Napsin A is a specific marker for ovarian clear cell adenocarcinoma

Abstract

Ovarian clear cell adenocarcinoma has a relatively poor prognosis among the ovarian cancer subtypes because of its high chemoresistance. Differential diagnosis of clear cell adenocarcinoma from other ovarian surface epithelial tumors is important for its treatment. Napsin A is a known diagnostic marker for lung adenocarcinoma, and expression of napsin A is reported in a certain portion of thyroid and renal carcinomas. However, napsin A expression in ovarian surface epithelial tumors has not previously been examined. In this study, immunohistochemical analysis revealed that in 71 of 86 ovarian clear cell adenocarcinoma patients (83%) and all of the 13 patients with ovarian clear cell adenofibroma, positive napsin A staining was evident. No expression was observed in 30 serous adenocarcinomas, 11 serous adenomas or borderline tumors, 19 endometrioid adenocarcinomas, 22 mucinous adenomas or borderline tumors, 10 mucinous adenocarcinomas, or 3 yolk sac tumors of the ovary. Furthermore, expression of napsin A was not observed in the normal surface epithelium of the ovary, epithelia of the fallopian tubes, squamous epithelium, endocervical epithelium, or the endometrium of the uterus. Therefore, we propose that napsin A is another sensitive and specific marker for distinguishing ovarian clear cell tumors (especially adenocarcinomas) from other ovarian tumors.

Data set for reporting of ovary, fallopian tube and primary peritoneal carcinoma: recommendations from the International Collaboration on Cancer Reporting (ICCR)

“…130 Napsin A is also a useful marker of clear cell carcinomas. 131 ER is positive in most high-grade and low-grade serous carcinomas and endometrioid carcinomas while clear cell carcinomas are usually negative. Some of these markers have helped establish that most neoplasms, which were previously classified as mixed high-grade serous and endometrioid and mixed high-grade serous and clear cell, represent HGSCs with pseudoendometrioid areas and areas of cytoplasmic clearing.…”

Napsin A is frequently expressed in clear cell carcinoma of the ovary and endometrium

“…Recent studies have reported napsin A expression in a subset of ovarian clear cell carcinomas (O-CCCs, 69%-100%) as well as in up to 10% of ovarian and 6%-10% of endometrial (EM) endometrioid carcinomas (EC); in contrast, it is rarely found in high-grade serous carcinoma (HGSC) [7,[9][10][11][12][13]. Napsin A expression in EM-CCC has been observed in 67%-93% of the cases [11,[14][15][16][17].…”

Ovarian Cancer: A Heterogeneous Disease

“…In contrast to SC, CCC do not usually express WT1, p53, and ER. They specifically express napsin A, in contrast to the other EOC [50]. Some studies have shown that the tumor suppressor ARID1A is mutated in almost half of CCC cases [39,51].…”