I've heard of one clinic, the Pfeiffer Treatment Center in Illinois. Bruise mystery I have a bruise that's about 1.5 inches in diameter. There's a knot in the center, and this part is lighter in color. You didn't tell us where on your body the bruise is located or how you received it. A bruise appears when small blood vessels rupture under the skin, often following a bump or a fall.
Blood seeps into the tissue causing the discoloration.
The knot could be an injured vein. A tick or spider bite also may look like a bruise. If the bruise is very painful, develops an open sore, swells, drains or has red streaks coming from it, call your doctor. Also call your doctor if you develop fever or other flu-like symptoms. But again, it's hard to offer specific information without seeing the bruise or knowing how it got there.