Adenoma and adenocarcinoma are both abnormal growths of glandular tissue. Both can occur anywhere where there is glandular tissue. Glands are either endocrine or exocrine. Endocrine glands release their secretions directly into the bloodstream. Exocrine glands release their secretions onto an epithelial surface via a duct system. Exocrine glands may be simple or complex. Simple exocrine glands consist of a short un-branched duct which opens on to an epithelial surface. Ex: duodenal glands. Complex glands may contain a branched duct system and acinar cell arrangement around each duct. Ex: Breast tissue. (Read more about Differences Between Endocrine and Exocrine Glands.) Glands can be divided into two categories according to their histological appearance. Tubular glands are normally a branched system of ducts in which the blind ends are secretory. Acinar glands have bulbous cell arrangements at the end of each duct. Pituitary prolactinoma is an example of an endocrine cancer. Breast adenocarcinoma is an example of an exocrine cancer.
Adenomas are benign non-invasive tumors. They may be microadenomas or macroadenomas. Microadenomas do not give rise to pressure effects because they do not press against adjacent structures. Macroadenomas give rise to pressure effects. Pituitary microadenomas may present as milk secretion from breasts without visual symptoms or headache. Pituitary microadenomas press on the optic chiasma and cause a headache and bitemporal hemianopia. Adenomas do not spread to distant locations via blood and lymph. They only show local effects, and even those are not common.
Adenocarcinoma can occur anywhere where there is glandular tissue. Adenocarcinoma is an uncontrolled abnormal proliferation of glandular tissue. Adenocarcinomas can spread locally by shooting off tendrils of cells through the basement membrane into adjacent tissues. Adenocarcinoma can spread with blood and lymph. Liver, bones, lung and peritoneum are known sites of metastatic deposits. Adenocarcinoma is, therefore, a malignant condition. It may present sometimes similar to adenomas but is different at the cellular level. Cancers are thought to be due to abnormal genetic signaling which promote uncontrolled cell division. There are genes called proto-oncogene, with a simple alteration, which can be cancer causing. Mechanisms of these alterations are not clearly understood. Two hit hypothesis is an example of such a mechanism. According to cancer invasiveness, spread and general patient outcome adenocarcinoma needs supportive therapy, radiotherapy, chemotherapy, surgical excision for cure and palliation.
What is the difference between Adenoma and Adenocarcinoma?
• Adenocarcinoma and adenoma may occur anywhere where there is glandular tissue.
• Adenomas are made up of cells with normal morphology without malignant markers.
• Adenocarcinoma cells show cellular atypia and mitotic bodies.
• Adenocarcinoma can metastasize frequently adenomas do not metastasize.
• Local excision is curative in adenomas while it may not be the case in adenocarcinoma.
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