Four weeks after my op (RARP on 26th Jan 2017) I had an uncomfortable lump in my groin, in the next 24 hours my left leg became very swollen. Walking was eye wateringly painful. I was admitted (A&E) and was diagnosed with a lymphocele in my abdomen. After 4 days (Friday to Monday (it was a weekend!!)) I was given the option of draining or nothing. I opted for draining. That afternoon I was told (by a junior doctor) that I should walk (take pain killers and walk through the pain). I did that and the next morning my leg swelling had reduced. I was discharged that day as they believed it would correct itself.
Over the following days I walked and walked further each day with less pain killers and less pain each day and after a week I was pain free. Five weeks later . . . . . my left leg (thigh) is just 1cm bigger than the right leg and I have a volume of water (?) in my pubic area. I also notice that I have a (painless) swelling in my groin. I saw the surgeon 2 weeks back who said words along the lines that "you've had it worse than others but hopefully it will all settle down." I see him again next week.
I don't know what happened or what's happening but I suspect that when they were slicing through my bits they sliced through some of the pathways that lymph fluids use to get from A to B.