Staining of paraffin sections of a second ALK-positive ALCL seen at low (left) and high (right) power (APAAP technique). As in the case shown in Fig 4, a clear difference is seen between the immunostaining for the C-terminal epitope (antibody NPMc) and an N-terminal epitope (antibody NPMa). Immunostaining for ALK is also shown. In the lower power view, the corresponding areas in three sections are shown. The asterisks indicate residual normal lymphoid tissue surrounded by tumor cells.