Benign tumor

Normal epidermis and dermis with intradermal nevus, 10x-cropped
Endoscopic image of sigmoid colon of a patient with familial adenomatous polyposis.
Benign (L) vs Malignant tumor (R).
Diagram showing two epithelial tumors. The upper tumor is a benign tumor that is non-invasive. Benign tumors are usually round in shape and encapsulated by fibrous connective tissue. The lower picture depicts a malignant tumor. It is irregularly shaped, vascular, and it is invasive, crossing the basement membrane.

Mass of cells that lacks the ability either to invade neighboring tissue or metastasize (spread throughout the body).

- Benign tumor

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Tendency of a medical condition to become progressively worse.

Malignant tumor (right) spreads uncontrollably and invades the surrounding tissues; benign tumor (left) remains self-contained from neighbouring tissue

A malignant tumor contrasts with a non-cancerous benign tumor in that a malignancy is not self-limited in its growth, is capable of invading into adjacent tissues, and may be capable of spreading to distant tissues.


Type of abnormal and excessive growth of tissue.

Colectomy specimen containing a malignant neoplasm, namely an invasive example of colorectal cancer (the crater-like, reddish, irregularly shaped tumor)
Neoplastic tumor of the cheek skin, here a benign neoplasm of the sweat glands called hidradenoma, which is not solid but is fluid-filled
Diagram illustrating benign neoplasms, namely fibroids of the uterus
The central role of DNA damage and epigenetic defects in DNA repair genes in malignant neoplasms
Longitudinally opened freshly resected colon segment showing a cancer and four polyps, plus a schematic diagram indicating a likely field defect (a region of tissue that precedes and predisposes to the development of cancer) in this colon segment. The diagram indicates sub-clones and sub-sub-clones that were precursors to the tumors.

ICD-10 classifies neoplasms into four main groups: benign neoplasms, in situ neoplasms, malignant neoplasms, and neoplasms of uncertain or unknown behavior.

Melanocytic nevus

Type of melanocytic tumor that contains nevus cells.

Lentiginous melanocytic naevus
Intradermal melanocytic nevus (dermatoscopic image)
Various differential diagnoses of pigmented skin lesions, including nevi, showing the relative incidence of biopsied lesions, and their malignancy potential.
Abraham Lincoln famously had a mole on his right cheek
A dermatoscope.
A modern polarized dermatoscope.
Small dermal nevus, with nests of nevus cells (arrows)

Acquired moles are a form of benign neoplasm, while congenital moles, or congenital nevi, are considered a minor malformation or hamartoma and may be at a higher risk for melanoma.


Disorder that results from excess growth hormone after the growth plates have closed.

Lower jaw showing the classic spacing of teeth due to acromegaly.
Frequent serum GH measurements in normal subjects (left panel) demonstrate that GH can fluctuate between undetectable levels most of the time interspersed with peaks of up to 30 μg/L (90 mIU/L); in acromegaly (right panel) GH hypersecretion is continuous with no undetectable levels.
Magnetic resonance image of a pituitary macroadenoma that caused acromegaly with compression of the optic chiasm
Site of action of the different therapeutic tools in acromegaly. Surgery, radiotherapy, somatostatin analogues and dopamine agonists act at the level of the pituitary adenoma, while GH receptor antagonists act in the periphery by blocking the growth hormone receptor and thus impairing the effects of GH on the different tissues.

In more than 95% of cases the excess production is due to a benign tumor, known as a pituitary adenoma.

Pituitary adenoma

Pituitary adenomas are tumors that occur in the pituitary gland.

Visual field loss in bitemporal hemianopsia: peripheral vision loss affecting both eyes, resulting from a tumor-typically a pituitary adenoma- putting pressure on the optic chiasm.
Morphological facial changes caused by acromegaly; frontal bossing, enlarged nose, prognathism and maxillary widening with separation of teeth and unseen, enlargement of the tongue (macroglossia).
Pituitary gland
Somatotroph pituitary adenoma, showing acidophilic cytoplasm
A silent gonadotroph pituitary adenoma which is, in this case, is eosinophilic (contrary to normal, basophilic, gonadotroph cells)
True null cell adenomas are typically composed of uniform, mildly atypical cells with chromophobic cytoplasm. This case has papillary architecture similar to gonadotroph adenomas.<ref>{{cite journal|last1=Drummond|first1=Juliana|last2=Roncaroli|first2=Federico|last3=Grossman|first3=Ashley B|last4=Korbonits|first4=Márta|title=Clinical and Pathological Aspects of Silent Pituitary Adenomas|journal=The Journal of Clinical Endocrinology & Metabolism|volume=104|issue=7|year=2019|pages=2473–2489|issn=0021-972X|doi=10.1210/jc.2018-00688|pmid=30020466|pmc=6517166}} - "This article has been published under the terms of the Creative Commons Attribution License (CC BY;"</ref>

Non-invasive and non-secreting pituitary adenomas are considered to be benign in the literal as well as the clinical sense; however a recent meta-analysis (Fernández-Balsells, et al. 2011) of available research has shown there are to date scant studies – of poor quality – to either support or refute this assumption.

Brain tumor

A brain tumor occurs when abnormal cells form within the brain.

Brain metastasis in the right cerebral hemisphere from lung cancer, shown on magnetic resonance imaging
The main areas of the brain and Limbic system
The meninges lie between the skull and brain matter. Tumors originating from the meninges are meningiomas.
A posterior fossa tumor leading to mass effect and midline shift
CT scan of a brain tumor, with its diameters marked as an X. There is hypoattenuating (dark) peritumoral edema in the surrounding white matter, with a "finger-like" spread.
Micrograph of an oligodendroglioma, a type of brain cancer. Brain biopsy. H&E stain
A brainstem glioma in four-year-old. MRI, sagittal, without contrast

There are two main types of tumors: malignant tumors and benign (non-cancerous) tumors.


Group of diseases involving abnormal cell growth with the potential to invade or spread to other parts of the body.

A coronal CT scan showing a malignant mesothelioma
Legend: → tumor ←, ✱ central pleural effusion, 1 & 3 lungs, 2 spine, 4 ribs, 5 aorta, 6 spleen, 7 & 8 kidneys, 9 liver
Symptoms of cancer metastasis depend on the location of the tumor.
The GHS Hazard pictogram for carcinogenic substances
Share of cancer deaths attributed to tobacco in 2016.
The incidence of lung cancer is highly correlated with smoking.
Cancers are caused by a series of mutations. Each mutation alters the behavior of the cell somewhat.
The central role of DNA damage and epigenetic defects in DNA repair genes in carcinogenesis
Chest X-ray showing lung cancer in the left lung
Three measures of global cancer mortality from 1990 to 2017
Engraving with two views of a Dutch woman who had a tumor removed from her neck in 1689
University of Florida Cancer Hospital
An invasive ductal carcinoma of the breast (pale area at the center) surrounded by spikes of whitish scar tissue and yellow fatty tissue
An invasive colorectal carcinoma (top center) in a colectomy specimen
A squamous-cell carcinoma (the whitish tumor) near the bronchi in a lung specimen
A large invasive ductal carcinoma in a mastectomy specimen

These contrast with benign tumors, which do not spread.


Pathogenic agent's spread from an initial or primary site to a different or secondary site within the host's body; the term is typically used when referring to metastasis by a cancerous tumor.

Illustration showing hematogenous metastasis
Cut surface of a liver showing multiple paler metastatic nodules originating from pancreatic cancer
Lymph node with almost complete replacement by metastatic melanoma. The brown pigment is focal deposition of melanin
Main sites of metastases for some common cancer types. Primary cancers are denoted by "...cancer" and their main metastasis sites are denoted by "...metastases".
Pulmonary metastases shown on Chest X-Ray
Cut surface of a humerus sawn lengthwise, showing a large cancerous metastasis (the whitish tumor between the head and the shaft of the bone)
Micrograph of thyroid cancer (papillary thyroid carcinoma) in a lymph node of the neck. H&E stain
CT image of multiple liver metastases
CT image of a lung metastasis
Metastasis proven by liver biopsy (tumor (adenocarcinoma)—lower two-thirds of image). H&E stain.
Metastatic cancer in the lungs
Metastases from the lungs to the brain
Metastases from the lungs to the pancreas

Metastasis is one of the hallmarks of cancer, distinguishing it from benign tumors.


Micrograph of a tubular adenoma (left of image), a type of colonic polyp and a precursor of colorectal cancer. Normal colorectal mucosa is seen on the right of the image. H&E stain.
MRI scan T1 with fat saturation - adrenal adenoma

An adenoma is a benign tumor of epithelial tissue with glandular origin, glandular characteristics, or both.

Tuberous sclerosis

A case of tuberous sclerosis showing facial angiofibromas in characteristic butterfly pattern
Computed tomography showing multiple angiomyolipomas of the kidney in a patient with lung lymphangioleiomyomatosis on CT: suspected TSC
The frequency of signs in children with TSC, grouped by age
TSC is inherited in an autosomal dominant fashion.
Désiré-Magloire Bourneville

Tuberous sclerosis complex (TSC) is a rare multisystem autosomal dominant genetic disease that causes non-cancerous tumours to grow in the brain and on other vital organs such as the kidneys, heart, liver, eyes, lungs and skin.