Pantone spot inks are used:
1) Where a job is only to be printed in 1,2 or 3 specific colours and
2) Where colours are required that are not available from CMYK printing. In
this case they will often be used in addition to the normal CMYK inks.
In Photoshop, reference to Pantone inks will only be retained when:
1) The image is a duotone file saved as Photoshop EPS or
2) Used in spot colour channels created from the channels palette and the
file saved as DCS2 EPS files.
In all other cases the Pantone will be converted ...