CMC Boss Hand Hand Pain Lumps and Bumps

How to Know if You Have a CMC Boss

A carpometacarpal boss, also known as a CMC boss or “bossing,” is a lump that appears on the back of the hand. It is typically in line with the pointer or middle finger. The exact cause of it is unknown, although sometimes they can arise from a traumatic injury or repetitive wrist motion that can happen during things like golf.

Here are some signs that you have a CMC boss:

  • You notice a lump on the back of your hand
  • It appeared between the ages of 20 and 40
  • You feel pain when moving the wrist up or down
  • You feel a snapping sensation when moving the wrist

It is important to note that not all CMC bosses are painful. Some people will feel nothing at all. Others will feel tenderness over the lump. Many will mistake a CMC boss for a Ganglion Cyst, which can look similar. Learn more about Ganglion Cysts.

If your CMC boss is not painful, you don’t need to do anything. Simply leaving it alone will not cause any harm. If your boss is painful, treatment options may vary. You may need a splint, medication or surgery. You may also simply need to ice the area. Find a hand surgeon near you to discuss the best treatment option for you if you are living with a painful CMC boss.

Learn more at

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  • Luana McPherson
    May 11, 2019 at 5:37 PM

    I have a vein on the inside of my wrist that is bulging and running up my hand into my palm and down below the wrist into the vessels running into my arm. I just noticed it last night and it has expanded since then.

  • Aashish pradhan
    August 14, 2018 at 10:42 AM

    I have big lump on the back side of my hand ,near wrist area,I have noticed it’s growing slowly ,is it cancer or just a fluid collection

  • June 2, 2017 at 3:56 AM

    great information.

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