If you have noticed a lump on the top of your foot, it is important to investigate the possible underlying issues that may be causing it. Some quick self-assessment questions you might want to think about are:
- Is it painful?
- Is it soft or hard?
- Is it a different colour than the rest of the skin on your foot?
- Have you recently had an injury to the area?
Below are eight potential causes.
A bone spur, also known as an osteophyte, is a bony growth that forms on normal bone . It usually develops where bones meet or in places where there is constant pressure or friction.
Bone spurs can occur in any bone, but are most common in joints, particularly the spine, shoulders, hands, hips, knees and feet.
They can be asymptomatic or cause pain, swelling, or restricted movement, depending on their location and size.
Bursitis is a painful condition that occurs when small, fluid-filled sacs called bursae become inflamed . Bursae provide cushioning between bones, tendons and muscles and can be found throughout the body.
When a bursa becomes inflamed, it can cause:
- Restricted mobility
The symptoms typically persist for a few weeks and can be relieved by:
- Resting the affected area
- Using ice
- Taking nonsteroidal anti-inflammatory drugs (NSAIDs) available over-the-counter, such as aspirin or ibuprofen.
It's essential to schedule an appointment with your doctor if:
- Bursitis symptoms do not improve within two weeks
- The pain intensifies
- There is excessive inflammation in the impacted region
A cutaneous horn  is a rare condition where a growth that looks a bit like an animal horn made of keratin protein forms on the top layer of skin. They are usually found on the face, neck, shoulders, or feet.
If you have a cutaneous horn, you should make an appointment with your doctor if there is:
- inflammation around the area
- rapid growth
- the horn hardens at its base
A ganglion cyst is a noncancerous, fluid-filled lump or mass that usually develops along the tendons or joints of your wrists or hands, although they can also occur in your feet .
The cause of ganglion cysts is unknown, but they may be related to an injury or overuse of the affected area.
In most cases, ganglion cysts are harmless and don't require treatment, but they can cause discomfort or pain if they press on a nerve.
Some people who have them don't have any symptoms, but others may have:
- Tingling in the affected area
- Loss of mobility
Sometimes ganglion cysts go away without treatment, but sometimes people decide to have them removed. A doctor can remove the cyst with surgery or by draining the fluid with a needle.
Gout is a condition caused by a buildup of uric acid crystals . It results in swelling and inflammation in the foot, typically around the base of the big toe. The pain and burning sensation associated with gout can come on suddenly.
A doctor can diagnose gout through a blood test, an X-ray, or an ultrasound.
Medication is typically recommended as treatment. However, making lifestyle changes, such as adjusting your diet and quitting smoking can also help manage and improve symptoms.
Hallux rigidus  is a type of arthritis that appears at the base of the big toe due to damaged or lost cartilage.
This condition usually affects people between the ages of 30 and 60, and it can lead to pain and stiffness while walking and difficulty moving the big toe.
To manage Hallux rigidus, you can try different treatments, such as soaking your feet in warm and cold water and wearing shoes that prevent your big toe from bending.
If the condition progresses and becomes more severe, your doctor might suggest surgery as an option.
When a soft, movable lump is felt under the skin with your finger, it could be a sign of a lipoma .
Lipomas are non-cancerous growths made up of fatty tissue that can develop in various body parts, including the top of the foot.
To diagnose a lipoma, your doctor will usually conduct a physical examination or take a biopsy. Since lipomas are often benign, they may suggest a wait-and-see approach. However, surgical removal may be an option if the growth bothers you.
People with rheumatoid arthritis  may experience the formation of rheumatoid nodules, which are firm lumps under the skin that can range from the size of a pea to that of a walnut.
These nodules often appear in proximity to the joints affected by arthritis, and they are generally painless unless they press against a nerve or there is an underlying inflammation.
If rheumatoid nodules do not respond to rheumatoid arthritis medications like DMARDs, your doctor may might propose other treatments like a steroid injection or surgical removal.
There are various possible causes of a lump on top of the foot, including bone spurs, ganglion cysts, bursitis, gout, or sebaceous cysts.
Some of these conditions don't need to be treated, but others might require medication or surgical removal.
Having a lump on top of your foot can in rare cases be a sign of a more serious problem, so it’s worth getting it checked as soon as you notice one.