in the salmon-pink patch?

A 58-year-old male smoker with a 30 pack-year history presents with chronic cough and hemoptysis. Bronchoscopy reveals a suspicious lesion in the left main bronchus. A biopsy shows columnar ciliated epithelium with mucin-secreting cells replacing the normal stratified squamous epithelium. Which investigation is most appropriate to assess the degree of malignant potential and guide further management?

A 52-year-old woman with a history of gastroesophageal reflux disease (GERD) for 15 years undergoes upper endoscopy for surveillance. Endoscopic biopsies from the distal esophagus show replacement of the normal stratified squamous epithelium with columnar epithelium containing intestinal-type glands with goblet cells. The mucosa appears grossly normal without visible ulceration or nodularity. Which investigation is most appropriate to assess the presence and grade of dysplasia in this Barrett's esophagus?

A 58-year-old male smoker presents with chronic cough and hemoptysis. Bronchoscopy reveals columnar epithelium with patches of stratified squamous epithelium in the bronchi. Which is the most common site of metaplasia in the respiratory tract?