SynonymsTumor, tumour, carcinocytes
Colon cancer 2.jpg
Colectomy specimen containing a malignant neoplasm, namely an invasive colorectal cancer (the crater-like, reddish, irregularly shaped tumor)

Neoplasia is a type of abnormal and excessive growth of tissue. The growth of a neoplasia is uncoordinated with that of the normal surrounding tissue, and it persists growing abnormally, even if the original trigger is removed.[1][2][3] This abnormal growth usually (but not always) forms a mass.[4] When it forms a mass, it may be called a tumor.

ICD-10 classifies neoplasms into four main groups: benign neoplasms, in situ neoplasms, malignant neoplasms, and neoplasms of uncertain or unknown behavior.[5] Malignant neoplasms are also simply known as cancers and are the focus of oncology.

Prior to the abnormal growth of tissue, as neoplasia, cells often undergo an abnormal pattern of growth, such as metaplasia or dysplasia.[6] However, metaplasia or dysplasia does not always progress to neoplasia.[1] The word is from Ancient Greek νέος- neo "new" and πλάσμα plasma "formation, creation".


A neoplasm can be benign, potentially malignant, or malignant (cancer).[7]

  • Benign tumors include uterine fibroids, osteophytes and melanocytic nevi (skin moles). They are circumscribed and localized and do not transform into cancer.[6]
  • Potentially-malignant neoplasms include carcinoma in situ. They are localised, do not invade and destroy but in time, may transform into a cancer.
  • Malignant neoplasms are commonly called cancer. They invade and destroy the surrounding tissue, may form metastases and, if untreated or unresponsive to treatment, will prove fatal.
  • Secondary neoplasm refers to any of a class of cancerous tumor that is either a metastatic offshoot of a primary tumor, or an apparently unrelated tumor that increases in frequency following certain cancer treatments such as chemotherapy or radiotherapy.
  • Rarely there can be a metastatic neoplasm with no known site of the primary cancer and this is classed as a cancer of unknown primary origin


Neoplastic tumors are often heterogeneous and contain more than one type of cell, but their initiation and continued growth is usually dependent on a single population of neoplastic cells. These cells are presumed to be clonal – that is, they are derived from the same cell,[8] and all carry the same genetic or epigenetic anomaly – evident of clonality. For lymphoid neoplasms, e.g. lymphoma and leukemia, clonality is proven by the amplification of a single rearrangement of their immunoglobulin gene (for B cell lesions) or T cell receptor gene (for T cell lesions). The demonstration of clonality is now considered to be necessary to identify a lymphoid cell proliferation as neoplastic.[9]

It is tempting to define neoplasms as clonal cellular proliferations but the demonstration of clonality is not always possible. Therefore, clonality is not required in the definition of neoplasia.

Neoplasia vs. tumor

Tumor (American English) or tumour (British English), Latin for swelling, one of the cardinal signs of inflammation, originally meant any form of swelling, neoplastic or not. Current English, however, both medical and non-medical, uses tumor as a synonym for a neoplasm (a solid or fluid-filled cystic lesion that may or may not be formed by an abnormal growth of neoplastic cells) that appears enlarged in size.[10][11] Some neoplasms do not form a tumor; these include leukemia and most forms of carcinoma in situ. Tumor is also not synonymous with cancer. While cancer is by definition malignant, a tumor can be benign, precancerous, or malignant.

The terms mass and nodule are often used synonymously with tumor. Generally speaking, however, the term tumor is used generically, without reference to the physical size of the lesion.[1] More specifically, the term mass is often used when the lesion has a maximal diameter of at least 20 millimeters (mm) in greatest direction, while the term nodule is usually used when the size of the lesion is less than 20 mm in its greatest dimension (25.4 mm = 1 inch).[12]

Other Languages
Afrikaans: Gewas
العربية: ورم
català: Neoplàsia
Cymraeg: Tiwmor
dansk: Neoplasi
eesti: Kasvaja
Ελληνικά: Νεόπλασμα
español: Neoplasia
euskara: Neoplasia
فارسی: نئوپلاسم
français: Néoplasie
Gaeilge: Sceachaill
galego: Neoplasia
한국어: 신생물
हिन्दी: फुलाव
Bahasa Indonesia: Neoplasma
עברית: נאופלזיה
Latina: Neoplasma
lietuvių: Neoplazma
magyar: Neoplasia
Nederlands: Neoplasie
norsk: Neoplasi
norsk nynorsk: Neoplasi
polski: Nowotwór
português: Neoplasma
српски / srpski: Неоплазма
srpskohrvatski / српскохрватски: Neoplazma
svenska: Neoplasi
اردو: نُفّاخ
中文: 贅生物