Adenocarcinoma is a type of cancerous tumor that can occur in several parts of the body. It is defined as neoplasia of epithelial tissue that has glandular origin, glandular characteristics, or both. Adenocarcinomas are part of the larger grouping of carcinomas, but are also sometimes called by more precise terms omitting the word, where these exist. Thus invasive ductal carcinoma, the most common form of breast cancer, is adenocarcinoma but does not use the term in its name—however, esophageal adenocarcinoma does to distinguish it from the other common type of esophageal cancer, esophageal squamous cell carcinoma. Several of the most common forms of cancer are adenocarcinomas, and the various sorts of adenocarcinoma vary greatly in all their aspects, so that few useful generalizations can be made about them.
The parotid gland is a major salivary gland in many animals. In humans, the two parotid glands are present on either side of the mouth and in front of both ears. They are the largest of the salivary glands. Each parotid is wrapped around the mandibular ramus, and secretes serous saliva through the parotid duct into the mouth, to facilitate mastication and swallowing and to begin the digestion of starches. There are also two other types of salivary glands; they are submandibular and sublingual glands. Sometimes accessory parotid glands are found close to the main parotid glands.
An adenoma is a benign tumor of epithelial tissue with glandular origin, glandular characteristics, or both. Adenomas can grow from many glandular organs, including the adrenal glands, pituitary gland, thyroid, prostate, and others. Some adenomas grow from epithelial tissue in nonglandular areas but express glandular tissue structure. Although adenomas are benign, they should be treated as pre-cancerous. Over time adenomas may transform to become malignant, at which point they are called adenocarcinomas. Most adenomas do not transform. However, even though benign, they have the potential to cause serious health complications by compressing other structures and by producing large amounts of hormones in an unregulated, non-feedback-dependent manner. Some adenomas are too small to be seen macroscopically but can still cause clinical symptoms.
Apocrine is a term used to classify the mode of secretion of exocrine glands. In apocrine secretion, secretory cells accumulate material at their apical ends, and this material then buds off from the cells, forming extracellular vesicles. The secretory cells therefore lose part of their cytoplasm in the process of secretion.
Pleomorphic adenoma is a common benign salivary gland neoplasm characterised by neoplastic proliferation of epithelial (ductal) cells along with myoepithelial components, having a malignant potentiality. It is the most common type of salivary gland tumor and the most common tumor of the parotid gland. It derives its name from the architectural Pleomorphism seen by light microscopy. It is also known as "Mixed tumor, salivary gland type", which refers to its dual origin from epithelial and myoepithelial elements as opposed to its pleomorphic appearance.
GTPase HRas, from "Harvey Rat sarcoma virus", also known as transforming protein p21 is an enzyme that in humans is encoded by the HRAS gene. The HRAS gene is located on the short (p) arm of chromosome 11 at position 15.5, from base pair 522,241 to base pair 525,549. HRas is a small G protein in the Ras subfamily of the Ras superfamily of small GTPases. Once bound to Guanosine triphosphate, H-Ras will activate a Raf kinase like c-Raf, the next step in the MAPK/ERK pathway.
Canalicular adenoma is a benign, epithelial salivary gland neoplasm arranged in interconnecting cords of columnar cells. This is a very rare benign neoplasm, that makes up about 1% of all salivary gland tumors, or about 4% of all benign salivary gland tumors.
Polymorphous low-grade adenocarcinoma (PLGA) is a rare, asymptomatic, slow-growing malignant salivary gland tumor. It is most commonly found in the palate.
Acinic cell carcinoma is a malignant tumor representing 2% of all salivary tumors. 90% of the time found in the parotid gland, 10% intraorally on buccal mucosa or palate. The disease presents as a slow growing mass, associated with pain or tenderness in 50% of the cases. Often appears pseudoencapsulated.
Salivary gland tumours, also known as mucous gland adenomas or neoplasms, are tumours that form in the tissues of salivary glands. The salivary glands are classified as major or minor. The major salivary glands consist of the parotid, submandibular, and sublingual glands. The minor salivary glands consist of 800 to 1000 small mucus-secreting glands located throughout the lining of the oral cavity. Patients with these types of tumours may be asymptomatic.
Lobular carcinoma in situ (LCIS) is an incidental microscopic finding with characteristic cellular morphology and multifocal tissue patterns. The condition is a laboratory diagnosis and refers to unusual cells in the lobules of the breast. The lobules and acini of the terminal duct-lobular unit (TDLU), the basic functional unit of the breast, may become distorted and undergo expansion due to the abnormal proliferation of cells comprising the structure. These changes represent a spectrum of atypical epithelial lesions that are broadly referred to as lobular neoplasia (LN).
Syringocystadenoma papilliferum is a rare non-malignant adnexal neoplasm that develops from apocrine or eccrine sweat glands and can be identified histologically by cystic, papillary, and ductal invaginations into the dermis lined by double-layered outer cuboidal and luminal high columnar epithelium and connected to the epidermis.
Myoepithelioma of the head and neck, also myoepithelioma, is a salivary gland tumour of the head and neck that is usually benign. When malignant, which is exceedingly rare, they are known as malignant myoepithelioma or Myoepithelial carcinoma, and they account for 1% of the salivary tumors with poor prognosis.
Epithelial-myoepithelial carcinoma (EMCa) is a rare malignant tumour that typically arises in a salivary gland and consists of both an epithelial and myoepithelial component. They are predominantly found in the parotid gland and represent approximately 1% of salivary gland tumours.
Hyalinizing clear cell carcinoma (HCCC) is a rare malignant salivary gland tumour, with a good prognosis, that is usually found on the tongue or palate.
A sialoblastoma is a low-grade salivary gland neoplasm that recapitulates primitive salivary gland anlage. It has previously been referred to as congenital basal cell adenoma, embryoma, or basaloid adenocarcinoma. It is an extremely rare tumor, with less than 100 cases reported worldwide.
A ceruminous adenoma is a benign glandular neoplasm which arises from the ceruminous glands located within the external auditory canal. These glands are found within the outer one third to one half of the external auditory canal, more common along the posterior surface; therefore, the tumor develops within a very specific location.
Carcinoma ex pleomorphic adenoma is a type of cancer typically found in the parotid gland. It arises from the benign tumour pleomorphic adenoma.
Sclerosing polycystic adenosis is a rare salivary gland tumor first described in 1996 by Dr. Brion Smith. The major salivary glands, specifically the parotid gland and the submandibular gland, are affected most commonly. Patients usually come to clinical attention with a mass or swelling in their salivary glands in the 5th decade of life, with females affected much more commonly than males. Nearly all of the cases reported so far have a benign behavior, although there is a single case that has had an associated malignant transformation.
Pure apocrine carcinoma of the breast (PACB) is a rare carcinoma derived from the epithelial cells in the lactiferous ducts of the mammary gland. The mammary gland is an apocrine gland. Its lactiferous ducts have two layers of epithelial cells, a luminal layer which faces the duct's lumen and a basal layer which lies beneath the luminal layer. There are at least 4 subtypes of epithelial cells in these ducts: luminal progenitor cells and luminal mature cells which reside in the luminal layer and mammary stem cells and basal cells which reside in the basal layer. Examination of the genes expressed in PACB cancer cells indicate that most of these tumors consist of cells derived from luminal cells but a minority of these tumors consist of cells derived from basal cells.
