Close
The lazy way is to just use Surface Blur (and optionally History Brush afterward to repair any detail loss).

That scan is already very smoothed/blurred already so it may not be a bad idea to apply Surface Blur earlier in the de-noising process as it doesn't get along very well with ultra-soft blurry edges. If you have decent edges Surface Blur can usually make them more refined (sharper), but if they are blurry and faint it will do the opposite and erase them so you have to be careful.

Lazy example with Photoshop Surface Blur:
http://cyberbeing.extra.hu/girls-of-summer001-copy4.png

Lazy example with NeatImage Plug-in (Home+ $50 or Pro+ $75):
http://cyberbeing.extra.hu/girls-of-summer001-copy5.png

Lazy example with NoiseNinja Plug-in (Home Bundle $45 or Pro Bundle $80):
http://cyberbeing.extra.hu/girls-of-summer001-copy6.png