Circulating Endometrial Cells in Women with Spontaneous Pneumothorax

Abstract Background The occurrence of catamenial pneumothorax (CP) is rare and the awareness of this diagnosis among clinicians is insufficient. CP is highly correlated with pelvic endometriosis and remains the most common form of thoracic endometriosis syndrome. Circulating Endometrial Cells (CECs) were previously detected in patients with pelvic endometriosis. Could CECs bring new insights into pneumothorax management? Methods The presented study aims to describe the occurrence and molecular characteristics of CECs in women with spontaneous pneumothorax (SP) (n= 20) with high suspicion of its catamenial character. CECs were enriched from peripheral blood by size-based separation (MetaCell®). In addition to cytomorphology, gene expression profiling of captured cells was performed for 24 endometriosis associated genes. Results CECs were present in all 20 patients with SP. Enriched CECs exhibited four character features: epithelial, stem -cell like, stroma-like, and glandular. However, not all of them were present in every sampling. Gene expression profiling revealed two distinct phenotypes of CECs in SP/CP, whereby one of them refers to the diaphragm openings syndrome and the second to the endometrial tissue pleural implantations. Comparisons of the gene expression profiles of CECs in pneumothorax (CECs-SP) with CECs in pelvic endometriosis (CECs-non-SP) have revealed significantly higher expression of HER2 in CECs-SP compared to CECs-non-SP. Conclusion This proof of concept study demonstrates successful isolation and characterization of CECs in patients with SP. Identification of CECs in SP could alert endometriosis involvement and help early referral to gynecologic consultation for further examination and treatment.