Immunostaining of tissue sections previously stained with hematoxylin and eosin

S-100 protein was demonstrated in 28/31 melanoma tissue sections that had been previously stained by hematoxylin and eosin, including 17 from 19 primary melanomas and 11 from 12 metastases. Additional H & E stained sections from 11 metastatic and 13 primary melanomas were reacted with the monoclonal antibody NKI/C-3 and all stained positively. This approach is of value when additional sections are not available or when deeper cuts through a block do not contain tumor. The superimposition of the immunostaining does not reduce the record and diagnostic value of the double-stained sections.