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.