Detection of In Situ and Invasive Endocervical Adenocarcinoma on ThinPrep Pap Test: Cytological-Histological Correlation in 78 Patients

Abstract

False negative (FN) or false unsatisfactory (F-Unsat) rates for adenocarcinoma in situ (AIS) and invasive endocervical adenocarcinoma (ECA) in conventional Pap smears is 50% (Krane et al. Cancer Cytopathol, 2001;93:8). Data on detection of AIS and ECA, on ThinPrep Pap test (TPPT) are scant. Patients with histologically proven AIS and ECA during a 16-year period (1998)(1999)(2000)(2001)(2002)(2003)(2004)(2005)(2006)(2007)(2008)(2009)(2010)(2011)(2012)(2013)(2014) were identified. The TPPT immediately preceding the histologic diagnosis of AIS or ECA was designated as Index Pap (IP). All available unsatisfactory and negative TPPTs were reviewed. There were 78 patients (mean age 38), histologic AIS, 56; ECA, 22, with 184 TPPT. Thirtysix (46%) patients had associated with HSIL. Histologic diagnosis of AIS and ECA was either concurrent or 22.5 months (mean) after IP. In 68/78 (87%) patients, IP was abnormal. Results of 89 of 184 TPPTs from 38 patients (AIS 30, ECA 8) were originally: unsatisfactory 1, negative 88. Of these 42 TPPT, one unsatisfactory and 41 negative, from 27 patients, were available for review. The remaining 47 negative TPPTs had been legally discarded. Upon review, 21 of 42 TPPTs were true negatives (sampling) and 21 of 42 TPPTs from 17 patients (AIS 13, ECA 4) were reclassified as unsatisfactory 1, FN 20. Endocervical cells (EC) were present in all cases. FN-AIS showed less feathering, smaller, rounder cells in tighter clusters and darker attenuated nuclei; FN-ECA showed cleaner background, less pronounced nucleoli and other features of FN-AIS. Neoplastic cells were mistaken for tubal metaplasia, reactive EC and benign endometrial cells. The one unsatisfactory case showed few cells obscured by blood. Based on slides reviewed, F-Unsat and FN rates were 17.4%. Sensitivity of TPPT for detection of AIS and ECA was 82.6% based on any abnormal TPPT. F-Unsat and false negative TPPTs for AIS and ECA can be attributed to issues relating to sampling, alteration of background and cellular criteria, and fewer diagnostic cells.