[961] The Morphologic Spectrum of Immunohistochemically Characterized Clear Cell Carcinoma of the Ovary: A Study of 83 Cases

D DeLair, R Soslow, B Gilks, A Macias, E Oliva. Memorial Sloan Kettering Cancer Center, New York, NY; Massachussets General Hospital, Boston, MA; Vancouver General Hospital, Vancouver, BC, Canada

Background: Establishing a diagnosis of ovarian clear cell carcinoma (OCC) can be subject to significant interobserver variation. Accurately diagnosing this tumor is important because of its chemoresistance and reported association with hereditary nonpolyposis colon cancer (HNPCC). The spectrum of morphologic features of OCC has not been well described in a series composed of immunohistochemically characterized cases.
Design: Eighty-three cases were retrieved from the files of two institutions in order to analyze the architectural and cytological features of OCC. The cases were previously studied with immunohistochemistry; approximately 80% were positive for HNF-1beta, and negative for p53, ER, PR, and WT1. A comprehensive list of architectural and cytologic features was analyzed including, but not limited to, nuclear pleomorphism (>3x variation in size), cytoplasmic characteristics, background changes, and mitotic rate (mitoses per 10 HPF). Between 1 and 13 slides were available for review for each case.
Results: Background changes included endometriosis (19/83, 23%), adenofibroma (19/83, 23%), or neither (37/83, 54%). OCCs most commonly demonstrated a mixture of architectural patterns including papillary, tubulocystic, and solid (29/83, 35%). A papillary component was present at least focally in the majority of the cases (62/83, 75%). The papillary patterns included non-hierarchical branching (59/62, 95%), the presence of small and round papillae (57/62, 92%), and detached micropapillary clusters (22/62, 35%), but rarely stratification of more than 3 cells thick. Nuclear pleomorphism and macronucleoli, if present, were only rarely diffuse (7/83, 8%). Clear cytoplasm was frequently found at least focally (78/83, 94%) as was hobnailing (63/83, 76%). The mitotic rate ranged from 0-10 with an average of 2-3. Other features often identified in OCCs included hyaline globules (33%), targetoid cells (18%), psammoma bodies (18%), a lymphoplasmacytic infiltrate (17%), and nuclear pseudoinclusions (12%).
Conclusions: Most OCCs have at least a focal papillary component. Recognizing the shape of the non-hierarchically branched papillae, lack of epithelial stratification, coupled with frequent yet only focal nuclear pleomorphism and a low mitotic rate should enable reproducible separation from entities in the differential diagnosis.
Category: Gynecologic

Monday, March 9, 2009 1:45 PM

Platform Session: Section C, Monday Afternoon