Knowledge of Tumors and the Distinction Between Benign and Malignant Tumors

A tumor (neoplasm) is a new growth formed when, under the action of various tumorigenic factors, the genetic regulation of cells in local tissue becomes severely disordered, leading to clonal abnormal proliferation; it often manifests as a local mass in the body. However, certain neoplastic diseases do not necessarily form a local mass, such as leukemia. Conversely, lesions that clinically present as a mass are not necessarily tumors, such as inflammatory pseudotumor.

The gold standard for diagnosing a tumor is the histopathological finding of atypia in tumor tissue and cells. Tumor atypia refers to the fact that tumor tissue differs, to varying degrees, from the normal tissue of origin in both cellular morphology and tissue structure.

Tumors grow in four ways: expansive growth, infiltrative growth, exophytic growth, and endophytic growth. Spread occurs in two ways: direct extension and metastasis; metastasis is further divided into lymphatic metastasis, hematogenous metastasis, and seeding (implantation) metastasis.

When a malignant tumor of an intrabody-cavity organ extends to the surface of the organ, tumor cells may detach and, like sowing seeds, implant on the surface of the body cavity or other organs, forming multiple metastatic tumors; this is called seeding (implantation) metastasis.

Benign tumors generally cause little harm to the body, are easy to treat, and have a good prognosis; malignant tumors cause greater harm, require complex treatment measures, and have a poorer prognosis.

The distinction between benign and malignant tumors is mainly reflected in the following aspects:

Degree of differentiation: benign tumors are well differentiated with little atypia, resembling the morphology of the original tissue; malignant tumors are poorly differentiated with marked atypia, differing greatly from the morphology of the original tissue.

Mitotic figures: benign tumors have no or few mitotic figures, and no pathological mitotic figures are seen; malignant tumors show numerous mitotic figures, and pathological mitotic figures are visible.

Growth rate: benign tumors grow slowly; malignant tumors grow relatively quickly.

Growth pattern: benign tumors are mostly expansile and exophytic, often forming a capsule, usually with a clear boundary from surrounding tissue, and are generally movable; malignant tumors are mostly infiltrative and exophytic, without a capsule, generally with an unclear boundary from surrounding tissue, and are usually not movable.

Metastasis: benign tumors rarely metastasize; malignant tumors may metastasize.

Recurrence: benign tumors generally do not recur; malignant tumors carry a very high recurrence risk.

Effect on the body: benign tumors have a minor effect, mainly local compression or obstruction; malignant tumors have a major effect, and in addition to compression and obstruction, can destroy tissue at the primary and metastatic sites, causing necrosis, bleeding, secondary infection, and even cachexia.

Because final examinations are under way and I have no time for writing, this article is only an outline; I will continue to complete it when I have time later.