Immunohistochemical Profile of Endometrial Clear Cell Carcinoma
A Yemelyanova, R Vang, BM Ronnett. Johns Hopkins University, Baltimore, MD
Background: Clear cell carcinoma (CCC) of the endometrium is uncommon (∼5% of endometrial cancers), yet is not infrequently considered in the differential diagnosis of more common endometrioid and serous carcinomas when cells with clear cytoplasm or hobnail cells are present. These latter changes can reflect squamous and metaplastic-type differentiation in endometrioid carcinomas which are typically low-grade tumors, so identification of a true high-grade CCC component is important. The goal of this study is to characterize the immunoprofile of CCC for markers potentially useful to distinguish CCCs from other types of endometrial carcinomas.
Design: Immunohistochemical analysis of a panel of markers, including p53, p16, Pax8, HNF1B, WT-1, estrogen (ER) and progesterone receptors (PR), HSD3B1, and Ki-67 was performed on 20 cases of CCC (13 pure and 7 mixed tumors [3 with serous and 4 with endometrioid components]). For mixed tumors, expression was assessed in the CCC component. Percentage of positive cells was estimated (nearest 10%).
|Marker (# cases)||Number of negative cases||Number of positive cases||% positive cells (in positive cases)||Staining intensity|
|Pax8 (n=19)||1 (5%)||18 (95%)||84/100||40-100||Moderate to strong|
|HNF1B (n=18)||3 (17%)||15 (83%)||79/90||30-100||Moderate to strong|
|HSD3B1 (n=18)||3 (17%)||15 (83%)||79/90||30-100||Weak to strong|
|P16 (n=20)||1 (5%)||19 (95%)||52/40||10-100||Weak to strong|
|P53 (n=20)||6 (30%)||14 (70%)||60/70||10-100||Weak to strong|
|ER (n=20)||15 (75%)||5 (25%)||58/80||20-80||Weak to moderate|
|PR (n=20)||17 (85%)||3 (15%)||40/30||10-80||Moderate|
|WT-1 (n=19)||19 (100%)||0||-||-||-|