I Have A Question Regarding A Knot In My Left

Question: I have a question regarding a knot in my left lower forearm in my left arm above my elbow.

When my arm is relaxed, the knot is barely visible. However, once I flex my biceps/forearm the knot stands out and it feels hard to the touch. The size of the knot is slightly larger than the size of a peanut. It does not hurt once touched. I do not have any other symptoms. I dont take any medication nor am I allergic to anything. I am 29 years old, weight 115 kg.

Having this knot for 3 months I went to my doctor in my primary care. She investigated the knot by touching it from different angles. She concluded that its not dangerous and not worth investigating further, but for safety sake she made another doctor which is her colleague to investiagate it aswell. They both concluded that it was not dangerous and that I should come back if it gets bigger. They said its likely a fat lump.

Also to mention, I do have another knot at around the same exact place in my right arm, however that knot is much smaller.

In essence, the knot is not bothering me in any way as it does not really stand in the way or anything nor does it really hurt. However once reading online about what it can be I got really worried about when i read about sarcoma. I maybe clueless, but should I be worry about that?

In what scenario should I be worried? Is it worth being super pre-emptive and pushing further to getting this investigated more or am I exgagerating?

Thanks for the answers Doctor, definately reassuring to hear.

I have a few additional follow up questions, more from the perspective of increasing my awareness and knowledge in this.

Firstly, in the event that this would have been a sarcoma, how fast would the other additional symptoms accrue? I.e, how fast would the bulge increase in size and diameter along with other symptoms?

Secondly, in the event of a sarcoma, would the actual texture of the knot/bulge change in relation to whether my arm is in a relaxed or a flexed state? To be more specefic, as mentioned previously if my forearm and biceps are in a relaxed state (meaning not flexed) the knot is barely visible and once touched it feels soft and smooth and moves around with the finger. However, once I fully flex my forearm and biceps, the knot becomes more pronounced and visible and it feels harder to the touch. Would this be the case if this was a Sarcoma or would the texture of the knot if this was a sarcoma be static? Meaning irregardles of wheter my arm is flexed/relaxed the knot would have the same texture?

Thirdly and lastly, as mentioned previously I have a similar knot (but much smaller in diameter) in the almost exact same place in my right arm. If this was a sarcoma, would the knot appear simultaneously at the exact same symmetrical place in the other arm? Or is the fact that another knot in the same symmetrical location in the other arm an ample indication that the origin of the knot is anatomic in nature and nothing malignant?

Would greatly appreciate an elaboration on all these 3 points as this would greatly increase my awareness and makes me more cautious on when & when not to be worried.

Thanks a lot in advance!