A Unique Case of Gallbladder Cancer Arising in the Neck Side of Segmental Adenomyomatosis That Mimicked Hepatocellular Carcinoma on Contrast CT

Case Report OGH Reports

A unique case of gallbladder cancer arising in the neck side of segmental adenomyomatosis that mimicked hepatocellular carcinoma on contrast CT

Keita Kai,1 Takao Ide,2 Ryoko Egashira,3 Yasuo Koga,2 Kota Wakiyama,2 Kenji Kitahara,2 Hiroyuki Irie,3 Hirokazu Noshiro,2 Osamu Tokunaga1 1Department of Pathology & Microbiology, Saga University Faculty of Medicine, Saga, Japan 2Department of Surgery, Saga University Faculty of Medicine, Saga, Japan 3Department of Radiology, Saga University Faculty of Medicine, Saga, Japan

ABSTRACT

A 53-year-old Japanese female was admitted to our hospital for examination and treatment of an abdominal mass lesion. Contrast-enhanced abdominal computed tomography (CT) showed a well-circumscribed mass that measured approximately 5 cm. Although the tumor was located near the neck of the gallbladder, it seemed to be pedunculated from the liver parenchyma. From the enhancement pattern and morphological characteristics of the contrast CT images, the nodule was preoperatively diagnosed as hepatocellular carcinoma. The patient underwent a laparotomy, and it was intraoperatively revealed that the tumor existed solely in the neck of the gallbladder without serosal invasion. Whole-layer cholecystectomy with lymph node dissection was therefore performed. A pathological examination revealed that the papillary tumor filled up the neck side lumen of the segmental type of adenomyomatosis (ADM). The tumor was histologically diagnosed as papillary adenocarcinoma. Cases of papillary adenocarcinoma arising on the neck side lumen of the segmental type of ADM are extremely rare. Furthermore, no such case of gallbladder cancer which mimicked hepatocellular carcinoma has previously been reported.

Keywords: Gallbladder cancer, adenomyomatosis, papillary adenocarcinoma, hepatocellular carcinoma.

INTRODUCTION of ADM forms an annular stricture comprising a thickened wall dividing the gallbladder lumen into separate intercon- Adenomyomatosis (ADM) of the gallbladder is defined nected compartments, with or without diffuse wall thick- as an epithelial proliferation and hypertrophy of the mus- ening on the fundal side. Several reports have described cularis with outpouching of the mucosa into or through that gallbladder cancer was sometimes found in the fundal the thickened muscular layer, forming the so-called side of the segmental type of ADM.[3,4,5] but cancer aris- Rokitansky–Aschoff sinuses (RAS). Adenomyomatosis is ing on the neck side of the segmental type of ADM is categorized by its gross features as the diffuse type, fundal extremely rare. We recently encountered a unique case of (localized) type or segmental type.[1 –3] The segmental type gallbladder cancer arising in the neck side of segmental ADM. Further, this case showed unusual morphology and *Corresponding address: Keita Kai Department of Pathology & Microbiology, mimicked hepatocellular carcinoma in an imaging study. Faculty of Medicine, Saga University Nabesima 5-1-1, Saga City, Saga 849-8501, Japan Tel: +81-952-34-2234; Fax: +81-952-34-2055 CLINICAL SUMMARY Email: [email protected] A 53-year-old Japanese female suffered from right hypo- DOI: 10.5530/ogh.2012.1.7 chondrial pain and was admitted to a local hospital under

Oncol. Gastroenterol. Hepatol. Reports Vol.1 / Issue 1 / Jul–Dec, 2012 33 Keita Kai, et al.: A unique case of gallbladder cancer arising in the neck side of segmental adenomyomatosis the diagnosis of acute cholecystitis. She underwent treatment for acute cholecystitis, and the presence of gallstones and an abdominal mass lesion were found by an imaging study. The patient was subsequently admitted to our hospital for further examination and treatment of the abdominal mass lesion. Laboratory tests performed on admission revealed no abnormality in the patient’s red blood cell count (4.78 ×106/μl), hemoglobin concentra- tion (12.2 g/dl), white blood cell counts (7600/μl) or platelet count (28.1 ×104 /μl). Serology and coagulation tests also showed no abnormalities. All of the examined tumor markers were within normal ranges, including those for carcinoembryonic antigen (CEA), carbohydrate antigen (CA)19-9, Dupan-2 antigen, SPan-1 antigen, protein induced by vitamin K absence (PIVKA)-II and alpha-fetoprotein (AFP). Figure 2. The sagittal view of the contrast abdominal CT. Although the tumor was located near the neck of the gallblad- Contrast-enhanced abdominal computed tomography der, it seemed to be pedunculated from the liver parenchyma (CT) showed a well-circumscribed mass that measured (arrow). approximately 5 cm. The tumor showed mild enhancement in the early phase, and this enhancement was was performed. Intraoperatively, the tumor was found to washed out in delayed phase (Fig. 1). Although the tumor be located at the neck of the gallbladder, and no sero- was located near the neck of the gallbladder, it seemed sal invasion or adhesion to other organs was observed. to be pedunculated from the liver parenchyma of seg- Whole-layer cholecystectomy was performed. The his- ment 6 (Fig. 2). The structures of the neck of the gall- tology of the papillary adenocarcinoma and the surgical bladder and the cystic duct were unclear in the images. margin of the cystic duct were intraoperatively con- After discussion of whether the tumor originated from firmed by a frozen section analysis. After the histological the liver parenchyma or the neck of the gallbladder, a examination of frozen sections, lymph node dissection preoperative diagnosis of hepatocellular carcinoma at was additionally performed, and the operation was com- segment 6 of the liver was made. Under the presumed pleted. The patient’s postoperative course was unevent- diagnosis of hepatocellular carcinoma, surgical resection ful, and she was discharged from the hospital two weeks after the operation.

PATHOLOGICAL FINDINGS

A grossly papillary tumor filled up the neck side lumen of the segmental type of ADM (Fig. 3). The fundal side lumen contained white gall and a lot of gallstones. His- tologically, atypical tumor cells proliferated as tubular structures in part, but dominantly showed a papillary structure, and were therefore diagnosed as papillary adenocarcinoma (Fig. 4a). The tumor invaded into the subserosal layer, but no serosal invasion was observed. A lot of dilated RAS were observed at the annular stricture (Fig. 4b). No cancer metastasis was observed in the (a) (b) examined lymph nodes.

Figure 1. a) The early phase of the contrast abdominal CT. A well-circumscribed mass (arrow) showed heterogeneous DISCUSSION enhancement by contrast medium. b) The delayed phase of the contrast abdominal CT. The enhancement of the nodule was Adenomyomatosis of the gallbladder has not been washed out in this phase (arrow). considered to have malignant potential. However, there

34 Oncol. Gastroenterol. Hepatol. Reports Vol.1 / Issue 1 / Jul–Dec, 2012 Keita Kai, et al.: A unique case of gallbladder cancer arising in the neck side of segmental adenomyomatosis adenocarcinoma was noted in our previous series of gallbladder cancer with ADM. Therefore, the present case where the papillary adenocarcinoma has arisen on the neck side of the segmental type of ADM is considered to be extremely rare.

Another interesting feature of present case is that the tumor mimicked hepatocellular carcinoma in the contrast CT images. Usually, it is easy to distinguish gallbladder cancer from hepatocellular carcinoma during imaging studies. We believe that there were several characteristics of the tumor and accidental factors that led to the unusual appearance of the nodule. First, the tumor filled up the cavity of the neck side of the segmental type of ADM and was demonstrated as a solid tumor in the CT Figure 3. The gross appearance of the resected gallbladder. images. Second, the lumen of the fundal side was mark- The papillary tumor filled up the neck side lumen of the seg- edly dilated, and made it look as if the lumen was the mental type of adenomyomatosis. entire lumen of the gallbladder. Third, the tumor existed very close to the liver parenchyma, and it looked as if the tumor was pedunculated from the liver parenchyma. Fourth, the enhancement pattern of the contrast CT images was consistent with the pattern of HCC rather than gallbladder cancer. The usual enhancement pattern of invasive gallbladder cancer is a gradual enhancement reflecting the stromal component of the tumor. Usu- ally, papillary adenocarcinoma contains a small amount of stroma, and the stroma of papillary adenocarcinoma contains a lot of blood vessels compared to other histological types of adenocarcinoma. These histological characteristics probably led to the early enhancement on contrast CT. (a) (b) In summary, we have herein presented a unique case of Figure 4. The histopathological features. a) The papillary gallbladder cancer arising in the neck side of a segmen- adenocarcinoma (hematoxylin and eosin, × 100). b) A lot of tal adenomyomatosis that mimicked hepatocellular carci- dilated Rokitansky–Aschoff sinuses were observed at the an- noma on contrast CT. Although this is a very rare case, nular stricture of the resected gallbladder (hematoxylin and and was modified by several unusual conditions, we have eosin, × 40). reported this case as a reference for similar cases that might be encountered in the future. have been several reports suggesting that gallblad- [6–10] der cancer may originate from adenomyomatosis REFERENCES or indicating that patients with the segmental type of adenomyomatosis have an increased risk of develop- 1. Jutras JA, Longtin JM, Levesque HP. Hyperplastic cholecystoses. ing gallbladder cancer.[3,4] Most of these reported cases AJR.1960;83:795–827. 2. Jutras JA, Levesque HP. Adenomyoma and adenomyomatosis of the were of gallbladder cancer that arose on the fundal gallbladder. Radiol Clin North Am. 1966;4:483–500. side of the segmental type of ADM. We have previ- 3. Ootani T, Shirai Y, Tsukada K, Muto T. Relationship between gallbladder carcinoma and the segmental type of adenomyomatosis of the gallbladder. ously analyzed 97 cases of surgically resected gallblad- Cancer. 1992 Jun 1;69(11):2647–52. der cancer and reported that 25 (25.8%) out of 97 4. Nabatame N, Shirai Y, Nishimura A, Yokoyama N, Wakai T, Hatakeyama K. [5] High risk of gallbladder carcinoma in elderly patients with segmental cases were grossly accompanied with ADM. In our adenomyomatosis of the gallbladder. J Exp Clin Cancer Res. 2004 previous series, there were only two cases where the Dec;23(4):593–8. 5. Kai K, Ide T, Masuda M, Kitahara K, Miyoshi A, Miyazaki K, et al. gallbladder cancer had arisen on the neck side of the Clinicopathologic features of advanced gallbladder cancer associated with segmental type of ADM. Furthermore, no papillary adenomyomatosis. Virchows Arch. 2011 Dec;459(6):573–80.

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