What is defined as abnormal, disorganized "new growth" that can lead to the formation of a mass?

Neoplasia is defined as the process of abnormal, disorganized new growth of cells, which can lead to the formation of a mass or tumor. This can occur in various tissues and is characterized by a loss of control over the cell cycle, resulting in uncontrolled proliferation. Neoplastic growth can be benign (non-cancerous) or malignant (cancerous), and understanding this process is fundamental in the study of systemic diseases and oncology.

Dysplasia and metaplasia refer to changes in cell structure or type without necessarily leading to proliferation typical of neoplasia. Dysplasia involves abnormal cell growth that may suggest a precancerous condition but does not always result in a mass. Metaplasia is the replacement of one type of epithelial cell with another type, often in response to chronic irritation, but it does not imply new growth in the sense of tumor development. Hyperplasia involves an increase in the number of cells, leading to tissue enlargement, but this can occur in a controlled manner and does not equate to the disorganized and uncontrolled growth characteristic of neoplasia.