Lumps & bump on the bottom of the foot can be a result of many underlying disorders like plantar fibromatosis, plantar warts, cysts, Haglund’s deformity & sarcoma.
Usually patient refer these bumps as nodules, cyst, knot, swelling, and lumps.
Whatever you name it, it is a swelling or a growth visible on the bottom of the foot which is resulted by an underlying pathological process within the bottom of the foot. 
Trauma, infection, hampered distribution of the weight-bearing force on foot can lead to inflammation which creates lumps on foot.
These bumps can be itchy, painful or painless, which depends upon their cause of origin. Often they cause discomfort & pain while walking.
Common causes for the bump & lump on the bottom of the foot include:
- Plantar fibromas
- Corn & Callous
- Plantar warts
- Athlete’s foot
- Foot blisters
- Inclusion cysts
Causes can be identified by locating the area of nodules on the bottom of the foot. Some of these require medical attention while some (like warts) may regress on their own over the period.
But seeking medical treatment helps to diagnose the underlying disease and reduce the discomfort and pain.
Also known as plantar fibromatosis or ledderhose disease.
It causes the formation of small nodule within the plantar fascia and usually, it appears on the middle part of the arch of the foot and affects one foot in most of the cases. While it is found that approximately 25% of cases have both feet affected.
These nodules are usually benign in type but always require treatment to get relief, because it does not fade away by its own. 
After clinical examination and proper imaging tests, the doctor will able to confirm this diagnosis.
Once the diagnosis is confirmed, treatment part involves minimizing pressure on foot by rest & using foot orthotics, steroid injections, and surgery.
Corn & Callous
Corn and calluses are the protective mechanism of our body to minimize the destruction caused by friction over the bottom of the foot.
Usually, they are caused by wearing the faulty foot gears, abnormal foot mechanics and high level of feet activities. 
Corn and calluses are two different things and should not be confused with one another.
Corns usually appear on the side of feet and is a small patch of thick, dead skin which has a central core. It can cause a hard bump on side of the foot.
Corns are well-delimited hyperkeratosis of tissues often seen in the athletes, while darkly pigmented skin, older age groups are more prone to develop the corns. Also, due to narrow footwear, the female tends to develop them more than males. 
Tender corn that forms at weight-bearing areas of the foot is known as seed corn. Plugged ducts of sweat gland can be a cause of seed corns.
Calluses that occur at plantar region commonly known as plantar calluses.
It is mainly caused by repetitive friction on the skin, which may be triggered by high-heeled shoes, ill-fitting shoes, abnormal walking motion, standing on feet for long hours, etc.
Usually, calluses are large than the corns and have diffused look with undefined boundaries. They often develop on weight-bearing parts of the body like a sole, ball of the heel, etc.
Corn & calluses can be avoided by using well-fitting shoes and avoiding things that lead to friction with foot skin.
Use Mole Skin Pads minimize friction and can help to prevent corns, calluses and blisters.
Soaking foot in warm water for a few minutes may help to soften the hard skin. Once it becomes soft to use the best callus remover to get rid of hard skin from corns & calluses.
Shop for the best skin moisturizing cream for feet on Amazon.
Warts can grow on any part of the body including the lower part of the foot and it can be the cause of small bumps on the bottom of feet.
As they grow on the plantar area, commonly known as plantar warts or verrucae plantaris. Warts are caused by HPV i.e. human papilloma-virus.
Most of the time these warts are not painful, benign lesions but as they grow, walking and standing on foot becomes difficult. 
Multiple warts may grow together forming a cluster and this condition is called mosaic warts.
Usually, these kinds of warts fade away on its own but if they fail to go away then some active treatment is recommended.
Using duct tape is one of the useful home remedies for removing plantar warts. Apply it on the wart and keep it there for approximately 5 to 6 days then remove the tape and soak the foot in warm water & remove a soft part.
You might need to repeat this procedure 2 to 3 times depending on the size of a wart. 
An over-the-counter Salicyclic acid-based ointment can provide results in some cases while in some cases it fails to deliver desired results.
Other treatment options include freezing the wart with nitrogen oxide, removing it with surgery or laser, etc.
Modern medicine has very few useful options to cure warts while the Homoeopathic system of medicine has shown some promising results in warts & other skin disorders.
Fungal infection between toes is known as Athlete’s foot and as the name suggest it is more common in athletes.
Fungal infection is mostly triggered by sweaty feet and tight-fitting shoes. It is commonly known as tinea pedis.
It shows typical symptoms of fungal infection like itching, blisters between toes & scaly skin. 
Athlete’s foot is one of the common cause for the itchy bumps on the bottom of the feet.
Infection of fungus can spread person-to-person by sharing the same towels or clothing. Keeping feet wet, visiting public places barefoot, sharing footwear or socks with others may spread the fungal infection.
Doctor diagnose the athlete’s foot by examining the lesions and considering other symptoms. But if the doctor is unsure about the diagnosis he might ask you to carry a skin lesion KOH exam which is common test to diagnose the fungus infection of the skin. [07.1]
Treatment involves using dry and clean socks, applying anti-fungal ointment and pills and paying attention to personal hygiene.
This is another reason that creates the bump on foot.
Blisters are small, fluid packed sacks that look like a bubble on the surface of the skin.
It is caused by ill-fitting shoes that rub against the skin and causes blisters. Sometimes it may get the secondary infection. 
It is advisable not to pop these blisters as they may get infected. Instead, opt for well-fitting shoes and cover the blisters with tape.
Check out slide share that will help you to prevent foot blisters in future –
A cyst that includes foreign body is known as inclusion cyst. Cyst on bottom foot can be an inclusion cyst.
These foreign bodies can be a small piece of wood, glass or tiny part of the metal. It can be anything. The body is usually unable to expel it out and build the wall around it to protect surrounding tissues.
Usually, people steps on a sharp object and these object break off in small pieces within foot tissues and get trapped inside foot tissues.
Surgical removal is the most recommended line of treatment for such cyst.
Porokeratosis is a dermatological condition, where the patient suffers from a group of different skin problems.
Porokeratosis on foot and palm usually characterized by the small seed-like hyperkeratotic lesions. These lesions come in the group and have raised margins that look like a ridge.
They grow on the weight-bearing part of the foot, so commonly found in the heel area and sometimes can also be found of an arch of the foot.
Some patients feel pain while some don’t. So the discomfort caused by the porokeratosis varies from person to person.
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