Colonic adenoma
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Adenoma

Adenoma refers to a collection of growths (-oma) of glandular origin. Adenomas can grow from many organs including the colon, adrenal, pituitary, thyroid, etc. These growths are benign, but some are known to have the potential, over time, to transform to malignancy (at which point they become known as adenocarcinoma.) more...

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Histopathology

Adenoma is a benign epithelial tumor arising in epithelium of mucosa (stomach, small intestine and bowel), glands (endocrine and exocrine) and ducts.

In hollow organs (digestive tract) the adenoma grows upwards into the lumen - adenomatous polyp or polypoid adenoma.

Depending on the type of the insertion base, adenoma may be pedunculated (lobular head with a long, slender stalk, covered by normal mucosa) or sessile (broad base).

The adenomatous proliferation is characterized by different degrees of cell dysplasia (atypia or loss of normal differentiation of epithelium): irregular cells with hyperchromatic nuclei, (pseudo)stratified nuclei, nucleolus, decreased mucosecretion and mitosis.

The architecture may be tubular, villous or tubulo-villous. Basement membrane and muscularis mucosae are intact.

Locations

Colon (D12)

Adenomas of the colon are quite prevalent. They are found commonly at colonoscopy. They are removed because of their tendency to become malignant and lead to colon cancer.

Adrenal (D350)

Adrenal adenomas are common (1 in 10 people have them), benign and asymptomatic. They are often found on CAT scans of the abdomen, usually not as the focus of investigation; they are usually incidental findings (incidentalomas). About one in 10,000 is malignant. Thus, a biopsy is rarely called for, especially if the lesion is homogeneous and smaller than 3 centrimeters. Follow-up images in three to six months can confirm the stability of the growth.

Malignant growth of the adrenal is called adrenal adenocarcinoma.

In patients with symptoms of Cushing's syndrome, adrenal adenomas are frequently the focus of glucocorticoid secretion. Surgical resection may be indicated; those unfit for surgery benefit from suppression of the cortisol production with ketoconazole or metyrapone.

Thyroid (D34)

About one in 10 people are found to have solitary thyroid nodules. Investigation is required because a small percentage of these are malignant. Biopsy usually confirms the growth to be an adenoma, but sometimes, excision at surgery is required, especially when the cells found at biopsy are of the follicular type.

Pituitary (D352)

Pituitary adenomas are commonly seen in 10% of the neurological patients. A lot of them remain undiagnosed. Treatment is usually surgical, to which patients generally respond well. The most common subtype, prolactinoma, is seen more often in women, and is frequently diagnosed during pregnancy as the hormone progesterone increases its growth. Medical therapy (bromocriptine) generally suppresses prolactinomas; progesterone antagonist therapy has not proven to be successful.

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Pleomorphic adenoma of the accessory parotid gland
From Ear, Nose & Throat Journal, 5/1/05 by Ryan F. Osborne

A 35-year-old woman was referred for evaluation of a right facial mass that had slowly enlarged over the previous 4 years. Her condition was thought to represent an infectious process, and antibiotics were prescribed. However, the mass continued to grow, causing the patient great concern about her appearance (figure 1). She denied any facial weakness, pain, numbness, or decrease in saliva. Magnetic resonance imaging (MRI) demonstrated a solid, well-circumscribed, 2.3 x 2.3 x 2.3-cm mass anterior to the border of the right parotid gland (figure 2). Fine-needle aspiration biopsy of the mass established the diagnosis of pleomorphic adenoma.

[FIGURES 1-2 OMITTED]

The patient was not in favor of an external approach because of cosmetic concerns. She instead opted for a transoral approach, and the mass was successfully resected. Final pathology revealed a completely excised 2.8 x 1.6 x 1.5-cm pleomorphic adenoma of an accessory parotid gland with an intact capsule. Examination 9 months postoperatively showed a well-healed oral mucosa, excellent facial nerve function and cosmesis, and no evidence of recurrence.

According to cadaveric studies, accessory parotid glands are found in approximately 21% of the population. (1) These small structures are typically noted clinically only in a diseased state. Accessory parotid glands, once believed to be simple extensions of the main parotid gland, are small, flat structures that function completely independently of the main parotid gland. The accessory parotid gland is located approximately 6 mm anterior to the main parotid gland, between the skin and the masseter muscle along an imaginary line that extends from the tragus to a point midway between the ala of the nose and the vermilion border of the lip. (2,3)

Anatomically, the accessory and main parotid glands share two important characteristics. First, both glands drain into Stensen's duct through at least one minor tributary (at times two or three minor tributaries in the case of the accessory gland). (1) The more important similarity is their intimate relationship with the facial nerve. In the main parotid gland, the trunk of the nerve courses deep to the superficial body of the gland. In the accessory parotid gland, the zygomatic and buccal rami run superficial to the gland.

According to the literature, benign tumors of the accessory parotid gland account for approximately 50 to 74% of all accessory parotid neoplasms; the rate of malignancy ranges from 26 to 50%. (4) In the main parotid gland, the rate of malignancy is far lower--approximately 18.5%. (4) In 1993, Toh et al theorized that this variation between the two glands was secondary to the difference in their tissue composition. (5) On histologic examination, the accessory parotid gland is made up of both serous and mucinous cells such as those seen in the submandibular gland. In contrast, the main parotid gland is predominantly serous. Despite this difference in histology, the most common benign tumor in both the accessory and main parotid gland remains the pleomorphic adenoma, a slow-growing, well-encapsulated neoplasm.

References

(1.) Frommer J. The human accessory parotid gland: Its incidence, nature, and significance. Oral Surg Oral Med Oral Pathol 1977;43:671-6.

(2.) Batsakis JG. Accessory parotid gland. Ann Otol Rhinol Laryngol 1988;97 (4 Pt 1):434-5.

(3.) Lewkowicz A, Levy Y, Zeltser R, et al. Accessory parotid gland masses. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2000; 89:610-12.

(4.) Perzik SL, White IL. Surgical management of the preauricular tumors of the accessory parotid apparatus. Am J Surg 1966:112; 498-503.

(5.) Toh H, Kodama J, Fukuda J, et al. Incidence and histology of human accessory parotid glands. Anat Rec 1993;236:586-90.

From the Department of Otolaryngology, Charles R. Drew University of Medicine and Science (Dr. Osborne, Dr. purohit, and Dr. Hamilton), and the Head and Neck Cancer Center, Cedars-Sinai Medical Center (Dr. Osborne), Los Angeles.

COPYRIGHT 2005 Medquest Communications, LLC
COPYRIGHT 2005 Gale Group

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