[1175] Transitional Cell-Like Growth in Ovarian Endometrioid Carcinoma: Clinicopathological, Immunohistochemical and Behavioral Features Distinguishing It from High Grade Serous Carcinoma

Anthony N Karnezis, Anil Aysal, Charles J Zaloudek, Joseph T Rabban. UCSF, San Francisco, CA

Background: The endometrioid subtype of ovarian cancer (OEC) is distinguished from high grade serous (OSC) by its genetics, clinical presentation, histologic precursors, immunophenotype, and behavior. Ribbon-like growth resembling transitional cell carcinoma (TCC) of the urinary bladder has been described in OSC, ovarian TCC (OTCC) and endometrioid endometrial carcinoma (EEC). The purpose of this study was to determine whether transitional cell-like morphology (TCLM) occurred in OEC and describe the clinical, histological and immunophenotypic characteristics that distinguish it from OSC and OTCC.
Design: All pure OECs from our institute between 1982 and 2009 were examined for TCLM: undulating ribbons or compact nests resembling OSC and OTCC. To exclude OSCs that were misdiagnosed as OEC, high grade tumors that expressed the WT1, a marker of OSC, in the transitional cell component were excluded. We examined the morphologic and immunohistochemical features specifically in the TCLM.
Results: Of 71 OECs examined, we identified 10 tumors (14%) that showed TCLM. The women were 39-79 years old (mean, 52 years). Five tumors were stage I, 2 stage II, and 3 stage III. The tumors ranged from 8.5 to 23 cm (mean, 15 cm). One tumor was FIGO grade 1, 3 grade 2 and 6 grade 3. The TCLM occupied 5% to 90% of the overall tumor (mean, 41%). Varying degrees of squamous differentiation were present in the TCLM in 9 tumors. None contained small papillae or benign Brenner tumor, and only one had rare psammoma bodies. Two were associated with endometriosis. Within the TCLM, WT1, p63, inhibin, calretinin and SF1 were negative in the all cases. ER was positive in 8 tumors. One grade 3 tumor was diffusely positive for p53, but this tumor was p16 negative. One tumor was negative for MLH1 and PMS2. Two patients (20%) with the transitional cell pattern died (average follow-up, 47 months), and 14 (23%) without the transitional cell pattern died (average follow-up, 41 months).
Conclusions: Some OECs show a transitional cell growth pattern that resembles OSC and OTCC, but this does not appear to affect behavior. Admixed squamous differentiation and absence of diffuse WT-1, p53 and p16 expression are the most useful features to prevent over-diagnosis of this pattern as OSC or OTCC.
Category: Gynecologic & Obstetrics

Wednesday, March 21, 2012 9:30 AM

Poster Session V # 157, Wednesday Morning


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