Lump On Forearm

If you have lumps on the forearm, you may be concerned. However, most lumps are benign. Nevertheless, it's important to get it looked at by a doctor to ensure it doesn't indicate a bigger health problem.

Lumps on the Forearm

This is a discussion of lumps on the forearm, causes if known, and possible treatments. The possible lumps which appear on the forearm are called cysts, lipomas, fibromas, lumps, tumors, and nodules.

Regardless of cause or name, most lumps found on the forearm are benign, but should not necessarily be ignored. A doctor should be consulted if a strange, abnormal lump or growth appears under the skin.


Cysts are a common skin condition appearing as a smooth lump under the skin on the forearm. They are usually white, a yellowish color or skin colored. Cysts are a closed sac filled with fluid, pus, and other gelatinous material.

They are typically caused by:

  • Infection, inflammation from a scratch, acne, other trauma
  • Deformed duct
  • Blocked pores
  • Injuries, breaks in a blood vessel
  • Defective skin cells
  • Parasites
  • Tumors
  • Cancer

Types of Cysts

Epidermoid cysts develop when skin cells on the forearm move down beneath the skin surface then produce and form a wall, or capsule. The cells secrete keratin and sebum shaping the sac formed by the capsule.

The epidermoid cyst has the texture of a soft grape, can start out as the size of a pea but can grow to the size of a walnut. It won’t go away on its own but is painless unless it becomes infected, inflamed or ruptured.

With ensuing pain, a doctor should be consulted.

Sebaceous cysts develop inside the glands that secrete sebum. The sebum gets trapped under the skin forming a plug made up of oil, dirt, sweat, debris, and bacteria. Since oil can’t exit, a sac grows in the hair follicle.

A sebaceous cyst that becomes inflamed and swollen is difficult to remove; therefore, the cyst should be removed when the inflammation subsides.

A rupture of the cyst causes an abscess or boil-like sore and requires immediate medical treatment since it will automatically get infected.

Ganglion cysts develop at the wrist due to an injury. For instance, a fall or sports injury. Benign, the ganglion is actually multiple layers of fibrous tissue that form around the injury.

Live cells in the tissue build a sac that fills with synovial fluid. Synovial fluid is the substance that lubricates all joints in the body.

Ganglion cysts will spread and grow tentacle type roots that keep the cyst anchored to the joint. Doctor evaluation and treatment is required.

Other Types of Lumps on the Forearm


Lipoma lumps are an inherited condition. They are more malleable than a cyst and can easily be rolled around under the skin.

It appears as a squishy, fatty mass less than two inches in diameter. Lipoma doesn’t penetrate the surrounding tissue; however, it can press against a nerve(s) requiring it to be removed.

Removal is done by:

  • Surgery, or a manual extraction executed through a cut made at the site.

  • Liposuction for eliminating large lipomas.

  • Steroid shots.

Remember, fast growth and pain are red flags for cancer.


A fibroma tumor that is embedded in the second layer of the skin, the derma. While benign, it is a hard lump that feels like a stone.

The cause is not known, however, insect bites and jabs to the skin are suspect. With the bite or jab a solid substance of blood vessels, nerves and scar tissue form at the site.

It can be tender or itchy and is a pink to brown nodule, about half an inch in diameter. If pinched it dimples inward.

As a slow-growing condition, it will not go away on its own. If it is irritated by clothing, unsightly, suspicious looking or develops bleeding sores it should be removed.

It grows deep under the skin requiring a deep excision. A second option uses a scalpel to shave off top layers of the growth. This process flattens the nodule to skin level but leaves a chance of recurrence.


A fibroma tumor that affects the nervous system. It is a genetic condition whereby a lump forms on a nerve as a result of mutated genes.

Causing an overgrowth of nerve tissue, it is a slow-growing fleshy mass, emitting a shock-like feel when touched. If neurological symptoms exist then a nerve is trapped between a bone and the tumor.

The trapped nerve swells, becomes painful, and the entire mass must be surgically removed.

Keratosis Pilaris (KP)

KP is excessive production of keratin that falls into the hair follicle and causes lumps under the skin.

Treatment with keratolytic products, retinol, and moisturizers are helpful. Stronger prescribed medications and treatments are employed in severe cases.

Keratoacanthoma (KA)

KA is a slow-growing tumor and is benign regardless of its parallels to squamous cell carcinoma. It generally develops on skin exposed to the sun, and seldom spreads.

It forms at trauma or injury sites where cells multiply in the follicle. This debris forms keratoacanthomas in a crater or dome shaped lump.

A biopsy is needed to confirm the condition, followed by treatment. Treatment includes electrodesiccation with curettage, nitrogen freeze, an excision or a MOHS micrographic procedure and radiation.


Hives are swollen, itchy welt-like lumps spread across the skin. They are caused by allergies, sickness, sun, infection, and exercise. Hives develop in various sizes and as they fade new ones appear.

Treatment includes avoiding the causes of allergies, the use of antihistamines and prescribed steroids.


Moles appear as slightly raised, sometimes flat spots. Most do not present problems, and they are usually black or brown, not harmful and not contagious.

However, there are some cancerous red flags. Consult a doctor with:

1. Changes in color, shape, size
2. Continued growth outward in uneven edges
3. Grows up from the skin layer
4. Bleeds, hurts, changes texture


A hematoma is a localized condition that pools blood in the tissue under the skin. Pooling can be caused by anything from an insect bite, disease or injuries.

A bruise-like condition whereby blood spreads and coagulates. Pooled blood is eventually absorbed back into the blood vessels. If it doesn’t heal then blood is leaking out of broken capillaries. A doctor should be consulted.

Soft Tissue Sarcoma (STS)

STS appears as a swelling or painless lump under the forearm skin. Starting out anywhere healthy cells expand out of control it can be benign or cancerous.

Cancerous, or malignant, tumors spread throughout the body. If benign it grows but doesn’t spread.

Treatment is surgical removal with follow-up treatment.