Pleomorphic adenoma

src: upload.wikimedia.org

Pleomorphic adenoma is a benign salivary gland neoplasm commonly characterized by neoplastic proliferation of parenchyma gland cells along with the myoepithelial component, potentially malignant. It is the most common type of salivary gland tumor and the most common tumor of the parotid gland. This derives its name from Pleomorphism architecture (variable appearance) seen with a light microscope. It is also known as "mixed tumor, salivary gland type", which describes its pleomorphic appearance as opposed to the dual origin of the epithelial and myoepithelial elements.

Video Pleomorphic adenoma

Clinical presentation

Tumors are usually solitary and appear as a single nodular mass that grows slowly, painlessly. Isolated nodules are generally the result of a major nodule rather than a multinodular presentation. It usually moves unless found on the ceiling and can cause mandibular ramus atrophy while in the parotid gland. When found in parotid tails, it may appear as the eversion of the ear lobe. Although classified as benign, pleomorphic adenomas have the capacity to grow in large proportions and can undergo malignant transformation, to form ex-pleomorphic adenoma carcinoma, the risk increases over time (9.5% is likely to change to malignancy within 15 years). Although the "benign" tumor is aneuploid, it can recur after resection, it attacks adjacent normal tissue and distant metastases have been reported after a long time interval (10 years). These tumors most often appear in the shallow bottom pole. lobe of the gland, about 10% of the tumors appear in the deeper part of the gland. It occurs more frequently in women than in men, a ratio approaching 6: 4. The majority of lesions are found in patients in the fourth to sixth decades with an average age of about 43 years, but this is relatively common in young adults and is known to occur children.

Maps Pleomorphic adenoma

Histology

Morphological diversity is the most distinctive feature of this neoplasm. Histologically, it varies greatly in appearance, even in individual tumors. Classically it is biphasic and characterized by the mixing of epithelial and spindle-shaped myoepithelial elements in the variable background stroma that may be mucus, myxoid, cartilaginous or hyaline. The elements of the epithelium can be arranged in structures such as ducts, sheets, clumps and/or interlaced links and composed of polygonal, spindle or star-shaped cells (hence pleiomorphism). Metaplasia and squamous epithelial pearl areas can be found. Tumors are not enveloped, but are surrounded by fibrous pseudocapsules with varying thickness. The tumor extends through the normal gland parenchyma in the form of pseudopodia like a finger, but this is not a sign of malignant transformation.

Tumors often feature a typical chromosomal translocation between chromosomes # 3 and # 8. This causes the PLAG genes to be juxtaposed with genes for beta catenin. It activates the catenin path and leads to inappropriate cell division.

src: www.ajnr.org

Diagnosis

The diagnosis of salivary gland tumors utilizes tissue and radiographic sampling. Network sampling procedures include fine needle aspiration (FNA) and needle core biopsy (needle larger than FNA). Both of these procedures can be performed in an outpatient setting. Diagnostic imaging techniques for salivary gland tumors include ultrasound, computer tomography (CT) and magnetic resonance imaging (MRI).

A fine needle aspiration biopsy (FNA), operated in experienced hands, can determine whether the tumor is malignant with a sensitivity of about 90%. FNA can also distinguish primary salivary tumors from metastatic disease.

A core needle biopsy may also be performed in an outpatient setting. This is more invasive but more accurate than FNA with more than 97% diagnostic accuracy. Furthermore, the needle core biopsy allows more accurate tumor histological typing.

In terms of imaging studies, ultrasound can determine and characterize superficial parotid tumors. Some types of salivary gland tumors have certain sonographic characteristics in ultrasound. Ultrasound is also often used to guide core or FNA needle biopsies.

CT allows direct bilateral visualization of salivary gland tumors and provides information about overall dimensions and tissue invasion. CT is excellent for showing bone invasion. MRI delivers superior soft tissue delineation such as perineural invasion when compared with CT alone.

src: www.cairodiagnostics.com

Treatment

Overall, the mainstay of treatment for salivary gland tumors is surgical resection. Needle biopsy is highly recommended before surgery to confirm the diagnosis. More detailed surgical techniques and support for additional adjuvant radiotherapy depend on whether the tumor is malignant or benign.

Surgical treatment of parotid gland tumors is sometimes difficult, partly because of the anatomical relationship of facial nerves and parotid lodges, but also through an increased potential for postoperative relapse. Thus, early detection of a parotid gland tumor is essential in terms of prognosis after surgery.

Generally, benign tumors of the parotid gland treated with superficial (Patey surgery) or total parotidectomy with the latter become more commonly performed due to the high incidence of recurrence. Facial nerves should be maintained whenever possible. Benign benign submandibular glands are treated with simple excision with the preservation of the mandibular branches of the trigeminal nerve, the hypoglossal nerve, and the lingual nerve. Other benign tumors of the minor salivary glands are treated equally.

Malignant saliva tumors usually require extensive local resection of the primary tumor. However, if complete resection can not be achieved, adjuvant radiotherapy should be added to improve local control. This surgical treatment has many sequellae such as cranial nerve damage, Frey syndrome, cosmetic problems, etc.

Usually about 44% of patients have complete histologic removal of the tumor and this refers to the most significant survival rate.

src: www.missionforvisionusa.org

See also

• Warthin tumor - monomorphic adenoma
• Carcinoma
• Sialadenitis

src: images.radiopaedia.org

References

src: i.ytimg.com

External links

• Pleomrphic adenoma in GP Notebook, U.K
• Harvard
• CT and MR
• UK Parotis Tumor Support Forum

Source of the article : Wikipedia