[1687] Tubulocystic Carcinoma of Bile Ducts: A Hitherto Unrecognized and Diagnostically Challenging Entity Often Mistaken as a Benign Lesion; Clinicopathologic Analysis of 6 Cases

Kee-Taek Jang, Burcu Saka, Yoh Zen, Stefan Pambuccian, Carlos Bacchi, Volkan Adsay. SMC, Seoul, Korea; Emory University, Atlanta, GA; KCH, London, United Kingdom; UM, Minneapolis, MN; CP, Botucatu, Brazil

Background: A previously unrecognized type of biliary adenoca characterized morphologically by a distinctive tubulocystic (TC) pattern highly similar to TC carcinoma of kidney is described.
Design: 6 examples of this entity were analyzed.
Results: M/F: 3/3; Mean age, 66 (44-78). Mean size, 4.4 cm (3-7). 3 intrahepatic, 3 perihilar. Microscopically, the tumors were virtually identical to the TC ca of the kidney, composed of a conglomerate of variably-sized cysts forming microcystic pattern (most within millimeters, some up to a centimeter) forming a relatively circumscribed mass with smooth bulging contours and “bubble wrap” appearance. The cysts contained homogenous secretory material, and were mostly lined by a single layer of relatively monotonous but atypical cuboidal to flat/attenuated cells without any overt mucin. The apical cytoplasm often contained projections resembling cilia or snouts, with focal hobnail pattern. Nucleoli were prominent in non-attenuated areas. In some tubules/cysts, daughter nodules composed of small round microtubules or abortive papillary units were noted, and in 2, there was transition into a florid papillary nodules. Nodular clusters of small tubules with cribriforming were also seen. Intervening stroma showed a distinctive nodular hyalinization with vascularity reminiscent of sclerosed hemangioma, and had chunky calcifications. None had ovarian type stroma.

One patient had perineural invasion by cystic units showing identical, bland cytology. In follow up, 1 was dead of disease at 9 mos; others, alive with no evidence of disease at 3,19, 19, 28, 58 mos.
Conclusions: A hitherto unrecognized biliary tumor type characterized by a distinctive TC pattern strikingly similar to the same named entity in the kidney is described. While the compact growth and relatively bland features may raise the impression of an unusual form of “in situ” carcinoma, other characteristics including perineural invasion confirm that, as in its renal kindred, this tumor type represents a peculiar, indolent form of invasive ca that defies the more conventional definition of “invasiveness” employed in the biliary/GI tract.
Category: Liver

Tuesday, March 5, 2013 9:30 AM

Poster Session III # 199, Tuesday Morning


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