Differential Expression of CD24 and its Significance in Normal Endometrium, Hyperplastic Lesions and Endometrial Carcinoma

Abstract
Background: Endometrial carcinoma is considered the sixth most common cancer in women worldwide comprising 4% of all cancers in women. CD24 protein was originally reported to be expressed by pre-B lymphocytes. This protein had been recognized only as a cell marker for hematopoietic cell lineages. CD24 expression is considered as an important biomarker for diagnosis, disease progression and cancer-related death in many solid tumors, like breast, colonic and ovarian carcinomas.
Aim: The present work was conducted to study the immu-nohistochemical expression of CD24 in normal cyclic en-dometrium, hyperplastic endometrium and endometrial carci-noma, in order to demonstrate its expression pattern and to examine its association with various clinicopathological variables in endometrial carcinoma cases.
Material and Methods: The present study comprised 110 cases of endometrial tissue: 20 cases (18.2%) of cyclic en-dometrium, 30 cases (27.3%) of endometrial hyperplasia without atypia, 25 cases (22.7%) of atypical endometrial hyperplasia and 35 cases (31.8%) of endometrioid carcinoma. Immunohistochemistry was performed using the avidin biotin-peroxidase complex method.
Results: CD24 immunostaining was membranous and cytoplasmic. In the normal cyclic endometrium, membranous CD24 showed down-regulation in the proliferative phase and up-regulation in the secretory phase. Both membranous and cytoplasmic CD24 expression was statistically increase in endometrial carcinoma and reduced in hyperplastic lesion p<0.001 and p=0.004 respectivebly. Among cases of carcinoma, membrnuos CD24 expression was statistically significant with grade, stage and myometrial invasion (p=0.040 & p=0.044 and p=0.036 respectively). Cytoplasmic expression showed significant association with grade only (p=0.037). Membranous CD24 had 71.4% sensitivity and 76% specificity for differen-tiation of endometrioid carcinoma from atypical EH. Cyto-plasmic CD24 had low sensitivity (40%) but high specificity (80%) for distinction of endometrioid carcinoma from atypical endometrial hyperplasia. Total CD24 had 77.2% sensitivity and 76% specificity for distinction of atypical endometrial hyperplasia from endometrioid carcinoma.|Conclusion: Membernous CD24 was expressed in a cyclic pattern in the normal endometrium. CD24 expression was increased in case of endometrial carcinoma than hyperplastic lesion. These results suggest that CD24 can be a useful as diagnostic marker in differentiation between endometrial hyperplasia and carcinoma. Also CD24 implicated in progres-sion of endometrial carcinoma. Total CD24 expression (mem-bernous and cytoplasmic) is more specific and more sensitive in differentiation of atypical endometrial hyperplasia from endometrioid carcinoma.