A modified Warthin-Starry procedure at low pH for melanin.

The Warthin-Starry argyrophilic silver stain peformed at pH 3.2 is a highly effective method for the demonstration of melanin in tissue sections. Eighty-five melanocytic tumors were studied using the Warthin-Starry and the Fontana-Masson procedures. The Warthin-Starry technic stained a greater number of cells in 68% of the tumors, with no loss of cellular detail. Twenty-three per cent of the tumors that appeared amelanotic on hematoxylin-and-eosin-stained sections were positive for melanin with the Warthin-Starry stain, but negative with the Fontana-Masson technic. The Warthin-Starry stain is more sensitive and specific for melanin than is the Fontana-Masson procedure.