[1172] Immunohistochemical Profile of Gastric Type Endocervical Adenocarcinoma, Including HER2/Neu Status

Yevgeniy Karamurzin, Vinita Parkash, Takako Kiyokawa, Robert A Soslow, Kay J Park. Memorial Sloan-Kettering Cancer Center, New York, NY; Yale University School of Medicine, New Haven, CT; Chiba University School of Medicine, Chiba, Japan

Background: Gastric type (GA) and minimal deviation adenocarcinoma (MDA) are subtypes of endocervical adenocarcinoma not related to infection by human papillomavirus (HPV) and are characterized by expression of gastric pyloric gland type mucin as evinced by HIK1083 immunoreactivity. The extent to which these tumors express other Mullerian or gastrointestinal (GI) immunophenotype has not been previously studied. We evaluated a series of GA/MDA for expression of such markers. Since gastric and ovarian mucinous carcinomas have been shown to overexpress HER2/neu with concurrent amplification (and are therefore amenable to targeted therapy with traztuzumab), we also included this stain in our panel.
Design: A retrospective review of GA or MDA from the pathology databases of two institutions was performed. Using standard protocols, immunohistochemical (IHC) studies were performed on formalin-fixed, paraffin embedded tissue for CK7, p16, CK20, CDX2, p53, PAX8 and Her2/neu. Her2/neu expression was scored according to the ASCO/CAP guidelines (0 to 3+). All others were scored semiquantitatively as POS (>50%), NEG (0), FOC (any to 50%).
Results: 16 cases with blocks available for staining were identified. Results are summarized in Tables 1 and 2. Four cases also had tissue from metastatic sites available for staining.

Table 1

	POS (%)	FOC (%)	NEG (%)
CK7	16 (100)	0	0
CK20	3 (19)	2 (13)	11(69)
p16	0	1 (6)	15 (94)
CDX2	0	4 (19)	12 (81)
p53	3 (19)	13 (81)	0
PAX8	7 (47)	3 (20)	5 (33)

POS >50% staining; NEG no staining; FOC <=50% staining

Table 2

	3+ (%)	2+ (%)	0/1+ (%)
Her2/neu	1 (6)	1 (6)	14 (82)

The metastatic tumors had similar staining patterns to the primary, except for 3 cases where CK20/CDX2 was either lost or focally gained. One case also lost PAX8 in the metastasis.
Conclusions: Gastric type and minimal deviation adenocarcinoma are characteristically CK7 and many, but not all, are PAX8 positive as well. p16 is negative, further supporting HPV-independent tumorigenesis. A minority of tumors express focal "GI markers" CK20 and CDX2 but are usually negative. p53 is overexpressed in 19% of these tumors which may indicate presence of TP53 mutation. Her2/neu shows 2+ or greater expression in 12% of cases which may be indicative of Her2 amplification.
Category: Gynecologic & Obstetrics

Tuesday, March 20, 2012 9:30 AM

Poster Session III # 170, Tuesday Morning