Description_x000D_ Diagnostic Implications_x000D_ Fontana-Masson staining is used for the demonstration of argentaffin substances such as melanin, argentaffin granules and some neurosecretory granules. Staining patterns may be useful in cases of carcinoid tumors and melanoma._x000D_ Principle_x000D_ Argentaffin cells and melanin possess the ability to bind silver from a silver solution and reduce to visible metallic silver without the need for a reducing agent. The Fontana-Masson Stain Kit can be used for frozen or paraffin embedded sections.