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Polymorphous Low-Grade Adenocarcinoma

Synonyms of Polymorphous Low-Grade Adenocarcinoma

  • Lobular Carcinoma of the Minor Salivary Glands
  • Low-Grade Papillary Carcinoma of the Palate
  • Pleomorphic Adenoma
  • PLGA
  • Terminal Duct Carcinoma

Disorder Subdivisions

  • No subdivisions found.

General Discussion

Polymorphous low-grade adenocarcinoma (PLGA) is a rare tumor of the salivary glands that is limited, to a great extent, to the minor salivary glands and commonly, but not exclusively, localized in the palate of the mouth. The major salivary glands are the parotid glands (at the side of the face, below the ears), the sublingual glands (below the tongue), and the submandibular glands (below the lower jaw). As the name suggests, each of the major salivary glands is of substantial size and visible to the naked eye. There are about 600 to 1,000 minor salivary glands that are microscopic in size. These minor salivary glands are found in the lining (mucosa) of the lips, tongue, and hard and soft palate, as well as inside the nose, cheeks, and sinuses.

Less than one (1%) per cent of all cancers reported in the USA are salivary cancers and, of these, 80% begin in the parotid glands, and about 15% begin in the submandibular glands, leaving only 5% that begin in the sublingual and minor salivary glands. Most of the tumors that start in the major salivary glands turn out to be benign, while most, but not all, of the cancers that start in the minor salivary glands turn out to be malignant.


A lump or mass in the palate or near any of the salivary glands should be seen by a physician as soon as possible. A lingering pain in the area of the salivary glands is a signal to see a physician. A change in the size and/or shape of one of the salivary glands (asymmetry) may be a sufficient reason to see a doctor. Unexplained bleeding in the mouth is also a symptom warranting attention, and any persistent numbness on any part of the face or a weakening of the muscles on one side of the face should be brought to the attention of a physician. Early diagnosis and treatment are important.


Why a normal cell becomes malignant is not yet fully understood.

Affected Populations

In most instances PLGA affects people in their middle age. The median age at which patients are diagnosed is 57 years, with a range of from 22 to 71 years. For reasons that are unknown, this disease affects slightly more women than men.

Related Disorders

Acinic cell carcinoma
Acinic cell carcinoma is a rare salivary gland cancer that represents approximately 6-10% of all salivary gland cancers. The National Cancer Institute reported 1,353 cases of acinic cell carcinoma of the head and neck in the U.S. from 1985 to 1995 or about 135 cases per year. They make up approximately 4% of all minor and 2-4% of all major salivary gland tumors. Acinic cell carcinomas arise most frequently in the parotid gland (86.3% in largest study). Other sites of primary tumors have included the submandibular gland and other major and minor salivary glands.

Standard Therapies

The diagnosis of PLGA may be suspected on history and clinical examination, but can be confirmed only by biopsy of the affected tissue.

The primary mode of treatment for low-grade stage I tumors of the salivary gland is surgery (resection). Radiation therapy may be prescribed as a supplement in some cases. Palate rehabilitation may be needed depending on the size of the tumor.

Investigational Therapies

Information on current clinical trials is posted on the Internet at All studies receiving U.S. government funding, and some supported by private industry, are posted on this government web site.

For information about clinical trials being conducted at the NIH Clinical Center in Bethesda, MD, contact the NIH Patient Recruitment Office:

Tollfree: (800) 411-1222
TTY: (866) 411-1010

For information about clinical trials sponsored by private sources, contact:

Polymorphous Low-Grade Adenocarcinoma Resources



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Edwards PC, Bhuiya T, Kelsch RD. C-kit expression in the salivary gland neoplasms adenoid cystic carcinoma, polymorphous low-grade adenocarcinoma, and monomorphic adenoma. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2003;95:586-93.

Young S, Leon M, Talerman A, et al. Polymorphous low-grade adenocarcinoma of the vulva and vagina: a tumor resembling adenoid cystic carcinoma. Int J Surg Pathol. 2003;11:43-49.

Sahai K, Kapila K, Dahiya S, et al. Fine needle aspiration cytology of minor salivary gland tumours of the palate. Cytopathology. 2002;13:309-16.

Simpson RH, Pereira EM, Ribeiro AC, et al. Polymorphous low-grade adenocarcinoma of the salivary glands with transformation to high-grade carcinoma. Histopathology. 2002;41:250-59.

Darling MR, Schneider JW, Phillips VM. Polymorphous low-grade adenocarcinoma and adenoid cystic carcinoma: a review and comparison of immunohistochemical markers. Oral Oncol. 2002;38:641-45.

Araujo VC, Loducca SV, Sousa SO, et al. The cribriform features of adenoid cystic carcinoma and polymorphous low-grade adenocarcinoma: cytokeratin and integrin expression. Ann Diagn Pathol. 2001;5:330-34.

Martins C, Fonseca I, roque L, et al. Cytogenic similarities between two types of salivary gland carcinomas: adenoid cystic carcinoma and polymorphous low-grade adenocarcinoma. Cancer Genet Cytogenet. 2001;128:130-36.

Evans HL, Luna MA. Polymorphous low-grade adenocarcinoma: a study of 40 cases with long-term follow up and an evaluation of the importance of the papillary area. Am J Surg Pathol. 2000;24:1319-28.

Asdornato MC, Penna K, Vinoski M. Polymorphous low-grade adenocarcinoma of the oral cavity. N Y State Dent J. 2000;66:28-32.

Nicol KK, Iskander SS. Lobular carcinoma of the breast metastatic to the oral cavity mimicking polymorphous low-grade adenocarcinoma of the minor salivary glands. Arch Pathol Lab Med. 2000;124:157-59.

Salivary Gland Cancer (PDQ®). National Cancer Institute. [Patient Version]. Last Modified: 11/19/2003.

Salivary Gland Cancer (PDQ®). National Cancer Institute. [Health Professional Version]. Last Modified: 12/22/2003.

Detailed Guide: Salivary Gland Cancer. American Cancer Society. ©2004. Various.

Atlas of Head and Neck Pathology: Polymorphous Low-Grade Adenocarcinoma. nd 4pp.

Polymorphous Low Grade AdenoCA. The Doctor’s Doctor. nd. 11pp.

What is Salivary Gland Cancer? ©2004 Yahoo! Inc. various.

The information in NORD’s Rare Disease Database is for educational purposes only. It should never be used for diagnostic or treatment purposes. If you have questions regarding a medical condition, always seek the advice of your physician or other qualified health professional. NORD’s reports provide a brief overview of rare diseases. For more specific information, we encourage you to contact your personal physician or the agencies listed as “Resources” on this report.

Report last updated: 2007/08/07 00:00:00 GMT+0

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