A neoplasm () is a type of abnormal and excessive growth of tissue. The process that occurs to form or produce a neoplasm is called neoplasia. The growth of a neoplasm is uncoordinated with that of the normal surrounding tissue, and persists in growing abnormally, even if the original trigger is removed. This abnormal growth usually forms a mass, when 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. 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. However, metaplasia or dysplasia does not always progress to neoplasia and can occur in other conditions as well. The word is from Ancient Greek νέος- neo new and πλάσμα plasma formation, creation. Types
A neoplasm can be benign, potentially malignant, or malignant (cancer). Benign tumors include uterine fibroids, osteophytes and melanocytic nevi (skin moles). They are circumscribed and localized and do not transform into cancer. 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 generally prove fatal.
The Roman medical encyclopedist Celsus (c. 30 BC–38 AD) described the four cardinal signs of acute inflammation as tumor, dolor, calor, and rubor (swelling, pain, increased heat, and redness). (His treatise, De Medicina, was the first medical book printed in 1478 following the invention of the movable-type printing press.) In contemporary English, the word tumor is often used as a synonym for a cystic (liquid-filled) growth or solid neoplasm (cancerous or non-cancerous), with other forms of swelling often referred to as "swellings".Related terms occur commonly in the medical literature, where the nouns tumefaction and tumescence (derived from the adjective tumescent) are current medical terms for non-neoplastic swelling. This type of swelling is most often caused by inflammation caused by trauma, infection, and other factors. Tumors may be caused by conditions other than an overgrowth of neoplastic cells, however. Cysts (such as sebaceous cysts) are also referred to as tumors, even though they have no neoplastic cells. This is standard in medical-billing terminology (especially when billing for a growth whose pathology has yet to be determined). See also
Somatic evolution in cancer
List of biological development disorders
Epidemiology of cancer
Pleomorphism

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