[1731] Mucinous Cystic Neoplasms of the Gallbladder: A Clinicopathological and Immunohistochemical Study

Juan C Hernandez Prera, Jie Ouyang, Stephen Ward, Xuchen Zhang, Hongfa Zhu, Swan N Thung, M Isabel Fiel. The Mount Sinai Medical Center, New York, NY

Background: Mucinous cystic neoplasms (MCN) of the hepatobiliary tree are rare tumors, but even rarer are MCN arising from the gallbladder (GB). Most are lined by a single layer of either gastric or pancreatobiliary epithelium with ovarian-type stroma. This study aims to characterize the clinical, histological and immunohistochemical (IHC) profile of GB MCN and compare them with intrahepatic (IH) MCN.
Design: The pathology database from 1995-2011 was searched; clinical data was gathered from medical records. Histological assessment was performed; IHC using antibodies to CK7, CK19, MUC2, MUC5AC and MUC6 was performed. Immunoreactivity was scored: 0 negative; 1 focal; 2 <50% cells + staining; 3 >50% strong + staining. Clinicopathological features and mucin profile were compared with 12 previously studied IH MCN.
Results: Six GB MCN of 16,638 GB specimens were found (0.03%). Four of 6 were female, mean age 72 years (range 55-90). All were incidentally found during unrelated surgical procedures (3 resection for malignant hepatic tumors, 2 colectomy, 1 harvesting for cadaveric donation). Five of 6 (83%) were located in the fundus; 1 in the GB neck; 4/6 (67%) were of the multilocular type, and 2 with combined multilocular and papillary architecture. Size ranged from 0.9-5cm (ave 1.8cm). Pure pancreatobiliary lining epithelium was found in 4/6 and mixed gastric and pancreatobiliary in 2/6; ovarian type stroma was seen in all cases. No epithelial dysplasia or carcinoma was found. The pancreatobiliary-type epithelium had 3+ staining for CK7, CK19 and MUC6; MUC2 was 1+ in 3 (50%). All cases were reactive to MUC5AC but with variable staining (1+ in 4, 3+ in 2). The gastric foveolar epithelium in the two mixed cases was 3+ for MUC5AC and MUC6, and 1+ for MUC2. Table 1 compares GB and IH MCN at our institution.

Table 1

	GB MCN	IH MCN
M:F	1:2	1:11
Age	72yrs(55-90)	45yrs(33-62)
Size	1.8cm(0.9-5)	8cm(1-29)
Epithelium	67% pancreatobiliary 33% mixed	33% pancreatobiliary 59% mixed 8% gastric
Ovarian stroma	100%	100%
MUC2	50%	8%
MUC5AC	100%	50%
MUC6	100%	42%

Conclusions: GB MCN are very rare tumors. Similar to IH MCN, they occur mostly in females. GB MCN, however are found in older patients. Lesions are smaller and are often incidentally found. Pure pancreatobiliary epithelium is the main lining in most cases whereas IH MCN are mainly mixed gastric and pancreatobiliary. GB MCN display a strong pancreatobiliary IHC phenotype as displayed by their reactivity for CK7 and CK19. The mucin expression of the tumor differs from IH MCN, suggesting that the phenotype of the cells is different from those of the liver.
Category: Liver

Monday, March 19, 2012 9:30 AM

Poster Session I Stowell-Orbison/Surgical Pathology/Autopsy Awards Poster Session # 263, Monday Morning