[1036] Inter-Observer Agreement among Pathologists for Assessing Invasion in Early Vulvar Squamous Cell Carcinoma: Still a Diagnostic Challenge

A Abdel-Mesih, D Daya, K Onuma, N Akhtar-Danesh, O Boutross-Tadross, K Ceballos, W Chapman, T Colgan, P Deb, MR Nucci, E Oliva, M Sur, S Tang, A Lytwyn. McMaster University, Hamilton, ON, Canada; University of British Columbia, Vancouver, BC, Canada; University of Toronto, Toronto, ON, Canada; Harvard University, Boston, MA

Background: Despite published criteria, measuring depth of invasion to identify early squamous cell carcinoma of the vulva remains difficult, yet critical for surgical management. Tumours with ≤1mm depth of invasion have minimal risk of nodal involvement, and therefore surgery is limited to local excision without lymphadenectomy. Interobserver agreement for determining the presence of invasion and its measurement has not been studied. Our aim was to assess agreement among pathologists for (1) determining whether invasion is present, and (2) measuring the depth of invasion.
Design: We searched the pathology database from 2000-2008, and identified 72 vulvar squamous cell carcinomas diagnosed as showing up to 5mm depth of invasion. From these, 45 slides were selected for this study, with preferential selection of challenging examples. Eleven gynecologic pathologists, from both Canadian and American institutions, independently reviewed the slides. Each slide was categorized as: (1) not invasive, (2) invasive with depth of invasion ≤1 mm, (3) invasive >1 mm, (4) invasive but depth cannot be measured, or (5) cannot determine if invasive or not invasive.
Results: There was only fair agreement (mean κ =0.24) among pathologists for diagnosing a vulvar carcinoma as being invasive. Of the 45 cases, only 13 (29%) were unanimously diagnosed by all 11 pathologists as being invasive. There was not a single case where all 11 pathologists agreed that there was no invasion. In 32 cases (71%), the pathologists did not unanimously agree on the presence or absence of invasion. Mean agreement for depth of invasion was only moderate (mean κ =0.50), and ranged from poor (κ= 0.12) to excellent (κ =0.92).
Conclusions: There was only fair agreement among gynecologic pathologists in determining the presence of invasion in vulvar carcinoma. In cases where pathologists agreed there was invasion, agreement on depth was only moderate. The fair to moderate agreement in this study may, in part, be due to the preferential selection of a larger proportion of diagnostically challenging cases. This study highlights that assessing whether or not there is invasion, and ascertaining the critical ≤ 1mm depth, still poses a diagnostic challenge for pathologists.
Category: Gynecologic & Obstetrics

Tuesday, March 23, 2010 1:00 PM

Poster Session IV # 135, Tuesday Afternoon


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