Well, I can see two super simple options:
-Create the dark "base" material, then plug a map with some white spots to the self illumination slot
-Create the "dark "base" material, then plug a map with some black spots to the opacity slot. Then place a simple Corona Light above this plane.
The 1st method will give you some small illumination, but it probably won't be even visible in the render.
The 2nd option may give you some illumination from the light, so it may be the slower/worse one.