panchromatic tends to refer to B&W film that responds to all colours not just green/blue (red insensitive, aka ortho film)...unless someone can correct me on this? You just develop it like any other film... however it does tend to be a more old fashioned term hence my idea that it's just *old* rather than exotic... besides, you can B&W slide (reversal process) out of nearly any kind of normal B&W negative film.
On the other hand, if he processed it in C-41 and found ANYTHING on it (like edge markings that say panchromatic), it's not B&W because C-41 bleaches out all the silver and B&W negative or positive processing film are *all* silver halides, if you run B&W through C-41 you come out with a strip of clear plastic. C-41 film has the image formed in "dye clouds" which are left behind after you strip out the silver stuff... this is what makes the image very dense when you only process it in B&W chemistry.
I'm not awake yet, i'm not sure any of the above makes sense
thinking about it, it could be a C-41 process B&W film. Wikipedia suggests that Panchromatic Film is a term used for B&W only, not colour, but if you can see edge markings after running it through c-41, it'd suggest this weird hybrid