Medical Emergencies · patient case question
His chronic smoking has caused metaplasia of the respiratory epithelium. Into which epithelial type does the normal lining transform?
Patient case: COPD, a Black Tongue, and a Lateral Tongue Mass
Patient: 58-year-old male
Chief Complaint: “My tongue looks black and furry, and there’s a lump on the side of it.”
Background: Chronic obstructive pulmonary disease, GOLD stage III. 40 pack-year smoking history and still smoking one pack daily. Uses a chlorhexidine rinse intermittently. No cardiovascular disease.
Medications: Albuterol inhaler PRN · Tiotropium daily · Inhaled fluticasone
Vital Signs: BP 130/78 mmHg · HR 88 bpm · RR 22 · SpO₂ 92% on room air · T 98.4°F
Findings: Barrel chest, pursed-lip breathing, prolonged expiration. Dorsal tongue with markedly elongated, brown-black filiform papillae. A separate firm, nodular, exophytic mass approximately 15 mm across on the left lateral tongue, present for several months and slowly enlarging. Extensive restorative needs across three quadrants.
Show answer and explanation
Correct answer: A. Stratified squamous non-keratinized epithelium
- A. Correct. Chronic irritation converts pseudostratified ciliated columnar epithelium into stratified squamous epithelium, which resists mechanical and chemical insult far better. The cost is the loss of cilia and mucus-secreting goblet cells, crippling mucociliary clearance and predisposing to infection and to squamous cell carcinoma.
- B. Incorrect. Transitional epithelium (urothelium) is confined to the urinary tract, where it accommodates distension. It does not arise in the airway.
- C. Incorrect. Simple squamous epithelium forms the alveolar lining and vascular endothelium. A single flat cell layer would provide less protection, not more.
- D. Incorrect. Simple cuboidal epithelium lines the terminal bronchioles and renal tubules. It offers no protective advantage against smoke and is not the metaplastic endpoint.
Note: Metaplasia is by definition reversible — it regresses if the stimulus is removed. It is nonetheless a warning sign, since persistent irritation drives progression to dysplasia and then carcinoma.
Practice Medical Emergencies questions Medical Emergencies study notes