The lung-restricted marker napsin A is highly expressed in clear cell carcinomas of the ovary.
OBJECTIVE
We recently observed expression of the "lung" marker napsin A in ovarian clear cell carcinomas and therefore sought to determine the extent of napsin A expression in a subset of ovarian neoplasms.


METHODS
We identified an archival series of ovarian clear cell carcinomas (n = 36), serous borderline tumors (n = 21), high-grade serous carcinomas (n = 37), and endometrioid adenocarcinomas (n = 29). Using standard immunohistochemical techniques on whole sections of formalin-fixed, paraffin-embedded specimens, we employed a panel of antibodies: napsin A (IP64), estrogen receptor (SP1), WT-1 (6F-H2), PAX-8 (BC12), and TTF-1 (SPT24).


RESULTS
Thirty-six of 36 clear cell carcinomas showed napsin A expression, typically in a uniform pattern. None of the serous borderline tumors or high-grade serous carcinomas manifested napsin A expression. Napsin A was expressed in three (10%) of 29 endometrioid adenocarcinomas, generally in a focal pattern.


CONCLUSIONS
Our study showed that napsin A is an extremely sensitive (100%) marker of ovarian clear cell carcinomas and exhibits very high specificity (100%) in distinguishing clear cell carcinomas from high-grade serous carcinomas and serous borderline tumors and 90% specificity in discriminating clear cell carcinomas from endometrioid carcinomas.
From PhenoPath Laboratories, PLLC, Seattle, WA, and.
Patricia L
PL
Kandalaft
From PhenoPath Laboratories, PLLC, Seattle, WA, and.
Allen M
AM
Gown
CellNetix Pathology and Laboratories, Seattle, WA. cisacson@cellnetix.com.
Christina
C
Isacson
D018262:Adenocarcinoma, Clear Cell / Q000175:diagnosis* / Q000378:metabolism; D016282:Aspartic Acid Endopeptidases / Q000096:biosynthesis*; D014408:Biomarkers, Tumor / Q000032:analysis*; D018269:Carcinoma, Endometrioid / Q000175:diagnosis; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D010051:Ovarian Neoplasms / Q000175:diagnosis* / Q000378:metabolism; D012189:Retrospective Studies; D012680:Sensitivity and Specificity
D014408:Biomarkers, Tumor; D016282:Aspartic Acid Endopeptidases; C498549:NAPSA protein, human
Immunohistochemistry; Napsin A; Ovarian clear cell carcinoma