Patient With Duodenal Strictures and a Mass at the Head of the Pancreas.
On hospital day 13, the patient underwent a radical pancreaticoduodenectomy (Whipple procedure) for the duodenal stricture. The specimen received in pathology consisted of a 7.2-cm segment of duodenum with attached pancreas, measuring 6.5 x 5.8 x 3.2 cm. The duodenum was opened to reveal a dilated ampulla of Vater, measuring 1.1 cm in diameter. The mucosa adjacent to the ampulla was friable, tan to pink, and focally hemorrhagic. The portion of pancreas had a dilated pancreatic duct but no discrete masses. Microscopic examination of the friable tissue surrounding the ampulla showed a nodular proliferation of benign ductular elements lined by low cuboidal to columnar epithelium interspersed with hypertrophic smooth muscle fibers (Figure 3). The nuclei were basally oriented and no mitosis was noted (Figure 4).
What is your diagnosis?
Pathologic Diagnosis: Adenomyoma of the Ampulla and Distal Bile Duct
An adenomyoma is a benign lesion and a rare clinical finding. A "pseudotumor" of the extrahepatic biliary tract, the nodular lesion is characterized by tubular structures that are lined by columnar or cuboidal cells. The nuclei are basally located and monotonous, with no atypia or pleomorphism. Usually, no mitoses are seen. The connective tissue of the stroma contains whorls of interlaced smooth muscle bundles.
Approximately 90% of adenomyomas are located in the stomach, duodenum, and jejunum. Occasionally, they are found in other sites of the gastrointestinal tract, the thorax, the gallbladder, and in the biliary tree. The first case in the hepatic bile duct was reported by Dowdy et al in 1962. Since that time, 9 additional cases in the common and hepatic bile ducts have been reported. Of these 10 cases, 7 were found in the common bile duct.
Adenomyomas have been described by other synonyms, largely depending on the anatomic site. The microscopic appearance is similar to a gallbladder lesion known as adenomyomatous hyperplasia and to an intestinal lesion known as adenoleiomyomatous hyperplasia. Digestive tract adenomyomas are often confused with ectopic pancreatic tissue, myoepithelial hamartoma, fibroadenoma, and Brunner gland hyperplasia. Most adenomyomas do not contain pancreatic tissue, so they should not be confused with pancreatic heterotopia. Myoepithelial hamartoma is a misnomer, as hamartoma means an excessive overgrowth of mature normal indigenous cells within a tissue. A fibroadenoma does not describe the prominent smooth muscle component of the adenomyoma. Brunner gland hyperplasia usually denotes abundant Brunner glands with atrophic villi and crypts in the adjacent mucosa. Therefore, the term adenomyoma should be reserved for a distinct nodular lesion with a particular histopathologic pattern.
The symptoms of the adenomyoma depend on the location and the size of the neoplasm. Pain and dyspepsia, as in this case, is a common presenting complaint. The pain, usually colicky in the right upper quadrant, sometimes radiates to the back. Other symptoms include weight loss, fever, dysphagia, malaise, and anemia. Occasionally, the lesions are an incidental finding at surgery or during an autopsy.
The surgical management of an adenomyoma depends on its location. If the lesion is growing in the proximal part of the hepatic duct, its removal may be difficult or impossible without major hepatic resection. Distal common bile duct lesions can be removed by a radical pancreaticoduodenectomy (Whipple procedure), as in this case. The Whipple procedure is not recommended in benign distal or intrahepatic bile duct lesions owing to its higher morbidity and mortality, while not conferring any advantage over wide local excision.
In summary, adenomyoma should be included in the differential diagnosis of a mass at the head of the pancreas. The term adenomyoma should be reserved for a distinctive nodular lesion with the characteristic cuboidal or low columnar glands, interspersed in bundles of smooth muscle fibers. A Whipple procedure may be necessary to remove an adenomyoma of the common bile duct.
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Accepted for publication September 28, 2000.
From the Department of Pathology, Emory University, Atlanta, Ga (Dr Chand), and the Medical College of Georgia, Augusta (Dr Caudell).
Reprints not available from the author.
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|Author:||Chand, Eric M.; Caudell, Patricia|
|Publication:||Archives of Pathology & Laboratory Medicine|
|Date:||May 1, 2001|
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