Hello!

Do you have photos that you can attach?  There are a number of diseases that affect Pachysandra, including recently introduced boxwood blight (oh joy), and the treatments vary depending on organism.  Given that three diseases that kill pachysandra look so similar, volutella, boxwood blight, and alfalfa mosaic virus, it may be necessary to send a sample to state college for a lab evaluation.

The treatment is usually removing, destroying, and not planting the same plant in its place.  Most of the pachysandras are vegetatively propagated so it is highly likely any pachysandra will be susceptible to the diseases.  More info will help!

Here are a few pictures of the pachysandra.

From looking at your pictures it seems to me that it is a fungus, Volutella, that is affecting your pachysandra. That first photo, the deading out, is especially what I've seen as volutella in the past. I've attached 3 photos of each of the diseases I've mentioned in the first response, starting with Volutella.

More information, including treatment, can be found here: http://www.missouribotanicalgarden.org/gardens-gardening/your-garden/help-for-the-home-gardener/advice-tips-resources/pests-and-problems/diseases/fungal-spots/volutella-blight.aspx