adenocarcinoma n : malignant tumor originating in glandular epithelium [syn: glandular cancer, glandular carcinoma] [also: adenocarcinomata (pl)]

English

Noun

1. Any of several forms of carcinoma that originate in glandular tissue.

Adenocarcinoma is a cancer that originates in glandular tissue. This tissue is also part of a larger tissue category known as epithelial tissue. Epithelial tissue includes skin, glands and a variety of other tissue that lines the cavities and organs of the body. Epithelium is derived embryologically from ectoderm, endoderm and mesoderm. To be classified as adenocarcinoma, the cells do not necessarily need to be part of a gland, as long as they have secretory properties. This form of carcinoma can occur in some higher mammals, including humans. Well differentiated adenocarcinomas tend to resemble the glandular tissue that they are derived from, while poorly differentiated may not. By staining the cells from a biopsy, a pathologist will determine whether the tumor is an adenocarcinoma or some other type of cancer. Adenocarcinomas can arise in many tissues of the body due to the ubiquitous nature of glands within the body. While each gland may not be secreting the same substance, as long as there is an exocrine function to the cell, it is considered glandular and its malignant form is therefore named adenocarcinoma. Endocrine gland tumors, such as a VIPoma, an insulinoma, a pheochromocytoma, etc, are typically not referred to as adenocarcinomas, but rather, are often called neuroendocrine tumors. If the glandular tissue is abnormal, but benign, it is said to be an adenoma. Benign adenomas typically do not invade other tissue and rarely metastasize. Malignant adenocarcinomas invade other tissues and often metastasize given enough time to do so.

Diagnostic significance

A diagnosis of adenocarcinoma which is not further described, known as adenocarcinoma not otherwise specified and adenocarcinoma NOS, is significant because it indicates a cancerous process is present. However, it is not very useful for treatment decisions and prognosis, as these are determined by the tissue from which the tumour cells arose, i.e. the tissue of origin; an adenocarcinoma of the colon has a different prognosis and treatment than an adenocarcinoma of the ovary.

Adenocarcinoma not otherwise specified is often a preliminary diagnosis and can frequently be clarified by a pathologist with the use of immunohistochemistry.

Cancer for which a primary site cannot be found is called cancer of unknown primary.

Histopathology

Examples of tissues where adenocarcinomas may arise:

• breast
• colon * stomach
• pancreas (99% of pancreatic cancers are ductal adenocarcinomas)
• cervix
• vagina
• urachus

Etymology

The term adenocarcinoma is derived from 'adeno' meaning 'pertaining to a gland' and 'carcinoma', which describes a cancer that has developed in the epithelial cells.

References