Preparations for magnifying observation. (a, b) Pronase MS. Washing of the target lesion surface can be done with 500 cc of lukewarm water containing a packet of Pronase MS (20000 U). (c) Indigo carmine (Daiichi Pharmaceutical Corp., Tokyo, Japan). (d) The dye is a blue stain that accentuates the contours of a lesion, providing a detailed view of its border and shape. The dye is used as a 0.1–0.4% aqueous solution. (e) This solution is flushed through the biopsy channel of the scope using a 20-cc syringe. Generally, 3–5 cc is delivered in 5 s along with 15 cc of air. (f) Crystal violet (Honzo Pharmaceutical Corp., Nagoya, Japan). The dye is a vital stain and is preferentially taken up by the Lieberkuhn gland openings (crypts), which appear as dots or pits. (g) A few small drops of crystal violet in 0.05% solution are applied using a nontraumatic catheter (Olympus 6233064; Olympus Optical Co., Ltd., Tokyo, Japan).
