[1111] PAX8 Immunohistochemical (IHC) Expression in Endocervical Glandular Lesions

Richard Danialan, Margaret Assaad, Richard W Cartun, Srinivas Mandavilli. Hartford Hospital/Clinical Laboratory Partners, Hartford, CT

Background: Glandular lesions of the endocervix can be diagnostically challenging and occasionally the differential diagnosis includes both endocervical (ECA) and endometrial adenocarcinomas (EmCA). PAX8 expression has been recently described in the normal endocervix, but there is limited literature evaluating its expression in benign and malignant endocervical lesions, particularly in the context of currently utilized IHC markers such as p16, Ki-67 and CEA. We wanted to evaluate the potential utility of PAX8 to this IHC panel.
Design: We searched our pathology files for benign cervical lesions including: microglandular hyperplasia (MGH), endocervical laminar hyperplasia (ELH), tuboendometrioid metaplasia (TEM), cervical endometriosis (CEM), and tunnel clusters (TC). Premalignant and malignant cohort included: endocervical adenocarcinoma in situ (EC AIS), invasive endocervical adenocarcinoma (ECA), and mucinous/ MGH variants of endometrial adenocarcinoma (EmCA). An IHC panel of CEA, Ki-67, p16 and PAX8 was performed on all cases. Immunoreactivity was scored on degree of positivity (S0 – no staining, S1- up to 10% cells staining, S2- between 10-50% cells staining, S3- >50% cells staining) and intensity (I1-mild, I2-moderate, I3-strong).

Table 1
Diagnosis/# of casesCEAKi-67p16PAX8
TC (5)S0/I0S0/I0S1/I2S3/I2
CEM (4)S0/I0S1/I2S1/I3S3/I3
ELH (2)S0/I0S1/I1S1/I1S3/I2
MGH (4)S0/I0S0/I0S1/I2S2/I2
TEM (2)S0/I0S0/I0S1/I3S3/I2

Table 2
Diagnosis/# of casesCEAKi-67p16PAX8
ECA (3)S2/I3S3/I2S3/I2S1/I1
EC AIS (4)S2/I2S2/I2-3S3/I2S2/I1
EmCA (5)S0/I1S2/I2-3S3/I3S3/I1-2 (4)*
* 1 case of EmCA was negative for PAX8

Conclusions: 1. PAX8 shows diffuse positivity with at least moderate intensity in a spectrum of benign endocervical glandular lesions.
2. PAX8 intensity and extent of staining progressively decreased from benign lesions to EC AIS to ECA with ECA showing only focal/ rare staining with mild intensity. This alteration raises possible role of PAX8 in ECA.
3. Variants of EmCA (mucinous/ MGH) show diffuse PAX8 positivity with variable intensity.
4. PAX8 IHC could be added to a panel of other IHC markers in distinguishing benign endocervical lesions from ECA and extent of PAX8 staining could help in separation of ECA from EmCA.
Category: Gynecologic & Obstetrics

Tuesday, March 20, 2012 1:00 PM

Poster Session IV # 123, Tuesday Afternoon


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