Does Better Specimen Orientation and a Simplified Grading System Promote More Reliable Histologic Interpretation of Serrated Colon Polyps in the Community Practice Setting? Results of a Nationwide Study.
BACKGROUND
Colonoscopic surveillance guidelines for serrated polyps (SPs) are predicated upon the histologic characteristics of the index polyp. However, discrimination between SP subtypes [hyperplastic polyps vs. sessile serrated adenoma/polyps (SSA/P)] is often unreliable.


METHODS
We studied the impact of (1) a novel tissue orientation method, performed in the endoscopy laboratory, whereby polyps are flattened in a small paper envelope immediately after resection (modified protocol); and (2) 2012 consensus-modified criteria (CM-2012). These interventions were compared with conventional tissue-handling protocol (CP) and traditional 2008 World Health Organization criteria (WHO). Twenty blinded community pathologists from around the United States scored 100, independent, 0.5 to 2.0 cm, proximal colonic SPs randomly selected from a 2-site tissue section archive. We compared interobserver agreement and diagnostic grading.


RESULTS
Interobserver agreement was higher using CM-2012 than WHO criteria (absolute agreement: 13% vs. 4%, P<0.01; 75% agreement: 54% vs. 38%, P<0.01). Interobserver agreement was higher with the modified protocol than with CP (WHO absolute agreement: 6% vs. 2%, P>0.05; WHO 75% agreement: 46% vs. 30%, P>0.05, and CM-2012 absolute agreement: 20% vs. 6%, P=0.07; CM-2012 75% agreement: 66% vs. 42%, P=0.03). Compared with WHO, use of CM-2012 criteria resulted in fewer diagnoses of "indeterminate"; more diagnoses of SSA/P (P<0.01); and "upgraded" the diagnosis from hyperplastic polyps to SSA/P in approximately 7% of cases. These observations were independent of polyp size, patient gender, and study site.


CONCLUSIONS
Simple enhancements to postresection SP handling and diagnostic criteria markedly improve interobserver agreement of SP diagnosis among nongastrointestinal community pathologists. This finding, if confirmed, has important implications for SP colonoscopy surveillance guidelines.
*Department of Medicine, Icahn School of Medicine at Mount Sinai #Division of Gastroenterology ‡Department of Biostatistics, Columbia University §Department of Medicine, New York University School of Medicine ∥Icahn School of Medicine at Mount Sinai †Department of Medicine, Georgetown University Hospital, Washington, DC ¶Statistical Consultant, New Hope, PA Departments of **Medicine, Division of Gastroenterology ††Pathology, VA Palo Alto Health Care System, Stanford University School of Medicine, Palo Alto, CA.
Jennifer M
JM
Kolb
Shannon J
SJ
Morales
Nicholas A
NA
Rouse
Jay
J
Desai
Kathryn
K
Friedman
Lukas
L
Makris
Neville D
ND
Bamji
Kenneth M
KM
Miller
Roy M
RM
Soetikno
Tonya
T
Kaltenbach
Robert V
RV
Rouse
James
J
Aisenberg
D000236:Adenoma / Q000473:pathology*; D003110:Colonic Neoplasms / Q000473:pathology*; D003111:Colonic Polyps / Q000473:pathology*; D005260:Female; D006652:Histological Techniques / Q000379:methods* / Q000592:standards; D006801:Humans; D008297:Male; D015588:Observer Variation; D010338:Pathology, Clinical / Q000379:methods / Q000592:standards; D017410:Practice Guidelines as Topic; D011365:Professional Practice Location; D016037:Single-Blind Method; D013048:Specimen Handling / Q000379:methods* / Q000592:standards