Read below about painful knee lump, including causes and common questions. Or get a personalized analysis of your painful knee lump from our A.I. health assistant. At Buoy, we build tools that help you know what’s wrong right now and how to get the right care.

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A.I. Health Assistant Causes for Painful Knee Lump

The list below shows results from the use of our A.I. Health Assistant by Buoy users who experienced painful knee lump. This list does not constitute medical advice.

  1. 1.Baker's Cyst (Popliteal Cyst)

    A Baker's cyst, also called as Popliteal cyst, is a fluid-filled mass that causes a bulge and a feeling of tightness behind the knee. The pain can get worse when the knee is fully flexed or extended.

    Recovery with nonsurgical treatment varies

    Rarity:
    Uncommon
    Top Symptoms:
    calf pain, swollen knee, knee pain that gets worse when squatting, knee instability, dull, achy knee pain
    Symptoms that always occur with baker's cyst (popliteal cyst):
    lump on the back of the knee, constant knee lump
    Urgency:
    Primary care doctor
  2. 2.Pimple

    Acne, also known as pimples, occurs when hair follicles become clogged with oil & dead skin cells. Acne is extremely common and ranges from mild to severe.

    The severity of the acne dictates treatment-type and duration. With proper treatment, acne should resolve in weeks to months. In some cases, acne is a long-term condition.

    Rarity:
    Common
    Top Symptoms:
    pink or red facial bump, small facial lump, painful facial bump, marble sized facial lump
    Symptoms that always occur with pimple:
    pink or red facial bump
    Urgency:
    Self-treatment
  3. 3.Boil (Furuncle)

    Boils are infections of a hair follicle that creates a small pocket of inflammation full of pus. It's typically caused by a common bacteria called S. Aureus.

    5-10 days

    Rarity:
    Uncommon
    Top Symptoms:
    pink or red facial bump, small facial lump, painful facial bump, marble sized facial lump, constant skin changes
    Symptoms that always occur with boil (furuncle):
    pink or red facial bump
    Symptoms that never occur with boil (furuncle):
    fever
    Urgency:
    Self-treatment

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  4. 4.Osteoid Osteoma

    An osteoid osteoma is a benign (non-cancerous) tumor that usually develops in the long bones of the legs. The thigh bone (femur) is affected most commonly, although the bones of the hand or the spine can have occasional involvement. This condition is most often found in young people.

    Good prognosis, 90% chance that the condition will not come back. A short recovery time after surgery is expected.

    Rarity:
    Rare
    Top Symptoms:
    lower back pain, upper back pain, spontaneous back pain, back pain that shoots to the butt, severe back pain
    Symptoms that never occur with osteoid osteoma:
    hip pain, bilateral leg swelling, weakness in both arms, weakness of both legs
    Urgency:
    Primary care doctor
  5. 5.Skin Abscess

    A skin abscess is an infection of the deeper skin that's typically due to bacteria seen on the skin. Recently, infections are more frequently caused by Staph. Aureus (puts the "staph" in "staph infections"), which is dangerous and requires treatment.

    Good prognosis with treatment

    Rarity:
    Common
    Top Symptoms:
    rash with bumps or blisters, red rash, red skin bump larger than 1/2 cm in diameter, pus-filled rash, rash
    Symptoms that always occur with skin abscess:
    rash with bumps or blisters
    Urgency:
    Primary care doctor
  6. 6.Fibrous Dysplasia of Bone

    This is a genetic condition where part of a bone develops incorrectly using the wrong type of materials (fibrous instead of bony tissue), causing a weak area of bone that is prone to fractures. This process begins before birth, and the cause of the gene mutation is not fully known.

    This is a lifelong condition, as the fibrous tissue will continue to grow in the same area.

    Rarity:
    Ultra rare
    Top Symptoms:
    spontaneous bone pain, groin pain, pain in one thigh, spontaneous hip pain, upper leg bump
    Symptoms that always occur with fibrous dysplasia of bone:
    spontaneous bone pain
    Urgency:
    Primary care doctor
  7. 7.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.

    Will remain for life if not treated with surgery, but is benign and is not expected to affect life expectancy.

    Rarity:
    Ultra rare
    Top Symptoms:
    lower leg bump, upper leg bump, numbness in one thigh, painful thigh lump, hip bump
    Urgency:
    Primary care doctor

Questions Your Doctor May Ask About Painful Knee Lump

  • Q.What color is the bump?
  • Q.Is your bump getting bigger?
  • Q.Any fever today or during the last week?
  • Q.Is there anything on the surface of the bump?

If you've answered yes to one or more of these questions, try our painful knee lump symptom checker to find out more.

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Painful Knee Lump Symptom Checker Statistics

  • People who have experienced painful knee lump have also experienced:

    • 12% Knee Pain
    • 8% Knee Stiffness
    • 6% Knee That Clicks During Movement
  • People who have experienced painful knee lump had symptoms persist for:

    • 39% Over a Month
    • 25% Less Than a Week
    • 15% Less Than a Day
  • People who have experienced painful knee lump were most often matched with:

    • 60% Baker's Cyst (Popliteal Cyst)
    • 20% Pimple
    • 20% Boil (Furuncle)
  • Source: Aggregated and anonymized results from visits to the Buoy AI health assistant (check it out by clicking on “Take Quiz”).

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