Tumors and Growths: Types, Causes & Treatment

A tumor is a lump or mass that forms when cells multiply abnormally. While the word "tumor" often causes concern, the vast majority of tumors and growths discovered on or in the body are benign (non-cancerous). Understanding the difference between benign and malignant growths, recognizing common types, and knowing when to seek medical evaluation can help reduce anxiety and ensure timely care when needed.

What Is a Tumor and How Does It Form?

A tumor is a mass of tissue that forms when cells in the body begin to grow and divide abnormally. The word "tumor" simply means "swelling" or "lump" in Latin, and most tumors are benign (non-cancerous). Tumors can develop in virtually any part of the body, from visible locations on the skin to internal organs.

Under normal circumstances, the human body carefully controls cell growth and division through a complex system of molecular signals. Cells grow, divide, and die in an orderly fashion. When this regulation fails, cells may continue to multiply even when new cells are not needed, leading to the formation of a mass or lump—what we call a tumor or neoplasm.

The development of a tumor typically begins with genetic changes in a single cell. These changes can be inherited, caused by environmental factors (such as UV radiation, chemicals, or certain viruses), or occur randomly during cell division. When enough genetic changes accumulate, the cell loses its normal growth controls and begins dividing excessively. Over time, these abnormal cells can form a detectable mass.

It is important to understand that tumors exist on a spectrum. Some are entirely harmless and may never require any treatment. Others may need removal because they cause symptoms or have a small potential to become cancerous. And some are malignant from the start, requiring prompt medical intervention. The key distinction lies in the biological behavior of the tumor cells.

Benign Tumors (Non-cancerous)

Benign tumors are non-cancerous growths that do not invade surrounding tissues or spread to other parts of the body. They typically grow slowly and have well-defined boundaries, making them distinct from the normal tissue around them. In many cases, benign tumors remain stable in size for years or even decades.

The cells in benign tumors closely resemble normal cells of the tissue where they originated. They maintain their differentiation—meaning they retain the specialized features and functions of their tissue type. This is in contrast to cancer cells, which often lose their differentiated characteristics.

Most benign tumors do not require treatment unless they cause symptoms. However, treatment may be recommended if a benign tumor presses on nerves, blood vessels, or organs; causes pain or discomfort; affects appearance; becomes infected; or has potential for malignant transformation.

Malignant Tumors (Cancerous)

Malignant tumors are cancerous growths that can invade nearby tissues and spread (metastasize) to distant parts of the body through the blood or lymphatic system. Unlike benign tumors, cancer cells do not respect normal tissue boundaries. They can grow into and destroy surrounding structures.

Cancer cells typically show abnormal features when examined under a microscope. They may have unusual shapes, enlarged nuclei, and a high rate of division. The process by which normal cells transform into cancer cells involves multiple genetic mutations that accumulate over time, disabling the normal cellular controls on growth and survival.

Malignant tumors generally require treatment, which may include surgery, radiation therapy, chemotherapy, immunotherapy, targeted therapy, or combinations of these approaches. The specific treatment depends on the type of cancer, its stage (how far it has spread), the patient's overall health, and other factors.

What Are the Most Common Types of Benign Tumors?

The most common benign tumors include lipomas (fatty lumps), cysts (fluid-filled sacs), fibromas (fibrous tissue growths), moles, sebaceous cysts, hemangiomas (blood vessel tumors), and polyps. Most of these are harmless and require no treatment unless they cause symptoms or cosmetic concerns.

Benign tumors are classified based on the tissue type from which they originate. Understanding the different types can help demystify these common growths and provide reassurance that most lumps people discover are entirely harmless. Below are detailed descriptions of the most frequently encountered benign tumors and growths.

Lipoma (Fatty Lump)

A lipoma is one of the most common benign tumors, consisting of mature fat cells enclosed in a thin fibrous capsule. Lipomas typically appear as soft, moveable lumps just beneath the skin. They are most often found on the trunk, neck, upper arms, and thighs, though they can occur almost anywhere on the body.

Lipomas usually grow slowly over months or years and rarely cause pain unless they press on a nerve. They are more common in people between 40 and 60 years old and may run in families. A single lipoma is harmless and rarely requires treatment unless it becomes bothersome, grows large, or causes discomfort. Multiple lipomas (a condition called lipomatosis) can occur in some individuals.

Cyst (Fluid-Filled Sac)

A cyst is a closed sac containing fluid, semi-solid material, or air. Cysts can form in many different tissues throughout the body, including the skin, ovaries, breasts, kidneys, and liver. The contents and behavior of cysts vary depending on their location and type.

Common types include epidermal (sebaceous) cysts in the skin, ovarian cysts in the reproductive system, and Baker's cysts behind the knee. Most cysts are benign and may not require treatment unless they become large, painful, infected, or interfere with organ function. Cysts are often monitored with imaging studies to track any changes over time.

Fibroadenoma (Breast Lump)

Fibroadenomas are the most common benign breast tumors, particularly in women under 30. These solid, round, rubbery lumps consist of both glandular and fibrous tissue. They are typically painless and move easily within the breast tissue when touched.

Fibroadenomas can range in size from too small to feel to several centimeters in diameter. While most fibroadenomas remain stable or even shrink over time (especially after menopause), some may grow larger. Simple fibroadenomas are not associated with an increased risk of breast cancer. Complex fibroadenomas, which contain additional features like cysts or calcifications, may carry a slightly elevated risk and are typically removed or monitored more closely.

Fibroma (Fibrous Tissue Growth)

A fibroma is a benign tumor composed of fibrous or connective tissue. These growths can occur anywhere in the body, including the skin, tendons, and internal organs. Skin fibromas often appear as small, firm nodules that may be the same color as the surrounding skin or slightly darker.

Soft fibromas, also called skin tags (acrochordons), are common harmless growths that appear as small, soft, flesh-colored protrusions, often on the neck, armpits, or groin. Hard fibromas (dermatofibromas) are firm, slightly raised nodules often found on the legs. Neither type typically requires treatment unless they become irritated or cosmetically bothersome.

Moles and Birthmarks (Pigmented Lesions)

Moles (nevi) are extremely common pigmented growths that can appear anywhere on the body. Most people have between 10 and 40 moles, which typically develop during childhood and adolescence. Moles are clusters of pigmented cells (melanocytes) that usually appear as small, dark spots.

The vast majority of moles are benign and remain stable throughout life. However, certain moles—particularly atypical (dysplastic) moles with irregular borders, multiple colors, or large size—have a slightly increased risk of developing into melanoma, a type of skin cancer. Regular self-examination and dermatological screening are important for early detection of any concerning changes.

Hemangioma (Blood Vessel Tumor)

A hemangioma is a benign tumor composed of blood vessels. The most common type, infantile hemangioma (commonly called a strawberry mark), appears in about 5% of infants and is more common in girls and premature babies. These typically appear as bright red, raised lesions on the skin.

Most infantile hemangiomas follow a predictable pattern: they grow during the first year of life, stabilize, and then gradually shrink over several years. By age 5-10, most have resolved significantly. Treatment is usually unnecessary unless the hemangioma interferes with vision, breathing, feeding, or causes other complications.

Adenoma (Glandular Tumor)

An adenoma is a benign tumor arising from glandular tissue. Adenomas can occur in various organs, including the thyroid, adrenal glands, pituitary gland, colon, and liver. The behavior and clinical significance of adenomas varies depending on their location.

Some adenomas produce excess hormones, leading to symptoms related to hormonal imbalance. For example, pituitary adenomas may cause various hormonal syndromes depending on which hormones they produce. Colonic adenomas (polyps) are particularly important because certain types can progress to colorectal cancer over time, which is why they are typically removed during colonoscopy.

Polyps (Mucosal Growths)

A polyp is a growth that protrudes from a mucous membrane. Polyps can develop in the nose, sinuses, stomach, colon, uterus, and other locations lined by mucous membranes. They may appear as rounded masses attached to the lining by a stalk (pedunculated) or by a broad base (sessile).

The clinical significance of polyps varies by location and type. Nasal polyps are usually related to inflammation and are benign. Colorectal polyps receive significant attention because certain types (adenomatous polyps) can develop into cancer over many years. This is why screening colonoscopy is recommended for adults to detect and remove potentially precancerous polyps.

What Other Common Growths Can Develop on the Body?

Beyond tumors, the body can develop various other growths including sebaceous cysts (blocked oil glands), ganglion cysts (joint fluid collections), warts (viral skin growths), skin tags, corns and calluses, and prostate enlargement. Most of these are benign and manageable with simple treatments.

In addition to the classic benign tumors described above, many other types of growths and lumps can develop throughout life. Understanding these common conditions can help reduce anxiety when you notice something new on your body. Most of these conditions are harmless, though some may require treatment for comfort or cosmetic reasons.

Sebaceous Cyst (Epidermoid Cyst)

A sebaceous cyst forms when a sebaceous gland (oil-producing gland in the skin) becomes blocked. These round, firm lumps are found just under the skin, most commonly on the face, neck, trunk, and scalp. They often have a small dark opening (punctum) visible on the surface.

Sebaceous cysts are generally painless unless they become infected, in which case they may become red, tender, and swollen. While they are completely benign, many people choose to have them removed for cosmetic reasons or if they become repeatedly infected. Complete surgical excision, including the cyst wall, prevents recurrence.

Ganglion Cyst

A ganglion is a fluid-filled cyst that typically develops near joints or tendons, most commonly on the wrist. These round or oval lumps contain thick, jelly-like synovial fluid. Ganglions are also called "Bible cysts" from the old practice of striking them with a heavy book to rupture them (not recommended today).

Ganglions are harmless but may cause discomfort if they press on nearby nerves. Many ganglions disappear spontaneously without treatment. For persistent or symptomatic ganglions, treatment options include immobilization, aspiration (draining the fluid), or surgical removal. Recurrence after aspiration is common.

Benign Prostatic Hyperplasia (Enlarged Prostate)

Benign prostatic hyperplasia (BPH) is a non-cancerous enlargement of the prostate gland that is extremely common in men over 50. As the prostate enlarges, it can compress the urethra and cause urinary symptoms such as frequent urination, difficulty starting urination, weak stream, and incomplete bladder emptying.

BPH is not related to prostate cancer, though both conditions become more common with age and can cause similar symptoms. Treatment depends on symptom severity and may include lifestyle modifications, medications to relax prostate muscle or shrink the gland, or surgical procedures to remove or reduce prostate tissue.

Warts (Viral Growths)

Warts are skin growths caused by infection with human papillomavirus (HPV). Common warts typically appear on the hands as rough, raised bumps, while plantar warts develop on the soles of the feet. Flat warts, which are smoother and smaller, often occur on the face and legs.

Warts are contagious but generally harmless. They often resolve spontaneously as the immune system clears the viral infection, though this can take months or years. Treatment options include over-the-counter salicylic acid preparations, cryotherapy (freezing), laser treatment, and other procedures for persistent warts.

Seborrheic Keratosis

Seborrheic keratoses are extremely common benign growths that appear as waxy, scaly, slightly raised patches. They range in color from light tan to brown or black and often look like they are "stuck on" the skin. They are most common on the face, chest, shoulders, and back.

These growths are more common with age and sometimes called "wisdom spots" or "barnacles." They have no malignant potential and require no treatment unless they become irritated or are cosmetically bothersome. If there is any doubt about the diagnosis, a biopsy may be performed to rule out melanoma or other skin cancers.

Corns and Calluses

Corns and calluses are thickened areas of skin that develop in response to repeated friction or pressure, most commonly on the feet and hands. Calluses are flat, broad areas of thickened skin, while corns are smaller, more focused areas with a hard center.

These protective responses of the skin are not tumors but can become painful if allowed to build up excessively. Treatment involves removing the source of friction (such as ill-fitting shoes), regular filing or pumicing of thickened skin, and protective padding. People with diabetes or poor circulation should seek professional care for corns and calluses.

How Can You Tell If a Tumor Is Benign or Cancerous?

You cannot determine whether a lump is cancerous by looking at or feeling it yourself. Proper diagnosis requires medical examination and typically involves imaging studies (ultrasound, MRI, CT scan) and often a biopsy, where tissue is examined under a microscope by a pathologist. If you discover a new lump or notice changes in an existing growth, consult a healthcare provider for evaluation.

One of the most important points to understand about tumors and growths is that self-diagnosis is not reliable or safe. While some characteristics may raise or lower suspicion for malignancy, only proper medical evaluation can determine the nature of a lump with certainty. Here we explain the diagnostic process and what characteristics physicians consider.

Clinical Examination

The diagnostic process typically begins with a thorough clinical examination. Your healthcare provider will ask about when you first noticed the lump, how it has changed over time, any associated symptoms (pain, bleeding, discharge), and relevant medical history including family history of cancer.

During the physical examination, the doctor will assess the characteristics of the growth including its size, shape, consistency (hard or soft), mobility (fixed or moveable), borders (smooth or irregular), and relationship to surrounding structures. They will also examine nearby lymph nodes and perform a general physical examination as appropriate.

Imaging Studies

Imaging studies help visualize the internal characteristics of a growth and its relationship to surrounding structures. Common imaging modalities include ultrasound, which is often the first-line investigation for superficial lumps; computed tomography (CT) scans for detailed internal imaging; magnetic resonance imaging (MRI) for soft tissue detail; and X-rays for bone involvement.

Imaging can provide valuable information about whether a growth appears solid or cystic, its internal structure, blood supply, and involvement of adjacent tissues. While imaging cannot definitively distinguish between benign and malignant tumors in all cases, certain features can raise or lower suspicion and guide the need for biopsy.

Biopsy and Pathology

The definitive diagnosis of most tumors requires microscopic examination of tissue by a pathologist. A biopsy involves removing a sample of the growth (or the entire growth in some cases) for laboratory analysis. Different biopsy techniques include fine needle aspiration (FNA), core needle biopsy, incisional biopsy (partial removal), and excisional biopsy (complete removal).

The pathologist examines the tissue under a microscope, assessing cell appearance, growth patterns, and other features that distinguish benign from malignant tumors. Additional tests such as immunohistochemistry (detecting specific proteins) and molecular testing may be performed to further characterize the tumor and guide treatment decisions.

When Should You See a Doctor About a Lump or Growth?

Consult a healthcare provider if you discover a new lump or growth, if an existing growth changes in any way, if a growth causes pain or other symptoms, or if you have risk factors for cancer. While most lumps are benign, professional evaluation provides accurate diagnosis and peace of mind.

Deciding when to seek medical attention for a lump can be challenging. Many people delay evaluation out of fear or assumption that the lump is harmless. Others may worry excessively about growths that are clearly benign. Understanding the guidelines for when to seek care can help you make informed decisions about your health.

Situations That Warrant Evaluation

There are several scenarios in which you should consult a healthcare provider about a lump or growth. A new lump that persists for more than two to three weeks deserves evaluation, even if it seems harmless. Any lump that is growing, particularly if the growth is rapid, should be examined promptly.

Changes in existing growths are important warning signs. This includes changes in size, shape, color, texture, or any new symptoms such as pain, bleeding, or discharge. Moles that change in any of these ways warrant particular attention due to the possibility of melanoma.

Lumps that are hard, fixed (immobile), or irregular in shape are more concerning than soft, moveable lumps with smooth borders. However, this is not a reliable way to self-diagnose, as some benign tumors can be firm and some cancers can feel soft.

Risk Factors That Lower the Threshold for Evaluation

Certain factors increase the risk of malignancy and should lower your threshold for seeking medical evaluation. These include personal history of cancer, family history of cancer (especially in first-degree relatives), previous radiation exposure, known genetic predispositions (such as BRCA mutations), immunosuppression, and history of precancerous conditions.

Age is also a consideration, as the risk of cancer increases with age. While benign tumors are common at all ages, a new lump in an older adult may warrant more thorough investigation than a similar lump in a young person.

What to Expect at the Medical Appointment

When you see a healthcare provider about a lump, they will take a detailed history and perform a physical examination. Be prepared to answer questions about when you first noticed the lump, whether it has changed, any associated symptoms, and your personal and family medical history.

Based on the clinical assessment, your provider may reassure you that the lump appears benign and recommend monitoring, or they may order further investigations such as imaging studies or a biopsy. The approach depends on the characteristics of the lump, your risk factors, and other clinical considerations.

How Are Benign Tumors Treated?

Many benign tumors require no treatment and can be safely monitored. Treatment is considered when a tumor causes symptoms, affects appearance, has potential for malignancy, or when there is diagnostic uncertainty. Treatment options include watchful waiting, surgical excision, and various minimally invasive procedures depending on the tumor type and location.

The management of benign tumors depends on several factors including the type of tumor, its location, size, symptoms, and the patient's preferences. Unlike cancer, which typically requires prompt treatment, many benign tumors can be observed without intervention. Understanding the treatment options can help you have informed discussions with your healthcare provider.

Watchful Waiting (Observation)

For many benign tumors, the recommended approach is watchful waiting or active surveillance. This means monitoring the tumor over time with regular clinical examinations and possibly periodic imaging studies, without any active treatment. This approach is appropriate when the tumor is not causing symptoms, is in a location where it poses no functional threat, and has no significant risk of becoming cancerous.

During watchful waiting, you and your healthcare provider will monitor for any changes that might indicate the need for intervention. Many benign tumors remain stable for years or even shrink over time, making intervention unnecessary. The key is regular follow-up to ensure any concerning changes are detected early.

Surgical Excision

Surgical removal is the definitive treatment for benign tumors when treatment is indicated. The goal is to remove the entire tumor with a margin of normal tissue to prevent recurrence. For superficial tumors like lipomas, cysts, and skin lesions, this can often be performed under local anesthesia as an outpatient procedure.

For tumors in more complex locations, more extensive surgery may be required. The surgical approach depends on the tumor's location, size, and relationship to surrounding structures. Modern surgical techniques, including minimally invasive and laparoscopic approaches, have reduced recovery times and complications for many procedures.

Other Treatment Modalities

Depending on the type and location of the tumor, various other treatments may be appropriate. Cyst aspiration involves draining fluid from a cyst with a needle, though cysts often recur after aspiration alone. Sclerotherapy involves injecting a solution that causes a cyst or abnormal blood vessel to shrink.

Cryotherapy (freezing) can be used for certain skin lesions like warts and seborrheic keratoses. Laser treatment is effective for some types of vascular lesions and skin growths. Medications may be helpful in certain situations, such as hormonal therapy for uterine fibroids or beta-blockers for problematic infantile hemangiomas.

When Treatment Is Recommended

While many benign tumors can be safely observed, treatment is generally recommended in several circumstances. If the tumor causes pain, discomfort, or functional impairment, removal typically provides relief. Tumors that are cosmetically bothersome may be removed at the patient's request.

Treatment is also recommended for tumors with malignant potential (like adenomatous polyps), when the diagnosis is uncertain and biopsy is needed, when a tumor is growing significantly, or when there is evidence of infection or other complications. The decision to treat is made collaboratively between you and your healthcare provider based on the specific circumstances.

Can Benign Tumors Become Cancerous?

Most benign tumors remain benign throughout life and never become cancerous. However, some specific types have a small potential for malignant transformation. Colorectal adenomatous polyps, certain ovarian tumors, and some types of moles are examples of benign lesions that can occasionally progress to cancer. Regular monitoring and preventive removal of high-risk lesions can significantly reduce cancer risk.

The question of whether benign tumors can become cancerous is one that concerns many people. The reassuring answer is that the vast majority of benign tumors remain benign and pose no cancer risk. However, understanding the exceptions is important for appropriate monitoring and prevention.

The Biology of Malignant Transformation

Malignant transformation is the process by which normal or benign cells acquire the characteristics of cancer cells. This occurs through the accumulation of genetic mutations that disable normal growth controls and enable cells to invade tissues and spread. While any cell theoretically has the potential for malignant transformation, the actual risk varies dramatically depending on the cell type and other factors.

Most benign tumors have limited proliferative capacity and stable genetics, meaning they have very low risk of accumulating the mutations needed for malignancy. The cells in these tumors are well-differentiated and maintain normal cellular controls, just with slightly increased growth rates or survival.

Benign Lesions with Malignant Potential

Certain benign lesions are recognized to have meaningful potential for progression to cancer and warrant special attention. Colorectal adenomatous polyps are the classic example. While these polyps are benign, they can progress through a well-characterized sequence (adenoma-carcinoma sequence) to become colorectal cancer over approximately 10-15 years. This is why screening colonoscopy with polyp removal is an effective cancer prevention strategy.

Dysplastic (atypical) moles have a slightly increased risk of melanoma compared to common moles. While most dysplastic moles never become cancerous, people with many dysplastic moles or a family history of melanoma warrant closer monitoring. Other examples include certain ovarian cysts (borderline tumors), some types of breast lesions, and specific thyroid nodules.

Monitoring and Prevention

For benign lesions with known malignant potential, regular monitoring and sometimes preventive removal are recommended. The specific approach depends on the type of lesion, individual risk factors, and clinical guidelines. For colorectal polyps, removal during colonoscopy is standard practice. For atypical moles, regular dermatological examination and prompt removal of suspicious lesions is advised.

It is important to maintain perspective: even among lesions with malignant potential, the majority never become cancerous. The purpose of monitoring and prevention is to catch the small percentage that do progress at an early, curable stage. For the typical benign tumor like a lipoma, cyst, or simple fibroadenoma, the risk of cancer is essentially zero.