Why Do I Have a Thin Dark Line Down my Laugh Line Which Was Filled with Juvederm Ten Days Later? (photo)

Posted photo of NO help! So very hard to advise over the internet. You could seek for a fee a second opinion in person. 

The Tyndall Effect or blue light scattering is a well-known complication of injecting hyaluronic acid fillers too superficially in the skin. Belotero Balance, a relative newcomer in the U.S., owing to the special method of its manufacture, has little tendency to give rise to this problem even when injected superficially. For this reason, it has become my favorite for improving very fine lines and wrinkles after other volumizing agents have been used to improve the deeper component of the wrinkles and furrows. Diluting other fillers, such as Juvederm, has also been used for treating fine wrinkles and superficial lines with good effect and with little resulting problem of bluish discoloration.

Unless treated with hyaluronidase to degrade the injected material quickly, the Tyndall effect may persist for many months until the body naturally digests all the injected hyaluronic acid.

Of course, bruising from the injections themselves can also be the cause of a bluish discoloration. These, as is the case with all kinds of bruises, tend to fade on their own after only a few days. Going forward, consultation with a board certified aesthetic physician with extensive experience with all the available injectable materials is highly recommended.

The photo does not show it, but from your description I would suspect it could be caused from the Juvederm being injected superficially in that line.  It could be from bruising but people can get a "Tyndall effect" (bluish color) where the product is injected too superficially.  This could last months because Juvederm breaks down very slowy.  If you are very unhappy with the results,  you can have some Hyaluronidase injected to dissolve the product including the "lump" of Juvederm.  I doubt you have a granuloma.  It's more likely excess product trying to correct the deep line.  I have sometimes found going across the line instead of injecting vertically in the line will help lift and support the area at the low end on the laugh line without having to add too much product.  Give it a bit more time and massage the "lump" first to see if this can help. Good luck