The Importance of Stromal Endometriosis in Thoracic Endometriosis

Abstract

Thoracic endometriosis (TE) is a rare type of endometriosis, where endometrial tissue is found in or around the lungs and is frequent among extra-pelvic endometriosis patients. Catamenial pneumothorax (CP) is the most common form of TE and is characterized by recurrent lung collapses around menstruation. In addition to histology, immunohistochemical evaluation of endometrial implants is used more frequently. In this review, we compared immunohistochemical (CPE) with histological (CPH) characterizations of TE/CP and reevaluated arguments in favor of the implantation theory of Sampson. A summary since the first immunohistochemical description in 1998 until 2019 is provided. The emphasis was on classification of endometrial implants into glands, stroma, and both together. The most remarkable finding is the very high percentage of stromal endometriosis of 52.7% (CPE) compared to 10.2% (CPH). Chest pain, dyspnea, right-sided preference, and diaphragmatic endometrial implants showed the highest percentages in both groups. No significant association was found between the recurrence rate and the various appearances of endometriosis. Sometimes in CPE (6.8%) and CPH (30.6%) no endometrial implants were identified underlining the importance of sensitive detection of endometriosis during and after surgery. We suggest that immunohistochemical evaluation should become mandatory and will improve diagnosis and classification of the disease.

Keywords: Sampson; endometriosis; endometrium; pathogenesis; stromal endometriosis; thoracic endometriosis.

Figure 1

Scheme of the pelvic and thoracic endometriosis. Endometrial glands with the surrounding stroma are the basic unit in the endometrium as shown with claudin-4 positive glands in brown. After tissue breakdown, most often by menstruation, the glands/stroma invade the myometrium, the pelvis, or extra-pelvic sites. The most probable and most common migration of the lands/stroma is via the fallopian tube into the pelvis (retrograde menstruation). However, very rarely the glands/stroma also invade via the right paracolic gutters the right diaphragm, the parietal and visceral pleura and sometimes even the lungs or some other extra-pelvic sites such as for example liver and brain (not shown). Very rarely, bilateral and left-sided invasions in the case of catamenial pneumothorax have been observed. In the case of hemoptysis, the vascular spread of the glands/stroma seems to be preferred. The different thickness of the arrows reflects the relative frequency of endometriosis at different ectopic sites. Modified from Omwandho et al. [54].