An Analysis of the Revised CAP Protocol for Reporting Papillary Thyroid Carcinoma (PTC).
Mariah B McCready, Haresh Mani, Nicole Williams, Henry S Crist. PSHMC, Hershey, PA
Background: The CAP protocol for reporting thyroid tumors was revised in 2009. We analyzed the effect of these changes in PTC reporting by general surgical pathologists in a large academic center.
Design: All PTCs diagnosed from Jul 2009 to Jul 2010 were retrieved and information from CAP synoptic reports tabulated. Next, slides of tumors were coded for blinding and independently classified by 3 head-neck pathologists and 1 pathology fellow, followed by consensus review. Results were analyzed.
Results: Of 51 PTCs diagnosed by general surgical pathologists in the period under study, 18 were reported using the revised and 33 by the prior (2006) CAP protocol. Follicular variant PTC (FVPTC) had been overdiagnosed using the prior protocol (12/33) as compared to the revised protocol (3/18). On review, 3/12 (25%) in the former group, but none in the latter, were reclassified (2 classical, 1 solid). Of 17 microcarcinomas identified on review, only 2/9 were reported by the prior vs. 5/8 by the revised protocol. Thus the diagnosis of FVPTC and microcarcinoma was more precise with the revised protocol. Second tumors, when present, were mentioned in all reports. However 3/9 second tumors in the prior reports lacked a specific variant classification, while all second tumors in the later reports had been subclassified. The presence of lymphovascular invasion was specified in both the prior and revised synoptic reports. However prior to the revision, the presence or absence of extrathyroidal extension was not specifically reported.
All cases were reviewed independently and by consensus. All 3 head-neck pathologists agreed initially on subclassification in 76% of cases, 2 of 3 in 96% cases, and there was complete disagreement in 2% cases. The greatest agreement was with classical, followed by FVPTC and columnar cell variants. Interobserver variation was greatest in designation of tall cell and solid variants. Compared to consensus diagnosis, the pathology fellow had correctly subclassified 89% of cases, but had misclassified 2 cases of classical PTC as oncocytic and 2 FVPTC as classical.
Conclusions: The revised CAP synoptic report resulted in more precise diagnosis of FVPTC and microcarcinomas. Improved diagnosis of FVPTC may be due to the requirement of specifically evaluating architecture in the revised protocol. The revised protocol also resulted in specific documentation of second tumors and extrathyroidal extension. Diagnosis of variants other than follicular and classical PTC is difficult. Inclusion of well-defined criteria and definitions within the CAP protocol notes may be helpful for both general surgical and head-neck pathologists.
Tuesday, March 1, 2011 1:00 PM
Poster Session IV # 33, Tuesday Afternoon