Ned is about my age. He came to see me about a year ago with swelling of one leg.
A few weeks after a steroid injection into his right hip, he noticed a gradual swelling of that leg. The hip felt fine. And Ned felt fine in general.
I examined him carefully and ordered what I think of as the usual tests when one leg is swollen and the other one isn’t.
Routine bloodwork and cardiac exam, venous Doppler of his leg, CT scan of his abdomen and pelvis were all normal. The orthopedic folks ordered an MRI of his swollen thigh. This showed the swelling of lymphedema but nothing else.
He got a compression stocking and carried on with his usual work and leisure activities.
Last month he got another steroid injection to the hip. A few weeks later, his lymphedema was almost gone.
I have not found anything like it in my search for answers. Has anyone else seen or heard about transient unilateral lymphedema, related to steroid injection or not?
One more instance of me confessing to my patient:
“I just don’t know.”
A Country Doctor Writes: 
very mysterious. possibly some unrelated event like minor trauma, insect bite ?
The answer to this is probably no, but does he have a history of travel to tropical regions? Could it be lymphatic filariasis?