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Hard Knee Lump Symptoms, Causes & Common Questions

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Last updated August 27, 2020

Hard knee lump questionnaire

Use our free symptom checker to find out what's causing your lump.

Are you experiencing a hard bump on the knee? Read more below to learn about six possible causes, questions your doctor may ask about your symptoms, and more.

Hard knee lump questionnaire

Use our free symptom checker to find out what's causing your lump.

Hard knee lump symptom checker

6 causes of a hard knee lump


A dermatofibroma is a common skin growth that usually appears on the lower legs, but may appear anywhere on the body. These growths are benign (noncancerous). Dermatofibromas are most common in adults and are rarely found in children.

Symptoms include a hard, raised growth that is red, pink, ..

Skin cyst

A cyst is a small sac or lump, filled with fluid, air, fat, or other material, that begins to grow somewhere in the body for no apparent reason. A skin cyst is one that forms just beneath the skin.

It's believed that skin cysts form around trapped keratin cells – the cells that form the relatively tough outer layer of the skin.

These cysts are not contagious.

Anyone can get a skin cyst, but they are most common in those who are over age 18, have acne, or have injured the skin.

Symptoms include the appearance of a small, rounded lump under the skin. Cysts are normally painless unless infected, when they will be reddened and sore and contain pus.

Diagnosis is made through physical examination. A small cyst can be left alone, though if it is unsightly or large enough to interfere with movement it can be removed in a simple procedure done in a doctor's office. An infected cyst must be treated so that the infection does not spread.

Rarity: Common

Top Symptoms: skin-colored armpit bump, marble sized armpit lump, small armpit lump

Symptoms that always occur with skin cyst: skin-colored armpit bump

Urgency: Wait and watch

Hard knee lump questionnaire

Use our free symptom checker to find out what's causing your lump.

Hard knee lump symptom checker

Synovial chondromatosis

Synovial chondromatosis is a disease affecting the synovium, which is a thin flexible membrane around a joint. It can often be confused with tendinitis and/or arthritis.

Rarity: Ultra rare

Top Symptoms: joint swelling, pain in one knee, pain in one hip, swollen knee, spontaneous knee pain

Symptoms that always occur with synovial chondromatosis: joint swelling

Symptoms that never occur with synovial chondromatosis: fever, night sweats, unintentional weight loss, warm red ankle swelling, warm red knee swelling, warm and red elbow swelling

Urgency: Primary care doctor


Warts, also called common warts or verrucae, are small, rough, rounded growths on the top layer of the skin. They may appear alone or in clusters. Common warts are caused by the human papillomavirus (HPV) and are contagious through direct contact. They may spread from one place on the body to another simply through touch.

Deep vein thrombosis

Deep vein thrombosis (DVT) is a blood clot that forms in a vein deep in the body. Most deep vein clots occur in the lower leg or thigh.

Rarity: Uncommon

Top Symptoms: fever, thigh pain, upper leg swelling, calf pain, butt pain

Urgency: Hospital emergency room

Benign bony growth (osteochondroma)

An osteochondroma is a non-cancerous growth that usually develops during childhood or adolescence. It is a benign tumor that forms on the surface of a bone near the growth plate.

Rarity: Ultra rare

Top Symptoms: lower leg bump, upper leg bump, numbness in one thigh, painful thigh lump, hip bump

Urgency: Primary care doctor

Hard knee lump questionnaire

Use our free symptom checker to find out what's causing your lump.

Hard knee lump symptom checker

Questions your doctor may ask about hard knee lump

To diagnose this condition, your doctor would likely ask the following questions:

  • What color is the bump?
  • Do you feel pain when you touch the bump?
  • Is your bump getting bigger?
  • Is there anything on the surface of the bump?

Self-diagnose with our free Buoy Assistant if you answer yes on any of these questions.

Hard knee lump symptom checker statistics

People who have experienced hard knee lump have also experienced:

  • 29% Knee Pain
  • 5% Swollen Knee
  • 3% Pain In The Outside Of The Knee

People who have experienced hard knee lump were most often matched with:

  • 100% Synovial Chondromatosis

People who have experienced hard knee lump had symptoms persist for:

  • 39% Over a month
  • 25% Less than a week
  • 15% Less than a day

Source: Aggregated and anonymized results from Buoy Assistant.

Hear what 1 other is saying
Painless bump below the knee cap.Posted January 9, 2021 by 6.
Hello, I'm 69yrs old and wish to give MY information of a recently discovered a 2" diameter Extruding BUMP right below my left knee cap. I don't know if any of this has anything to do with the appearance of said Bump but I've undergone 3 Major Shoulder Repair Surgeries in 10 months. Anyway, To describe the Medium Size (2" diameter) Bump RIGHT Below my Knee Cap. I only discovered my Bump one day as I kneeled down it felt as if my left knee wasn't sitting FLAT against the flat floor surface like normal. After I stood back up I pulled my pant leg up and found a round 2" diameter round Bump definitely protruding out that seemingly appeared overnight. I used my fingers, testing it, by pushing on it at different angles at different locations. Pressures and then actually pushed it around in all directions TRYING to find out if it were painful. After that initial feeling test I wanted to test the Bump by kneeling Directly down on it. With all my weight ONLY on that one affected knee, I found it was still not Painful but only slightly unsettling. It only felt strange in that the Bump feels like it gives and moves ALL without giving me any discomfort in the slightest...Basically, it just feels weird. There was absolutely no pain what so ever so I put it out of my mind and forgot about it with the mindset that it would eventually go away on its own. It's already been an amazing quick time-lapse of nearly 8 or 9 months since I first noticed it. I have to say that I really did forget it was even there. My bump still exists...Is Still NOT giving me any pain at all and doesn't affect any movement nor has it grown much, that I can tell. It presents no limitations or problems with getting dressed or with ANY other normal daily activities. I've been diagnosed with two different forms of Arthritis, Ostio and Rheumatoid so these may be a contributing factor or not. I mention it only that someone may find that information useful in some way. I mostly feel it's important mentioning that I've always been a very active male, Contact sports, Football, Soccer, Tennis, Cross-Country Running, Hiking, Hunting, Fishing, Snowmobiling, Dirt Bikes, Road Bikes, Bicycling, as well as other machines made for outdoor fun and just about ANY other physical outdoor activity you can imagine. I only point these out to show how active I've always been All my life. Certainly not trying to brag BUT only inserting as much background useful data for those possibly looking for any of MY data only. In Addition; For most of my adult life I've worked at several physically demanding jobs. Due to those demands, year after year, I've injured both knees more than a few times. Never to the point of needing surgical repair but the very typical and normal day or two of resting type. Just rest and good-to-go again, just like those... It never seemed like the bumps and bangs were ever that serious or that they needed attending by a Doctor. I can't say with any certainty but this may have some degree of possibility to do with the Bump that resides below my left knee cap. Once my shoulder Physical Therapy is concluded I will make time for an appointment with my Family Doctor to have him properly diagnose it. Since there is no pain I can only assume this is not life-threatening at this point so I don't feel any urgency to have it assessed right away. I only tell my story here for anyone else with the same symptoms or experience. Sometimes it's just comforting to know your situation isn't all that different. Call it a kind of misery loves company sort of kindred experience. Good luck to all of you and PLEASE don't take my situation or attitude of MY BUMP as Gospel. IF you are in the least at all concerned then you MUST have it checked out by a professional.... Listen to your body and go with what your brain is telling you to do...not what the guys will think. If it turns out to be nothing then at least you know and that's Always a good I right? If you have any pain associated with yours then Be Smart about it and have it diagnosed... Honestly people, Please do not take my experience to be at all similar to yours. Who knows, I may be doing more harm by delaying having mine checked out...I really don't know. I just don't want to be the cause for your, or anyone's Bump to get worse or have more serious consequences. My hope is to bring awareness from a first-person accounting and experience. Mine may not be typical or the correct thing for even me to be delaying, HOWEVER, if my contribution is in some small way may be helpful for you and more importantly may be useful for any actual experienced data for Physicians. Thanks, 69yr Old Guy

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