Malignant

In medicine, malignant is a clinical term that is used to describe a clinical course that progresses rapidly to death. It is typically applied to neoplasms that show aggressive behavior characterised by local invasion or distant metastasis.

The change of cells from benign to malignant behavior is called malignant transformation. Usually this diagnosis is made by pathologic examination of tissues. However, often the physician during the history and physical examination can find that there have been changes in size or patient sensation and upon direct examination that there has been a change in the lesion itself.

Malignant transformation is a synonym for progression to malignancy. Transformation may take place as a primary or a secondary process.

Although malignant transformation may occur because of changes within the cell, it can be induced by inorganic toxic substances such as cadmium or arsenite and organics such as tobacco-specific nitrosamines. It is also thought that some malignant transformation is due to viruses such as the Epstein-Barr virus.

Malignant qualities in cancer may be due to still multiplying cells, or cells that break off from the main tumour and enter the blood stream, being transported elsewhere where the cells that broke off are able to reproduce further, thus spreading the cancer.

Risk assessments can be done and are known for certain populations. One of the better known of these progression and risks is the progression of a nevus to melanoma.