Finding a lump or nodule can be scary, but not all lumps are cancer. Many benign (non-cancerous) conditions can cause nodules that grow over time. While any new or growing lump should be evaluated by a doctor, they often turn out to be harmless. Understanding the differences between cancerous and benign growths can help put your mind at ease.
What is a nodule?
A nodule is simply a lump or mass that can form anywhere in the body. Doctors usually describe nodules based on their location:
- Thyroid nodule – lump in the thyroid gland in the neck
- Lung nodule – round lesion in the lungs
- Breast nodule – lump in the breast tissue
- Skin nodule – bump under the skin
- Kidney nodule – mass on the kidneys
Nodules can vary greatly in size, from microscopic to several centimeters big. They may be felt under the skin, detected incidentally on imaging tests, or found during a physical exam.
What causes nodules?
Both cancerous and non-cancerous conditions can lead to nodules. Here are some common causes:
Benign nodules
- Cysts: Fluid-filled sacs that can form in many parts of the body. Complex cysts have both fluid and solid components.
- Lipoma: Benign fatty tumor that can form under the skin anywhere on the body.
- Fibroadenoma: Non-cancerous breast mass made of gland and fibrous tissue.
- Granuloma: Nodule of inflamed tissue that can form as an immune response to infection or foreign material.
- Hamartoma: Benign overgrowth of normal cells or tissues.
- Adenoma: Benign tumor of glandular tissue such as the thyroid.
Cancerous nodules
- Carcinoma: Malignant tumor of epithelial tissue that can occur in many organs such as the lungs, breasts, thyroid, and liver.
- Sarcoma: Cancerous tumor arising from connective tissues like fat, muscle, nerves, bone, and cartilage.
- Lymphoma: Cancer starting in the lymphatic system, often presenting as lymph node enlargement.
- Metastasis: Spread of cancer from a primary tumor to other sites in the body.
Can a benign nodule grow over time?
Yes, many benign nodules increase in size gradually. Growth does not necessarily mean cancer. Here are some examples of commonly growing benign masses:
Sebaceous cyst
Sebaceous cysts, also called epidermoid cysts, are benign bumps that develop underneath the skin. They originate from the oil glands and often appear on the face, neck, torso, and back. Sebaceous cysts contain a cheese-like, fatty substance called keratin. They can range from a few millimeters to several centimeters in size. These cysts typically grow slowly over the course of weeks to months.
Lipoma
A lipoma is a benign tumor made of fat tissue. These soft, squishy lumps are usually located between the skin and underlying muscle layer. Lipomas commonly occur on the shoulders, neck, trunk, and back. They are typically small, between 1-3 cm, but can grow larger. Lipomas often develop gradually over months or years.
Uterine fibroids
Uterine fibroids are non-cancerous growths that develop from the muscular wall of the uterus. Also called leiomyomas or myomas, they are the most common pelvic tumor in women. Fibroids range greatly in size and can grow singly or in clusters. They typically enlarge slowly over months and years.
Ganglion cyst
Ganglion cysts are fluid-filled lumps that usually form near joints and tendons, most often in the hands and wrists. The fluid inside the cyst comes from the surrounding joint or tendon sheath. Ganglion cysts are benign and tend to grow progressively larger over time, ranging from 1-3 cm in size. However, they can resolve on their own or stop growing.
When should a nodule be evaluated?
Any new lump or mass warrants a visit to your healthcare provider. All nodules should be professionally evaluated, even if they are likely benign. Your doctor will consider your symptoms, medical history, and risk factors. They may recommend watchful waiting, additional testing, or biopsy to identify the type of nodule.
You should make an appointment to have a nodule checked if:
- You notice a new lump or bump anywhere on your body
- An existing mass has grown larger or changed
- The nodule is large, over 2 cm (about 1 inch)
- It causes pain, tenderness, swelling, or discomfort
- It feels firm or hard
- It does not move easily under the skin when prodded
- It persists for more than a month
Nodules that require prompt evaluation include:
- Breast lumps in women
- Neck masses
- Skin lumps that grow quickly or bleed
- Firm testicular lumps
- Lung nodules in smokers
Tests to evaluate a nodule
If a concerning nodule is found, your doctor has several tools to identify whether it is benign or malignant:
Imaging tests
Tests like ultrasound, CT, MRI, and PET scans provide detailed views of internal nodules and help characterize their appearance. In the breast, a mammogram can detect masses and microcalcifications suggestive of cancer.
Biopsy
Removing cells or a small sample of the lump for examination under a microscope is the most definitive way to diagnose a nodule. Fine needle aspiration, core needle biopsy, or surgical biopsy procedures may be used.
Blood tests
Lab tests to measure tumor marker levels can help diagnose certain cancers that produce abnormal proteins, like PSA for prostate cancer.
Endoscopy
Inserting a tiny camera inside the body allows direct visualization of growths in areas like the throat, stomach, colon, and bladder. Suspicious lesions can then be biopsied.
Can a cancerous nodule grow slowly?
Yes, even cancerous tumors do not always enlarge quickly. Some malignant nodules grow at slower rates and may persist for years before becoming symptomatic. Cancers such as thyroid, prostate, cervical, and early breast cancer can gradually increase in size over months. Any persistent nodule or lump should raise suspicion for malignancy.
Features that make a nodule more concerning for cancer include:
- Diameter over 2 cm
- Rapid enlargement
- Pain or discomfort
- Hard, fixed feel upon palpation
- Irregular shape with ill-defined borders
- Fixation to surrounding tissue
- Abnormal appearance on imaging
- Ulceration of the overlying skin
- Associated lymph node swelling
However, even small nodules less than 2 cm warrant evaluation, as cancer in its early stages can be difficult to distinguish from benign growths based on size alone.
Can cancer be ruled out without a biopsy?
In most cases, a biopsy is required to confirm or rule out cancer. While imaging and lab tests are helpful, they cannot provide a definitive diagnosis in many cases. There are some exceptions where the likelihood of cancer is so low that a doctor may not recommend biopsy:
- Simple cysts with typical benign features on ultrasound
- Small thyroid nodules in young patients that appear very low risk
- Some small incidental lung nodules that remain stable over years of imaging follow-up
However, when there is any uncertainty about the nature of a nodule, biopsy should be performed to obtain a pathological specimen proving benign disease.
Can cancer be cured if found early?
Detecting cancer at its earliest stages before it has spread significantly improves the chances for successful treatment and cure. Many malignant nodules represent localized disease caught early when it is most curable. For example:
- Stage 1 melanoma confined to the skin has a 5-year survival rate over 90%. But if melanoma spreads to distant organs, the 5-year survival falls to 23%.
- The 5-year survival for breast cancer is 99% when localized but just 27% once it has metastasized.
- Early prostate cancer confined to the prostate has nearly 100% 5-year survival, but after spreading this drops to 30%.
So a small malignant nodule found incidentally and removed surgically while still localized can often lead to excellent outcomes. Catching concerning nodules early before they enlarge and spread is critical to prognosis.
Takeaway Points
- Not every lump or nodule is cancerous – many benign conditions can cause nodules.
- Benign nodules such as lipomas, cysts, and fibroids often gradually enlarge over time.
- Cancerous nodules also frequently grow slowly, misleadingly acting like benign masses.
- The only way to definitively diagnose a suspicious nodule is through biopsy.
- Nodules detected early when still localized are often highly curable.
- Any new or growing mass warrants prompt medical evaluation.
The bottom line
While most nodules are non-cancerous, their presence should never be ignored. Any lump or mass that is new, growing, feels hard, or causes symptoms needs evaluation to determine the cause. Catching concerning nodules early when treatment is most effective allows the best chance for a cure. Speak to your doctor right away if you find a new or changing nodule on your body.