What Causes Hard Forearm Lumps & When to Seek Care

Malignant causes

In general, any growth is the result of cells dividing and growing uncontrollably. Sometimes there is a genetic mutation in DNA or a specific protein that results in this unchecked growth. These abnormal cells accumulate to form a noticeable lump. A lump (also known as a tumor) can be benign and can arise from many of the causes above. However, if this lump grows and invades the body, it is considered malignant. For example, a rare type of cancer called sarcoma originates in the supportive, connective tissues of the body and can result in a hard forearm lump before or as it spreads.

This list does not constitute medical advice and may not accurately represent what you have.

Skin abscess

A skin abscess is a large pocket of pus that has formed just beneath the skin. It is caused by bacteria getting under the skin, usually through a small cut or scratch, and beginning to multiply. The body fights the invasion with white blood cells, which kill some of the infected tissue but form pus within the cavity that remains.

Symptoms include a large, red, swollen, painful lump of pus anywhere on the body beneath the skin. There may be fever, chills, and body aches from the infection.

If not treated, there is the risk of an abscess enlarging, spreading, and causing serious illness.

Diagnosis is made through physical examination.

A small abscess may heal on its own, through the body's immune system. But some will need to be drained or lanced in a medical provider's office so that the pus can be cleaned out. Antibiotics are usually prescribed.

Keeping the skin clean, and using only clean clothes and towels, will help to make sure that the abscess does not recur.

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

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

Severe 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"). If the infection begins to spread, urgent treatment is required.

You should head to the nearest ER by car since your infection seems like it might be spreading. It is likely that you will be prescribed antibiotics. Surgery may be required to get rid of the whole abscess after the inflammation has died down. Do not drain the abscess yourself.

Rarity: Rare

Top Symptoms: fatigue, fever, painful neck lump, marble-size neck lump, pink or red neck bump

Symptoms that always occur with severe skin abscess: pink or red neck bump, red bump

Urgency: Hospital emergency room

Melanoma

Melanoma is the most serious type of skin cancer. Often the first sign of melanoma is a change in the size, shape, color, or feel of a mole. Most s have a black or black-blue area. Melanoma may also appear as a new mole. It may be black, abnormal, or "ugly looking."

You should visit your primary care physician. Surgery is the first treatment of all stages of melanoma. Other treatments include chemotherapy and radiation, biologic, and targeted therapies. Biologic therapy boosts your body's own ability to fight cancer. Targeted therapy uses substances that attack cancer cells without harming normal cells.

Rarity: Rare

Top Symptoms: brown-colored skin changes, atypical features of a facial bump, black-colored skin changes, growing facial lump, large facial lump

Symptoms that always occur with melanoma: atypical features of a facial bump

Urgency: Primary care doctor

Lipoma

Lipoma is a word that translates as "fatty tumor," but a lipoma is not cancer. It is simply a growth of fat between the muscle layer and the skin above it.

The exact cause is not known. The condition does run in families and is associated with other unusual syndromes such as adiposis dolorosa, which is similar. Lipomas most often appear after age 40.

Symptoms include a soft, easily moveable lump beneath the skin, about two inches across. A lipoma is painless unless its growth is irritating the nerves around it. They are most often found on the back, neck, and abdomen, and sometimes the arms and upper legs.

It is a good idea to have any new or unusual growth checked by a medical provider, just to make certain it is benign.

Diagnosis is made through physical examination, biopsy, and imaging such as ultrasound or CT scan.

Most of the time, treatment is not necessary unless the lipoma is unsightly or is interfering with other structures. It can be removed through surgery or liposuction.

Rarity: Uncommon

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

Symptoms that always occur with lipoma: skin-colored groin bump

Urgency: Wait and watch

Insect bite on the arm

Insect bites are very common. They often cause itchiness, redness, and some swelling. Most insect bites can be treated at home.

Rarity: Common

Top Symptoms: swollen forearm, mild forearm pain, forearm bump, forearm redness, forearm itch

Symptoms that never occur with insect bite on the arm: fever, worsening forearm redness, severe forearm pain, high-pitched breathing, wheezing, racing heart beat

Urgency: Self-treatment

Forearm wart

Warts, also called common warts or verrucae, are small, rough, rounded growths on the top layer of the skin. They may appear singly or in clusters.

Common warts are caused by the human papilloma virus (HPV) and are contagious through direct contact, especially through a break in the skin. They may spread from one place on the body to another simply through touch.

Anyone can get warts but they are most common in anyone with a weakened immune system, as from illness or chemotherapy. Children and teenagers are also susceptible to warts.

Warts often first appear on the hands and fingers, especially near the nails or after any injury to the skin. This is why biting fingernails is a risk factor for warts.

Warts are benign, meaning they are not cancerous. But they can be unsightly and interfere with normal use of the hands, so treatment is often beneficial.

Diagnosis is made through physical examination. Warts in children sometimes go away without treatment, but otherwise most warts can be easily removed in a doctor's office.

Rarity: Common

Top Symptoms: skin-colored forearm bump, painless forearm lump, small forearm lump, scaly forearm bump

Urgency: Self-treatment

Dermatofibroma

A dermatofibroma is a fairly common skin growth that usually appears on the lower legs, but may appear anywhere on the body. These mole-like growths are benign (noncancerous.)

The cause is not known, though a dermatofibroma may appear after a minor injury. The growths are not contagious.

Dermatofibromas are most common in adults and are rarely found in children.

Symptoms include a hard, raised growth that is red, pink, or brown and less than half an inch across. They are usually painless but may be tender or itchy, and may appear alone or in groups.

Any new growth on the skin should be seen by a medical provider, especially if the growth is very dark in color or changes its shape or appearance quickly.

Diagnosis is made through physical examination and sometimes biopsy.

A dermatofibroma does not require treatment unless it is interfering with clothing or is unsightly. They can be surgically removed, though this will leave a scar and the growth may eventually return.

Basal cell carcinoma

Basal cell carcinoma (BCC) is the most common kind of skin cancer. It can develop almost anywhere on the body. It appears as abnormal spots or bumps on the skin. These bumps are often pink, red, or skin-colored and sometimes have a shiny surface. The main risk factor for developing this condition is prolonged exposure to ultraviolet (UV) radiation. Sun exposure and tanning beds are both sources of UV radiation. People with a history of sunburns, previous skin cancer, and a weakened immune system are at higher risk for this condition.

Most cases of BCC can be easily treated because they grow slowly. Though if not treated, it can spread inside the body. Your provider will do a skin exam and possibly skin sample test, known as a biopsy. Treatment will depend on where the cancer is, its size, and your medical history. Some treatment options include cutting out the bump, freezing it, or using medicated skin cream.

Rarity: Uncommon

Top Symptoms: facial skin changes, pink or red facial bump, small facial lump, painless facial bump, growing facial lump

Urgency: Primary care doctor

Will the lump in my forearm go away on its own?

Depending on the cause, there is a possibility that the lump and the accompanying pain will go away on its own. If the forearm lump is a cyst or caused by environmental or inflammatory conditions, there is a good chance it will resolve on its own. However, if the forearm lump is a benign or malignant tumor, it will not resolve on its own and will require specific treatment.

Will the lump spread from one forearm to the other?

If the lump is red or multiple lumps appear on one arm, this is most likely an inflammatory etiology like panniculitis. These bumps may spread and affect the other arm or another limb in the first few weeks; however, they can be easily treated and often resolve on their own. Other causes of forearm lumps, on the other hand, usually do not spread from one forearm to the other.

Is the lump chronic or temporary?

A forearm lump may be temporary or chronic depending on the cause. A chronic forearm lump is more associated with benign or malignant growths, whereas temporary lumps are more associated with traumatic or inflammatory causes. However, arthritic nodules are a chronic, inflammatory etiology and need proper follow-up with a specialist, such as a rheumatologist.

How will the lump affect my daily activities?

A forearm lump can be very painful and uncomfortable, but those related to temporary etiologies should not affect you long-term. After a traumatic event, bed rest and limited activity with the affected forearm will help with recovery. A forearm lump associated with a benign or malignant growth may cause fatigue or unexplained weight loss, which may inhibit your energy to complete tasks. See your physician promptly if you feel like your symptoms are significantly affecting your life.

What can I do to prevent the development of forearm lumps?

It is very difficult to prevent the development of forearm lumps. The only situations in which the development of forearm lumps may be prevented are those related to environmental factors. There are several strategies you can employ to prevent bites from occurring, such as wearing protective clothing, using insect repellent, and going outside at times when mosquitoes are less active (during the day, after dawn, and before dusk).

Questions your doctor may ask about hard forearm lump

• What color is the bump?
• Is your forearm bump painful to the touch?
• Any fever today or during the last week?
• Do you have a rash?

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