A modification of the Papanicolaou exfoliative cytology stain to demonstrate keratin in paraffin-block tissue sections.

A method of staining for keratin by application of a modified Papanicolaou staining procedure to formalin-fixed paraffin-embedded tissues is described. The modification is achieved by increasing the staining time for the three basic Papanicolaou stains and incorporating phloxine B as an additional staining component. Since the Papanicolaou staining components are common to most histopathology laboratories and phloxine B is not a rare stain component, this procedure can be instituted with a modicum of effort. The procedure is less time consuming than the usual staining methods for demonstrating keratin and does so with a high degree of reliability.