[965] Interobserver Reproducibility (IOR) in the Diagnosis of Invasive Micropapillary Carcinoma (MPC) of the Genitourinary Tract among Expert Urologic Pathologists

AR Sangoi, AH Beck, MB Amin, L Cheng, JI Epstein, DE Hansel, KA Iczkowski, JY Ro, A Lopez-Beltran, E Oliva, GP Paner, VE Reuter, RB Shah, SS Shen, P Tamboli, JK McKenney. Stanford, Stanford, CA; Cedars-Sinai, Los Angeles, CA; U Indiana, Indianapolis, IN; Johns Hopkins, Baltimore, MD; Cleveland Clinic, Cleveland, OH; U Colorado, Aurora, CO; Methodist, Houston, TX; Unit Anatomic Pathology, Cordoba, Spain; Massachusetts General Hospital, Boston, MA; Northwestern, Chicago, IL; Memorial Sloan Kettering, New York, NY; U Michigan, Ann Arbor, MI; UT MD Anderson, Houston, TX

Background: IOR for the diagnosis of MPC has not been studied, despite the reported clinical relevance.
Design: Digital images from 30 urothelial carcinomas (UC) were given to 14 GU subspecialists with request to indicate cases qualifying as MPC. The 30 pre-selected cases included both (presumably) classic MPC (n=10) and UC with retraction and variably sized nests (non-classic/potential MPC)(n=20). IOR was evaluated by kappa analysis. To assess putative criteria applicable in difficult cases, tumor nest size, nest anastomosis, extensive retraction, multiple nests in same lacunar space, peripheral nuclei, rings, elongate processes, and columnar cells were recorded.
Results: Moderate agreement (kappa:0.54) was reached for the 30 cases. Cases diagnosed as MPC ranged from 9/30 to 20/30 (median:13/30). Of the 10 proposed classic MPC, all pathologists classified at least 8/10 as MPC [sensitivity of 130/140 (93%)]. Of the 20 other cases, MPC diagnoses varied with 6 pathologists classifying no more than 2/20 as MPC; 5 classifying between 4-7/20 as MPC; and 3 classifying from 9-11/20 as MPC. Cluster analysis revealed a distinct group of 6 pathologists with high diagnostic agreement (kappa:0.79) and high sensitivity (0.95) and specificity (0.95) for classic MPC. Multiple nests within the same lacunar space had the most significant association with an MPC diagnosed by this group.
Conclusions: Pathologists demonstrate high levels of sensitivity for identifying classic MPCs, but there is considerable variability in the diagnosis of other UC with retraction. Evaluation of features that potentially correlate with aggressive behavior is warranted to refine diagnostic criteria for MPC.
Category: Genitourinary (including renal tumors)

Tuesday, March 23, 2010 1:00 PM

Poster Session IV # 97, Tuesday Afternoon

 

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