Esophagus - Babaei Flashcards
Desribe the measures taken by digestive epithelium to protect it from acid. (Hint: 2 classes)
Why is the esophagus susceptible to damage from acid?
Pre-epithelial defense: Secrete a mucus coating to obstruct activated pepsin, and bicarbonate ion to neutralize acid.
Epithelial defense: Intracellular buffering, acid extrusion processes, and structural barriers (membrane, stratification, tight junctions)
The esophagus lacks the described pre-epithelial defense.
Describe the pathogenesis of GERD.
Loss of LES tone causes and is exacerbated by esophageal acid reflux.
Damage from acid (and bile) induce IL-6, which increase H2O2, which increase PAF/PGE2, which reduces ACh and LES tone.
T/F: A LES tone of 0mm Hg will always produce gastroesophageal reflux.
True; the stomach is constantly under positive pressure.
Compare and contrast spontaneous (transient) LES relaxation and strain insufficiency.
In transient LES relaxation, the LES inappropriate relaxes, allowing reflux in the absence of increased gastric pressure.
In strain insufficiency, gastric pressure simply overcomes a usually weakened LES.
Describe the neural circuit that facilitates esophageal peristalsis.
Sensory stimulus is transmitted to the nucleus tractus solitarius. Motor efferent signals originating from the dorsal vagal nucleus (and/or nucleus ambiguus) control peristalsis by the postganglionic transmitters ACh and NO/VIP.
What controls the tone of the LES?
The LES is controlled by the same vagal circuit as the rest of the esophagus, but contributions are also made by the diaphragmatic crura. These are controlled by the respiratory center in the brainstem which signals along the phrenic nerves (cholinergic)
Give the type of hernia (I vs II) that matches the description.
- Para-esophageal
- Common
- Asymptomatic
- Associated with bowel sounds in lung field
- II
- I
- I
- II (from pathoma)
Describe the histologic appearance of injured esophageal tissue in GERD.
There is hyperplasia of the basal zone (regeneration secondary to injury) and elongation of the lamina propria papillae.
Eosinophilic, followed by neutrophilic infiltration.
Describe the gross appearance of injured esophageal tissue in GERD.
Redness and mucosal breaks (erosions) mainly in the lower 1/3 of the esophagus. The erosions have visible depth and may feature exudate.
Patients with GERD generally do not report symptoms until it progresses to reflux esophagitis. Describe the epidemiology of this disorder.
Usually affects older, obese adults. #1 cause of esophagitis, and #1 outpatient GI diagnosis in the US.
What are the 3 classic symptoms of reflux esophagitis?
What are 3 less common symptoms?
Heartburn (substernal, radiating retrosternally), regurgitation (feeling contents of stomach in throat), dysphagia.
Chest pain, chronic cough, hoarseness.
How is GERD diagnosed? When are these modalities indicated?
- Endoscopy (especially with alarm symptoms: dysphagia, anemia, weight loss, abdominal mass, vomiting)
- Ambulatory reflux monitoring (more sensitive than endoscopy)
(don’t bother with radiography)
How is GERD treated?
- Lifestyle modifications (weight loss, bed elevation, diet)
- Anti-secretory drugs (PPI > H2 blocker)
- Operative management (fundoplication, LINX?)
Name 4 possible complications of GERD.
Ulcer, stricture, bleeding, and Barrett’s Esophagus.
Describe how esophageal strictures are generated.
Chronic inflammation and scarring causes progressive dysphagia as the submucosa undergoes fibrous thickening and the muscularis propria atrophies.
Describe the pathogenesis of eosinophilic esophagitis.
T-cell mediated hypersensitivity reaction causes eosinophilic infiltration; subsequent deposition of MBP and IL-5/13 cause tissue remodeling/fibrosis.
Describe the clinical presentation of eosinophilic esophagitis. How are adults and children affected differently?
Adults experience dysphagia and food impaction (more often than nausea or heartburn)
Children experience nausea, burning, and food intolerance.
What are significant historical findings in the diagnosis of eosinophilic esophagitis?
A personal or family history of atopia (rhinitis, asthma, dermatitis)
Failure of acid suppressive treatment or symptoms of GERD without any actual reflux.
Describe the gross and microscopic findings needed to diagnose eosinophilic esophagitis.
Histologic: >15 eosinophils per HPF in esophageal mucosa.
Gross: Corrupted esophagus, “felinization”, longitudinal furrows, white abscesses.
How is eosinophilic esophagitis treated?
Since it is a hypersensitivity reaction, avoid allergen-rich foods (seafood, wheat, soy, nuts, milk, eggs). Topical & systemic steroids, endoscopic dilation.
What are the causes and possible consequences of chemical esophagitis?
Caused by ingestion of corrosives, alcohol, very hot fluids, and smoking, as well as lodging of pills in the esophagus (NSAIDs, Doxycycline, fosomax)
Consequences usually limited to pain, but also what naturally follows chemical injuries: hemorrhage, stricture, and perforation.
Distinguish between HSV and CMV viral esophagites.
HSV: Punched-out ulcers with nuclear inclusions at their rims (within epithelial cells).
CMV: Shallow ulcers with cytoplasmic AND nuclear inclusions (within capillary endothelium and stroma)
What agents are usually responsible for fungal esophagitis?
Candida is most common, but also mucor and aspergillosis.
How frequent is bacterial esophagitis?
Describe the nature of this infection.
Not common at all; only 10% of infectious esophagites.
Bacteria can invade the lamina propria and cause overlying necrosis. Primary or secondary to an existing ulcer.
What can cause iatrogenic esophagitis?
Describe its morphology.
Chemo, GVHD, radiation.
Generally non-specific; note that radiation causes blood vessel thickening >> ischemia.
What are the significance of diseases like Lichen planus, bullous pemphigoid, and epidermolysis bullosa in the context of esophageal pathology?
These are all conditions which usually affect the skin; many of the same epithelial components are present in the esophagus (or GI tract in general) and so they may have manifestations there.
Define:
dysphagia
heartburn
regurgitation
odynophagia
Dysphagia = difficulty swallowing
heartburn = burning feeling typically epigastric rising to the chest
regurgitation = effortless upward return of gastric contents
odynophagia = pain during swallowing and bolus transit
Differentiate esophageal vs. pharyngeal dysphagia
- Esophageal
- may have chest pain, may refer upwards to the throat
- ‘sticking’ or ‘hanging up’ after swallowing
- Pharyngeal
- difficulty initiating swallowing
- generally does not refer downwards
- coughing, choking, nasal regurgitation