<s>[INST] After a 1.5 hour flight, a sudden lump developed on my calf. It was very painful and swollen. I rubbed it until until the lump went away and then a huge red bruise developed. The next day there was a large, round, red bruise and in the center the skin was back to its normal color and the bump was gone. Thoughts? Age 68. [/INST] thanks for sharing your health concerns with us!well, it seems that it could be some engorged vein or a lymph channel! however, could be some bursa or sebaceous cyst also...not to worry much...if you are worried much a USG with doppler TEST IS THE BEST WAY TO CONFIRM IT! ...... all the best......! </s>