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04 May 2022

Benign vs. malignant tumors: differences, symptoms, & classifications

symptoms 4 minutes reading time

What does it mean to have a malignant tumor?

Tumors–also known as neoplasms–are abnormal collections of cells that form because cells don’t die when they should, or multiply when they shouldn’t.1

Benign tumors are noncancerous and do not spread to distant parts of the body. They may or may not cause symptoms.

Malignant tumors are cancerous and often become locally invasive, infecting nearby tissue, or metastasize, spreading to different organs and body systems. They require medical interventions such as surgical removal, radiation, chemotherapy, and systemic therapy, and can be life-threatening if left undetected or untreated.

Key differences between benign and malignant tumors

Borders. The borders of a benign tumor are smooth, regular, and distinct. There is a clear shape to them, and you can tell where they begin and end. By contrast, malignant tumors have fuzzy, spiky, or otherwise irregular borders, and may lack distinct shape. Diagnostic medical imaging tools like ultrasound, MRI, and mammograms are able to capture highly detailed pictures of a tumor’s borders, especially when contrast dye is used.

Growth and spread. Benign tumors can grow in size, but they won’t spread (metastasize) to other parts of your body or invade adjacent tissue. Benign tumors that grow too large become problematic when they start encroaching on neighboring internal structures or causing troubling symptoms.  Malignant tumors are invasive, grow quickly in comparison to benign tumors, and often spread beyond their original location to other parts of the body.

Symptoms of malignant tumors

Tumor symptoms can vary by type, severity, location, etc. Some symptoms may indicate your body is fighting a malignancy (though any of these can have other explanations), such as:2

  • Deep fatigue that doesn’t improve with rest.
  • Fever, chills, or night sweats.
  • Unexplained weight loss or gain in excess of 10 pounds.
  • Nausea, vomiting, abdominal pain, or lack of appetite.
  • Bruising or bleeding easily.
  • Changes in bowel patterns and appearances.
  • Changes in urinary patterns and appearances.
  • Uncontrolled or inexplicable pain that doesn’t improve.
  • Sudden vision or hearing problems.
  • Dry cough that doesn’t go away.
  • Swelling, thickening, or lump(s) on any part of the body.
  • Skin changes, particularly new moles or sores that weep/will not heal.

Types of tumors

Tumors vary by location, size, type, cell behavior, and many other factors. Some brain tumors are benign; others are malignant. There are hundreds of known tumor types, so these lists are by no means exhaustive. However, they do cover many common examples of tumors that are regularly diagnosed with medical imaging scans.

Benign tumors:

  • Lipomas are the most common type of benign tumor. They’re fatty cysts that grow just under the surface of your skin.
  • Fibroid tumors can grow in the uterus (uterine fibroids). Though not cancerous, they can become painful when large and can interfere with menstrual cycles and health.
  • Adenomas are tumors that grow on glands (e.g. pituitary, adrenal, etc.).
  • Brain tumors are sometimes benign (e.g. acoustic schwannomas or meningiomas).
  • Lymphatic system tumors can be benign.
  • Osteomas are benign bone tumors.

Malignant tumors:

  • Carcinomas are malignant tumors that develop in the organ tissue lining or epithelial (skin) cells.3
  • Sarcomas are malignant tumors that form in the body’s connective tissue (fat, blood vessels, muscle, nerves, tendons, and joint lining).
  • Skin tumors like squamous cell carcinoma and melanoma (literal translation: black tumor) are malignant.
  • Brain tumors are sometimes malignant (e.g. glioblastomas and astrocytomas).
  • Bone tumors like osteosarcomas and chordomas are malignant.
  • Ovarian germ cell tumors are malignant.

Precancerous tumors:

Certain tumors fall in a classification middle ground known as “precancerous”. These tumors are technically benign, but can become malignant if left untreated. Preventive medicine plays a very important role in early detection of the following precancerous conditions:

  • Cervical dysplasia. These precancerous cells appear on the cervix and are frequently caused by HPV, a common sexually transmitted disease. Annual gynecological well checks can prevent the spread of these cells.
  • Ductal carcinoma in situ (DCIS). These breast tumors will become cancerous if not removed. Annual mammograms can catch DCIS in early stages.
  • Colon polyps. These growths in the large intestine or rectum can be precursors to colon cancer. Regular colonoscopies help significantly with early detection.
  • Actinic keratosis. These dry, scaly, rough patches of skin can become squamous cell carcinoma, a malignant skin cancer. Regular skin checks with a dermatologist will ensure any skin changes or cancers are detected early.

How are tumors diagnosed?

Medical imaging scans can detect masses that may require further testing. Tumors are ultimately diagnosed after a biopsy specimen is examined by an expert pathologist.

If symptoms have you worried or your doctor has recommended a diagnostic scan, head over to scan.com’s scan search tool to look for scan locations near you.


  1. clevelandclinic.org: Benign Tumor

  2. cancer.org: Signs and Symptoms of Cancer

  3. cancerresearchuk.org: Types of cancer

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