Background: Surveillance of patients with Barrett's esophagus or ulcerative colitis for dysplasia is confined to biopsy specimens taken randomly during endoscopy because dysplasia remains undetectable by visual inspection. We attempted to visualize dysplastic tissue during endoscopy after sensitization with 5-aminolevulinic acid (5-ALA) leading to accumulation and formation of protoporphyrin IX and induction of characteristic red fluorescence of the latter substance using blue light illumination.
Methods: Six patients with histologically proven low- or high-grade dysplasia (Barrett's esophagus 2, ulcerative colitis 1, Billroth-II stomach 1, rectal polyps 2) were treated with oral administration of different concentrations of 5-ALA (10 to 20 mg/kg) or by local instillation of 3 gm 5-ALA in the rectum. Endoscopic fluorescence detection was performed 1 to 6 hours after sensitization using a blue light source and compared with conventional white light endoscopy. Biopsies of fluorescent and nonfluorescent areas were compared with histologic findings.
Results: Normal duodenal mucosa and squamous epithelium showed more intense 5-ALA-induced background red fluorescence compared with normal mucosa in the stomach or Barrett's mucosa. Histologically, dysplasia was exclusively found in areas with red fluorescence. False-positive fluorescence was associated with microscopic inflammation of the mucosa or feces in the colon.
Conclusions: 5-ALA-induced protoporphyrin IX fluorescence may be useful in the detection of dysplasia in the gastrointestinal tract by enhancement of endoscopic surveillance of patients at a high risk for dysplasia.