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Benign tumor

life science Maturity 11-13 Next article →

A benign tumor is a mass of cells that stays within a specific area. Unlike malignant tumors, which are cancerous, benign tumors do not invade neighboring tissues. They also do not undergo metastasis, which is the process of spreading to other parts of the body.

Types of tumor cells
Types of tumor cells

Most benign tumors consist of well-differentiated cells. This means the cells still closely resemble the original tissue from which they grew. They are often contained by a fibrous sheath, which is an outer layer of connective tissue. While the word "benign" suggests something harmless, these growths can still cause significant health problems. They are defined by what they are not: they are not malignant.

As a benign tumor grows, it can create what doctors call a mass effect. This occurs when the expanding mass physically presses against surrounding structures. This pressure can lead to several serious complications. It might cause nerve damage or reduce blood flow through a process called ischemia. In some cases, the pressure can lead to necrosis, which is the death of local tissue.

BENIGN AND MALIGNANT TUMOUR
BENIGN AND MALIGNANT TUMOUR

These effects are especially dangerous if the tumor grows inside an enclosed space. For example, a benign tumor inside the cranium, the bones, or the respiratory tract can be life-threatening. Some tumors also behave like the tissue they originated from, such as endocrine tumors that overproduce hormones.

Many benign tumors are caused by specific genetic mutations that disrupt normal cell growth. In Familial adenomatous polyposis, or FAP, mutations occur in the APC gene. This gene is a tumor suppressor, which means its job is to prevent uncontrolled growth. When the APC gene is inactivated, a protein called β-catenin builds up in the cells. This protein activates transcription factors known as T-cell factor (TCF) and lymphoid enhancer factor (LEF). These factors then turn on genes that cause cells to multiply rapidly.

Without medical intervention, these polyps in the colon can progress into cancer.

Other genetic conditions involve different sets of instructions within our DNA. Tuberous sclerosis complex (TSC) is caused by mutations in the TSC1 and TSC2 genes. These genes produce proteins called hamartin and tuberin. In a healthy body, these proteins inhibit a protein called mTOR, which regulates cell growth. When these tumor suppressors fail, mTOR activity increases and drives cell production. Similarly, Von Hippel–Lindau disease is caused by mutations in the VHL gene. The VHL protein normally helps manage how cells respond to low oxygen levels. When it is dysfunctional, it leads to the accumulation of a protein called HIF1α, which triggers the production of substances like VEGF to grow new blood vessels.

Benign tumors also vary greatly depending on the type of tissue involved. Lipomas are very common subcutaneous tumors made of adipocytes, or fat cells. They usually appear on the trunk or upper extremities and are most common in people aged 40 to 60. About 1 in every 1,000 people will develop a lipoma in their lifetime.

Types of tumor cells
Types of tumor cells

Bone tumors also present in distinct forms. An osteochondroma is a growth that forms a cartilage-capped projection on a bone. Enchondromas are tumors of hyaline cartilage found inside the bone, often showing a stippled appearance on X-rays. Giant cell tumors of bone frequently occur in the long bones of the limbs and can destroy nearby bone tissue.

Specific hormone-producing tumors can cause immediate and dangerous systemic effects. For instance, insulinomas produce large amounts of insulin, which leads to hypoglycemia, or low blood sugar. Pituitary adenomas can release various hormones that cause complex diseases. They might release growth hormone and insulin-like growth factor-1, resulting in acromegaly. They can also release prolactin, ACTH, or TSH, which leads to conditions like Cushing's disease or hyperthyroidism. These examples show that even if a tumor does not spread, its chemical output can be life-threatening.

Understanding the distinction between benign and malignant growth is vital for medical treatment. Many doctors use surgery to remove benign tumors to prevent them from causing harm. When a benign tumor is successfully removed, it usually does not return. However, if a tumor does reappear after surgery, it may indicate malignant transformation. This process, known as tumor progression, is when a benign growth changes into a cancerous one. By studying these processes, scientists gain a deeper understanding of how cellular signaling and genetic stability maintain human health.

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Familial adenomatous polyposis as seen on...
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Types of tumor cells.jpg
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