[444] Evidence That Judicious Use of a Cellient™ Cell Block and p16/Ki67 Immunohistochemistry (IHC) in Pap Tests Improves the Prediction of Biopsy Findings of CIN2 or Worse

Wei Xing, Andrew Fischer, April Y Hou, Zhong Jiang. University of Massachusetts Medical School, Worcester, MA; Brandeis University, Waltham, MA

Background: P16 and Ki67 stains are increasingly used in cervical biopsies. Little data is available for use of p16 and Ki67 stains in cell blocks of Pap tests.
Design: 56 Pap tests between January 2010 and March 2012 with equivocal diagnoses on Pap smear were examined with H&E stained Cellient™ cell blocks and p16 and/or Ki67 immunohistochemistry (IHC). Cellient utilizes a flow-through embedding technique and automatically positions cells at a defined plane in paraffin to maximize cell yield. The final pathologist diagnoses based on review of the cell block and IHC findings were compared to the cytotechnologist diagnoses based on the Pap test alone. The diagnoses based on the Pap test alone and IHC slides were confirmed in a subset of cases. Two-tailed chi square test was used for statistical analysis.
Results: The cytotechnologist Pap test diagnoses on the 56 cases are shown in Table 1.

Table 1. Cytotechnologists diagnoses on pap test vs. cell block with IHC.
CytotechnologistPathologist diagnoses integrating cell block with p16/Ki67 IHC
Pap smearSub-totalNILMASCUS/LSILLSIL-H/ASC-HAGCHSILMALIGNANT
Reactive1324331 
ASCUS/LSIL15254 31
LSIL-H/ASC-H2  2   
AGC18431622
HSIL8  4 4 
Total56812149103


Diagnoses were changed following pathologist review of cell blocks and IHC slides in 37 cases (66%) whereas diagnoses were unchanged in 19 cases. Of the 37 altered diagnoses, 23 were upgraded and 14 were downgraded. Twenty seven of the 37 cases have follow-up biopsies or Pap tests, of which cervical intraepithelial neoplasia 2 (CIN 2) or worse were confirmed in 39% (7/18) upgraded cases versus 0% (0/9) downgraded cases (P=0.03) (Table 2). On selected review of cases, IHC stains were essential for both upgrading and downgrading.

Table 2. Follow-up on upgraded and downgraded Pap tests.
 Diagnoses on follow up 
 >=CIN2Total
Upgraded11718
Downgraded909
Total20727
=CIN2: CIN2, CIN3, carcinoma in situ, adenocarcinoma.


Conclusions: Judicious addition of a Cellient cell block and p16/Ki67 IHC improves the prediction of biopsy findings of CIN2 or worse. Cell block and IHC may be cost-effective by obviating the need for colposcopy, or allowing patients to proceed directly to a diagnostic excisional procedure (e.g., LEEP) if a histologic diagnosis can be provided on the Pap test sample. A proposal for uniform criteria for scoring these immunostains on cell blocks of pap tests is presented.
Category: Cytopathology

Monday, March 4, 2013 1:00 PM

Poster Session II # 86, Monday Afternoon

 

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