I have a bone cyst in my little finger on the left hand- middle bone. I have had it for 25 years & they are really nothing to be concerned about!
However, they can be a real nuisance. They are quite benign- just cartilage type material instead of hard bone therefore much less structurally sound!
My cyst is quite large & occupies most of the bone- I have broken that bone twice because of the weakness in it, & have had surgery twice to scrap out the cyst in the hope that stronger bone will grow. The cyst is still there however & I have learnt to be defensive & not put that hand out if I fall or stumble!
Keep an eye on it- if it grows it could make the bone look disproportionately big & therefore fragile because the boney outer shell will become thinner. Otherwise just leave it- but be careful not to knock that part of the foot or drop anything on it- because it is certainly less strong than it should be!