Benign
Encyclopedia
A benign tumor is a tumor
that lacks the ability to metastasize
. Common examples of benign tumors include moles
and uterine fibroids.
The term "benign
" implies a mild and nonprogressive disease. Indeed, many kinds of benign tumors are harmless to human health. However, some neoplasms defined as "benign tumors" because they lack the invasive properties of a cancer may still produce negative health effects. Examples of this include tumors which produce a "mass effect" (compression of vital organs such as blood vessels), or tumors of endocrine
tissues, which may overproduce certain hormone
s. Examples include thyroid adenoma
s, adrenocortical adenomas, and pituitary adenoma
s.
Benign tumors typically are surrounded by an outer surface (fibrous sheath) that inhibits their ability to behave in a malignant manner. Nonetheless, many types of benign tumors have the potential to become malignant and some types, such as teratoma
, are notorious for this.
is a common benign tumor of fat cells (lipocytes), and a chondroma
is a benign tumor of cartilage-forming cells (chondrocytes). Adenomas are benign tumors of gland-forming cells, and are usually specified further by their cell or organ of origin, as in hepatic adenoma (a benign tumor of hepatocyte
s, or liver
cells). There are a few cancers with 'benign-sounding' names which have been retained for historical reasons, including melanoma
(a cancer of pigmented skin cells, or melanocytes) and seminoma (a cancer of male reproductive cells).
In some cases, certain "benign" tumors may later give rise to malignant cancers, which result from additional genetic changes in a subpopulation of the tumor's neoplastic cells. A prominent example of this phenomenon is the tubular adenoma, a common type of colon polyp which is an important precursor to colon cancer. The cells in tubular adenomas, like most tumors which frequently progress to cancer, show certain abnormalities of cell maturation and appearance collectively known as dysplasia
. These cellular abnormalities are not seen in benign tumors that rarely or never turn cancerous, but are seen in other pre-cancerous tissue abnormalities which do not form discrete masses, such as pre-cancerous lesions of the uterine cervix
. Some authorities prefer to refer to dysplastic tumors as "pre-malignant", and reserve the term "benign" for tumors which rarely or never give rise to cancer.
is usually the most effective approach. Most benign tumors do not respond to chemotherapy
or radiation therapy
, although there are exceptions.
Tumor
A tumor or tumour is commonly used as a synonym for a neoplasm that appears enlarged in size. Tumor is not synonymous with cancer...
that lacks the ability to metastasize
Metastasis
Metastasis, or metastatic disease , is the spread of a disease from one organ or part to another non-adjacent organ or part. It was previously thought that only malignant tumor cells and infections have the capacity to metastasize; however, this is being reconsidered due to new research...
. Common examples of benign tumors include moles
Melanocytic nevus
A melanocytic nevus is a type of lesion that contains nevus cells .Some sources equate the term mole with "melanocytic nevus". Other sources reserve the term "mole" for other purposes....
and uterine fibroids.
The term "benign
Benignity
Benignity [from Latin benignus , from bonus + genus ] is a medical term used to describe a condition that is harmless...
" implies a mild and nonprogressive disease. Indeed, many kinds of benign tumors are harmless to human health. However, some neoplasms defined as "benign tumors" because they lack the invasive properties of a cancer may still produce negative health effects. Examples of this include tumors which produce a "mass effect" (compression of vital organs such as blood vessels), or tumors of endocrine
Endocrine system
In physiology, the endocrine system is a system of glands, each of which secretes a type of hormone directly into the bloodstream to regulate the body. The endocrine system is in contrast to the exocrine system, which secretes its chemicals using ducts. It derives from the Greek words "endo"...
tissues, which may overproduce certain hormone
Hormone
A hormone is a chemical released by a cell or a gland in one part of the body that sends out messages that affect cells in other parts of the organism. Only a small amount of hormone is required to alter cell metabolism. In essence, it is a chemical messenger that transports a signal from one...
s. Examples include thyroid adenoma
Thyroid adenoma
-Types:Almost all thyroid adenomas are follicular adenomas. Follicular adenomas can be described as "cold", "warm" or "hot" depending on their level of function...
s, adrenocortical adenomas, and pituitary adenoma
Pituitary adenoma
Pituitary adenomas are tumors that occur in the pituitary gland, and account for about 15% of intracranial neoplasms. Tumors which exceed 10 mm in size are defined as macroadenomas, and those smaller than 10 mm are referred to as microadenomas...
s.
Benign tumors typically are surrounded by an outer surface (fibrous sheath) that inhibits their ability to behave in a malignant manner. Nonetheless, many types of benign tumors have the potential to become malignant and some types, such as teratoma
Teratoma
A teratoma is an encapsulated tumor with tissue or organ components resembling normal derivatives of all three germ layers. There are rare occasions when not all three germ layers are identifiable...
, are notorious for this.
Classification
Benign neoplasms are typically composed of cells which bear a strong resemblance to a normal cell type in their organ of origin. These tumors are named for the cell or tissue type from which they originate, followed by the suffix "-oma" (but not -carcinoma, -sarcoma, or -blastoma, which are generally cancers). For example, a lipomaLipoma
A lipoma is a benign tumor composed of adipose tissue. It is the most common form of soft tissue tumor. Lipomas are soft to the touch, usually movable, and are generally painless. Many lipomas are small but can enlarge to sizes greater than six centimeters. Lipomas are commonly found in adults...
is a common benign tumor of fat cells (lipocytes), and a chondroma
Chondroma
A chondroma is a benign cartilaginous tumor, which is encapsulated with a lobular growing pattern.Tumor cells resemble normal cells and produce the cartilaginous matrix ....
is a benign tumor of cartilage-forming cells (chondrocytes). Adenomas are benign tumors of gland-forming cells, and are usually specified further by their cell or organ of origin, as in hepatic adenoma (a benign tumor of hepatocyte
Hepatocyte
A hepatocyte is a cell of the main tissue of the liver. Hepatocytes make up 70-80% of the liver's cytoplasmic mass.These cells are involved in:* Protein synthesis* Protein storage* Transformation of carbohydrates...
s, or liver
Liver
The liver is a vital organ present in vertebrates and some other animals. It has a wide range of functions, including detoxification, protein synthesis, and production of biochemicals necessary for digestion...
cells). There are a few cancers with 'benign-sounding' names which have been retained for historical reasons, including melanoma
Melanoma
Melanoma is a malignant tumor of melanocytes. Melanocytes are cells that produce the dark pigment, melanin, which is responsible for the color of skin. They predominantly occur in skin, but are also found in other parts of the body, including the bowel and the eye...
(a cancer of pigmented skin cells, or melanocytes) and seminoma (a cancer of male reproductive cells).
In some cases, certain "benign" tumors may later give rise to malignant cancers, which result from additional genetic changes in a subpopulation of the tumor's neoplastic cells. A prominent example of this phenomenon is the tubular adenoma, a common type of colon polyp which is an important precursor to colon cancer. The cells in tubular adenomas, like most tumors which frequently progress to cancer, show certain abnormalities of cell maturation and appearance collectively known as dysplasia
Dysplasia
Dysplasia , is a term used in pathology to refer to an abnormality of development. This generally consists of an expansion of immature cells, with a corresponding decrease in the number and location of mature cells. Dysplasia is often indicative of an early neoplastic process...
. These cellular abnormalities are not seen in benign tumors that rarely or never turn cancerous, but are seen in other pre-cancerous tissue abnormalities which do not form discrete masses, such as pre-cancerous lesions of the uterine cervix
Cervical intraepithelial neoplasia
Cervical intraepithelial neoplasia , also known as cervical dysplasia and cervical interstitial neoplasia, is the potentially premalignant transformation and abnormal growth of squamous cells on the surface of the cervix. CIN is not cancer, and is usually curable...
. Some authorities prefer to refer to dysplastic tumors as "pre-malignant", and reserve the term "benign" for tumors which rarely or never give rise to cancer.
Signs and symptoms
Benign tumors are very diverse, and may be asymptomatic or may cause specific symptoms depending on their anatomic location and tissue type. Symptoms or pathological effects of some benign tumors may include:- Bleeding or occult blood loss causing anemiaAnemiaAnemia is a decrease in number of red blood cells or less than the normal quantity of hemoglobin in the blood. However, it can include decreased oxygen-binding ability of each hemoglobin molecule due to deformity or lack in numerical development as in some other types of hemoglobin...
- Pressure causing pain or dysfunction
- Cosmetic changes
- Itching
- 'Hormonal syndromes' resulting from hormones secreted by the tumor
- Obstruction, e.g., of the intestinesBowel obstructionBowel obstruction is a mechanical or functional obstruction of the intestines, preventing the normal transit of the products of digestion. It can occur at any level distal to the duodenum of the small intestine and is a medical emergency...
- Compression of blood vessels or vital organs
Treatment
Many benign tumors do not need to be treated at all. If a benign tumor is causing symptoms, presents a health risk, or causes a cosmetic concern for the patient, surgerySurgery
Surgery is an ancient medical specialty that uses operative manual and instrumental techniques on a patient to investigate and/or treat a pathological condition such as disease or injury, or to help improve bodily function or appearance.An act of performing surgery may be called a surgical...
is usually the most effective approach. Most benign tumors do not respond to chemotherapy
Chemotherapy
Chemotherapy is the treatment of cancer with an antineoplastic drug or with a combination of such drugs into a standardized treatment regimen....
or radiation therapy
Radiation therapy
Radiation therapy , radiation oncology, or radiotherapy , sometimes abbreviated to XRT or DXT, is the medical use of ionizing radiation, generally as part of cancer treatment to control malignant cells.Radiation therapy is commonly applied to the cancerous tumor because of its ability to control...
, although there are exceptions.