neoplasme

A neoplasm, commonly referred to as a tumor, is a new and abnormal growth of tissue that results from clonal expansion of cells with genetic or epigenetic alterations. Neoplasms grow in an autonomous fashion and persist beyond the normal regulatory controls that govern tissue homeostasis. They may form discrete masses or proliferate as diffuse proliferations and can be benign or malignant.

Neoplasms are broadly categorized by their biological behavior into benign and malignant. Benign neoplasms are typically well circumscribed, do not invade neighboring tissues, and do not metastasize; they often resemble the parent tissue (well-differentiated). Malignant neoplasms invade surrounding tissues and have the potential to spread (metastasize) to distant sites, which is the defining feature of cancer. Neoplasms are also grouped by tissue origin, such as carcinomas (epithelial origin), sarcomas (mesenchymal origin), hematologic malignancies (leukemias and lymphomas), and melanomas.

Most neoplasms arise through acquired genetic and epigenetic alterations that affect genes controlling cell growth, division, and death. Oncogenes, tumor suppressor genes, and DNA repair genes are frequently involved. Cumulative changes lead to hallmarks of malignant behavior, including sustained proliferative signaling, evasion of apoptosis, replicative immortality, induction of angiogenesis, and the ability to invade and metastasize.

Diagnosis relies on clinical assessment, imaging, and histopathologic examination of tissue samples. Treatment depends on type and behavior: benign neoplasms are often managed by observation or surgical excision; malignant neoplasms require multimodal therapy that may include surgery, radiotherapy, chemotherapy, targeted therapies, and immunotherapy. Prognosis depends on the neoplasm’s type, grade, stage, and molecular characteristics.