Neoplasm means new growth that ignores the tissue’s usual plan
A neoplasm is abnormal, excessive tissue growth that stays uncoordinated with its neighbours and keeps expanding even after the trigger is gone, usually as a mass called a tumour. ICD-10 sorts them into benign, in situ, malignant, and uncertain behaviour—malignancies are cancers.
The Greek roots mean new formation. Before frank neoplasia, cells may show metaplasia or dysplasia, yet those patterns need not advance to tumour. Benign examples such as uterine fibroids, bone spurs, and moles stay local and do not become cancer. Carcinoma in situ is potentially malignant: confined now, able to transform later. Malignant neoplasms invade, may metastasise, and often kill if untreated or untreatable.
Secondary neoplasms may be metastases or later tumours linked to prior chemotherapy or radiotherapy. Rarely, metastatic disease appears with no found primary—cancer of unknown primary origin. Growth usually depends on a monoclonal neoplastic population sharing one genetic or epigenetic lesion, even when the mass looks cellularly mixed.
Tumour once meant any swelling, one of inflammation’s cardinal signs; modern English often equates it with neoplasm, solid or cystic. Mass typically labels lesions at least twenty millimetres across; nodule is reserved for smaller ones, though everyday speech blurs the sizes.
Not every lump is a neoplasm. Sebaceous cysts, breast cysts that often appear in pregnancy, encapsulated haematomas, keloid scar overgrowths and granulomas can all present as tumours while carrying no malignant potential. For cancers proper, DNA damage is regarded as the primary underlying cause. People who inherit a defect in any of 34 DNA repair genes face raised risk, a few such mutations approaching a certain lifetime chance of cancer, yet about 70 percent of malignant neoplasms are sporadic, with no hereditary component. In many of those, repair genes are switched off epigenetically rather than mutated; such defects in BRCA1, MLH1, MGMT and others turn up at frequencies from 13 to 100 percent. Once formed, a cancer's genome is usually unstable, so it keeps evolving and throwing off subclones.
Source: Neoplasm
