Endoscopic Tattooing: From Blue to Black

CASE REPORT A 66-year-old female underwent a colonoscopy for evaluation of diarrhea. Two polyps were seen (10 mm and 20 mm) in the ascending colon. Due to poor preparation in the right colon, a polypectomy was not pursued. Because the lesions were hard to identify, 2 tattoos were placed 3 cm distal to each polyp. It was discovered that instead of Endomark (PMT Corporation, Chanhassen, MN), undiluted methylene blue was injected in the submucosa (Figure 1). Eight days later a repeat colonoscopy was performed to attempt polypectomy. Two deep, necrotic, exudate-covered ulcers were at the site of the tattoos, each measuring about 20 mm (Figure 2). No bleeding was present. The polyps were successfully removed with saline injection snare