As far as I know, pj stands for pajamas which are clothes consisting of pants and a top used for sleeping. I don't know what else "pjs" would stand for. Hope this helps.
What is pjs?
Peutz-Jeghers syndrome (PJS) is an inherited condition that puts people at an increased risk for developing hamartomatous polyps in the digestive tract as well as cancers of the breast, colon, pancreas, stomach, ovaries, and other types, listed below.