Ulcerated Scars and Hyperpigmentation After Sclerotherapy

Ulceration was more likely in the past where high concentration sclerosant solutions were used, such as 21% hypertonic saline. Remember that physiologic saline solution that is given intravenously while you are hospitalized is 0.9% whereas hypertonic saline is 23 times more concentrated. When this solution is extravasated into the skin outside of the vein, it causes skin necrosis.I no longer use hypertonic saline for sclerotherapy. I use FDA approved sclerosants which have a very very low likelihood of causing skin necrosis. Having said that, every sclerosant solution has associated risks when used for sclerotherapy - infection, hyperpigmentation, thrombophlebitis, DVT ... Discuss further with the vein specialist before sclerotherapy is planned. 

sometimes too much of a sclerosant is injected or too much pressure used or too strong a concentration can cause these "ulcers" to form.

every physician who treats veins has had this happen, and it really depends on the patient being treated.  some are just more prone to this occurring.  it can be minimized by using small injection doses, weaker solutions, and low injection pressures.

This most likely is due to hemosiderin deposition. Usually the body will absorb this over time, but obviously this has not been the case in your situation.
I would recommend a combination of Auriderm and Tazarac cream. Please be aware Tazarac is a Category X and should not be used if there is a chance you might become pregnant.