Immunohistochemical expression of YKL-40 in peritoneal endometriosis

Abstract

Aims. To evaluate the relationship between the immunohistochemical expression of YKL-40 and peritoneal endometriosis by using paraffinized peritoneal tissue blocks.

Methods and materials. We retrospectively collected data from 27 patients whose pathologic reports indicated invasion of the peritoneum by endometriosis. A conventional peroxidase staining technique was performed using rabbit polyclonal antibody (Quidel® corporation, Santa Clara, CA) on peritoneal tissue blocks; their histology was then reviewed by a pathologist, and data were analyzed by nonparametric and Mann–Whitney tests.

Results. YKL-40 was detected immunohistochemically in 17 (63%) of 27 cases. The number of biopsies which were invaded by endometriosis (P = 0.015), with a score based on the revised classification of endometriosis (American Society for Reproductive Medicine) had statistical significance (P = 0.001). The obstetric history, age, body mass index, severity, and occurrence of dysmenorrhea, menstrual phase, preoperative CA 125, erythrocyte sedimentation rate, and white blood cell count had no statistical significance. YKL-40 immunoreactivity was recognized as brown staining, localized to the cytoplasm of epithelial cells of endometrial gland in peritoneal endometriosis. There was no positive staining on endometrial stromal cells or smooth muscle cells.

Conclusions. YKL-40 is related to severity of peritoneal endometriosis. However why a different expression level of immunohistochemical staining should occur is not known and needs further investigation.

Keywords:

• YKL-40
• endometriosis
• peritoneum

Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.