Was playing casually, got ok gear, found a lab. And for my surprise on descending I’ve got overwelmed by flying messages that I’ve got badly damaged by unknown force. I realized that I was standing on a DISSECTOR. The funny (or rather scary) thing is I have to step onto dissector again to go upstairs 
There are stairs shown on dissector tile and it is the only way to get out. (unless I’ll find a teleporting device or dig upstairs)
I would debug out the dissector, or debug stairs in on the same map tile. Lab mapgen is weird.