| Abstract|| |
Adenomyoma can be misdiagnosed as an adenocarcinoma, leading to needless and extensive surgical resections. A 45-year-old woman presented with right hypochondrial pain. Magnetic resonance imaging showed a choledochal cyst. Excision of choledochal cyst with Roux-en-Y hepaticojejunostomy was performed. A segment of dilated common bile duct and an attached nodule was received. Sections from the choledochal cyst showed a cyst wall composed of dense fibrous tissue lined by partially ulcerated columnar epithelium. Sections from the nodule showed interlacing whorls of smooth muscle bundles with entrapped glands. The glands were lined by cuboidal to columnar cells without nuclear atypia. This was recognized as an adenomyoma. To the best of our knowledge, this is the first reported case in which an adenomyoma was found associated with a type 1 choledochal cyst. A review of the existing literature and discussion of theories of genesis and the diagnostic pitfalls are presented.
Keywords: Adenomyoma, common bile duct, choledochal cyst, smooth muscle
|How to cite this article:|
Singh DK, Rastogi A, Sakhuja P, Gondal R. Adenomyoma of common bile duct arising in a type I choledochal cyst. Indian J Pathol Microbiol 2011;54:365-7
|How to cite this URL:|
Singh DK, Rastogi A, Sakhuja P, Gondal R. Adenomyoma of common bile duct arising in a type I choledochal cyst. Indian J Pathol Microbiol [serial online] 2011 [cited 2020 Jul 9];54:365-7. Available from: http://www.ijpmonline.org/text.asp?2011/54/2/365/81640
| Introduction|| |
Adenomyoma of the common bile duct (CBD) is a rare lesion which may be misdiagnosed as an adenocarcinoma preoperatively or on intraoperative frozen section examination, leading to unnecessary and extensive surgical resections. ,,,, We present the first reported case of adenomyoma of CBD arising in a choledochal cyst, discuss the theories of genesis, diagnostic pitfalls and treatment options.
| Case Report|| |
A 45-year-old woman presented with right hypochondrial pain since 1.5 years. She had a cholecystectomy done 15 years back for gallstones. Routine laboratory investigations were within normal limits. Ultrasound abdomen, magnetic resonance imaging (MRI) and magnetic resonance cholangiopancreaticography (MRCP) were suggestive of choledochal cyst type I. Papilla of Vater and all the abdominal organs were normal. Excision of choledochal cyst with Roux-en-Y hepaticojejunostomy was performed. Surgical specimen received was a 2.5 cm segment of CBD, 2 cm of which was cystically dilated. A circumscribed nodular lesion measuring 1.2 cm in diameter was attached to the mid-portion of the cyst. Cut surface of the nodule was homogeneous and grayish-white [Figure 1]. Sections from the choledochal cyst showed a dense fibro-collagenous wall lined by partially ulcerated columnar epithelium with small wisps of smooth muscle and few small foci of chronic inflammatory cells. Sections from the nodule revealed a circumscribed lesion composed of interlacing whorls of smooth muscle bundles with entrapped singly scattered and groups of glands lined by cuboidal to columnar cells [Figure 2]a. The cells had basally located nuclei which did not reveal any hyperchromasia or pleomorphism [Figure 2]B. Mitosis was not discernible. There were no areas of necrosis or hemorrhage. A histological diagnosis of choledochal cyst with adenomyoma of CBD was made.
|Figure 1: Gross appearance of adenomyoma is of a circumscribed nodular lesion with a grayish-white surface and foci of spongy spaces without hemorrhage and necrosis (large arrow). The adenomyoma was attached to the wall of choledochal cyst (arrow head). The wall of the choledochal cyst is marked by small arrow|
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|Figure 2: (a) Microscopic examination shows a circumscribed lesion composed of whorls of smooth muscle bundles with entrapped glands lined by cuboidal to columnar cells (hematoxylin and eosin, ×100). (b) The glands showed cells with basal nuclei without hyperchromasia or pleomorphism (hematoxylin and eosin, ×400)|
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| Discussion|| |
Approximately 90% of adenomyomas occur in the stomach, gallbladder, duodenum and jejunum. Adenomyomas of the extrahepatic biliary tract are rare and occur in the gallbladder and occasionally in the papilla of Vater. CBD is a very rare site for this lesion, as was seen in our case. ,,,
Adenomyoma of CBD may be clinically asymptomatic or present with jaundice, right abdominal pain, dyspepsia, weight loss, fever and malaise. ,,
Adenomyoma is considered a benign and slowly growing lesion. Few cases of adenomyomas have shown a rapid growth indicating that some such lesions may be neoplastic. Some authors consider adenomyoma a hamartomatous lesion. , Others consider adenomyoma as a focal diverticulum with muscular hypertrophy secondary to increased intraluminal pressure.  We feel that the simultaneous presence of choledochal cyst and adenomyoma in our case may favor the second hypothesis. The exact cause of development of choledochal cyst is uncertain. Anatomically abnormal choledochopancreatico ductal junction, acquired causes such as webs, strictures or dysfunction at the Sphincter of Oddi More Details or a genetic tendency to develop choledochal cyst are some of the theories put foreword to explain the genesis of choledochal cysts.  The underlying denominator in all these causes is increased intraluminal pressure in the bile duct leading to its dilatation and formation of choledochal cyst. Increased pressure in the choledochal cyst may form a diverticulum of bile duct mucosa into the duct wall and subsequent muscular hypertrophy leads to development of an adenomyoma. Cases of adenomyoma arising in the bile duct are known; however, adenomyoma occurring in a choledochal cyst has not been described previously, although choledochal cyst itself is a well-known entity. ,, In patients who develop adenomyoma of bile ducts without dilatation of biliary tract, the intraluminal pressure might just be enough to form a diverticulum of the mucosa into the duct wall to form an adenomyoma but may not be enough to dilate the biliary tract to form a choledochal cyst. If a diverticulum does not form at this stage, then as the bile duct dilates due to increased intraluminal pressure to form a choledochal cyst, the wall of the bile duct also gets thickened by inflammation and fibrosis, and then it becomes much more difficult to form a diverticulum through the thickened fibrotic duct wall to form an adenomyoma. This may be the reason that adenomyomas occurring in a bile duct have been seen but adenomyoma occurring in a choledochal cyst has not been reported. However, we also realize that the presence of adenomyoma and choledochal cyst together in our case may just be a coincidence.
Differential diagnosis of adenomyoma includes adenocarcinoma, adenomyomatous hyperplasia of gallbladder, adenoleiomyomatous hyperplasia of the intestine, ectopic pancreatic tissue, ectopic gastric mucosa, fibroadenoma and Brunner gland hyperplasia. Most adenocarcinomas of the CBD show malignant cells and intense desmoplastic reaction which is not present in an adenomyoma. ,,,
Importance of adenomyoma lies in its propensity to cause symptomatic biliary tract obstruction leading to suspicion of malignancy and extensive surgical resection. Preoperative diagnosis of extrahepatic biliary tract adenomyoma is difficult. Liver function tests, ultrasonography, computed tomographic scan, cholangiography, and endoscopy cannot distinguish this lesion from malignant lesions of the same site.  If the lesion is recognized intraoperatively, intraoperative frozen section examination may help in making a diagnosis of adenomyoma versus adenocarcinoma and planning surgery. However, in some cases, it may be difficult to arrive at the correct diagnosis even on frozen sections. , Postoperative histologic examination of surgical specimen is the only definite method for diagnosis.
A definitive surgical strategy for managing adenomyoma has not been established.  The most effective methods of treatment reported are endoscopic ampullectomy for ampullary tumors and local surgical resection for other sites. Radical surgery is not considered necessary. , In cases where the possibility of malignant tumor cannot be excluded, radical surgery (Whipple's pancreaticoduodenectomy) is performed. 
To conclude, adenomyoma is a rare lesion of the extrahepatic bile ducts and other sites. When adenomyoma is suspected, intraoperative frozen section examination is necessary to rule out malignant lesions to avoid radical excision. Complete excision of the lesion is adequate in majority of the cases unless a malignancy cannot be excluded, in which case, a radical surgery is necessary.
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Deepak Kumar Singh
597, Z-Type Flats, Lucknow Road, Timarpur, Delhi - 110 054
Source of Support: None, Conflict of Interest: None
[Figure 1], [Figure 2]