Immunohistochemical analysis of thoracic endometriosis

The role of fibrosis in endometriosis: a systematic review

BACKGROUND

Fibrosis is an important pathological feature of endometriotic lesions of all subtypes. Fibrosis is present in and around endometriotic lesions, and a central role in its development is played by myofibroblasts, which are cells derived mainly after epithelial-to-mesenchymal transition (EMT) and fibroblast-to-myofibroblast transdifferentiation (FMT). Transforming growth factor-β (TGF-β) has a key role in this myofibroblastic differentiation. Myofibroblasts deposit extracellular matrix (ECM) and have contracting abilities, leading to a stiff micro-environment. These aspects are hypothesized to be involved in the origin of endometriosis-associated pain. Additionally, similarities between endometriosis-related fibrosis and other fibrotic diseases, such as systemic sclerosis or lung fibrosis, indicate that targeting fibrosis could be a potential therapeutic strategy for non-hormonal therapy for endometriosis.

OBJECTIVE AND RATIONALE

This review aims to summarize the current knowledge and to highlight the knowledge gaps about the role of fibrosis in endometriosis. A comprehensive literature overview about the role of fibrosis in endometriosis can improve the efficiency of fibrosis-oriented research in endometriosis.

SEARCH METHODS

A systematic literature search was performed in three biomedical databases using search terms for 'endometriosis', 'fibrosis', 'myofibroblasts', 'collagen', and 'α-smooth muscle actin'. Original studies were included if they reported about fibrosis and endometriosis. Both preclinical in vitro and animal studies, as well as research concerning human subjects were included.

OUTCOMES

Our search yielded 3441 results, of which 142 studies were included in this review. Most studies scored a high to moderate risk of bias according to the bias assessment tools. The studies were divided in three categories: human observational studies, experimental studies with human-derived material, and animal studies. The observational studies showed details about the histologic appearance of fibrosis in endometriosis and the co-occurrence of nerves and immune cells in lesions. The in vitro studies identified several pro-fibrotic pathways in relation to endometriosis. The animal studies mainly assessed the effect of potential therapeutic strategies to halt or regress fibrosis, for example targeting platelets or mast cells.

WIDER IMPLICATIONS

This review shows the central role of fibrosis and its main cellular driver, the myofibroblast, in endometriosis. Platelets and TGF-β have a pivotal role in pro-fibrotic signaling. The presence of nerves and neuropeptides is closely associated with fibrosis in endometriotic lesions, and is likely a cause of endometriosis-associated pain. The process of fibrotic development after EMT and FMT shares characteristics with other fibrotic diseases, so exploring similarities in endometriosis with known processes in diseases like systemic sclerosis, idiopathic pulmonary fibrosis or liver cirrhosis is relevant and a promising direction to explore new treatment strategies. The close relationship with nerves appears rather unique for endometriosis-related fibrosis and is not observed in other fibrotic diseases.

REGISTRATION NUMBER

N/A.

The Importance of Stromal Endometriosis in Thoracic Endometriosis

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.

PAX8: A Highly Sensitive Marker for the Glands in Extragenital Endometriosis

In cases of extragenital endometriosis or microscopic endometriosis lesions, pathological diagnosis can be challenging because endometriotic stroma and glands represent only a minor component of fibrotic endometriotic lesions. For better accuracy of diagnosis, the development of a sensitive and specific epithelial marker is beneficial. Previous studies showed that PAX8 is a highly sensitive and specific marker for primary and metastatic Mullerian epithelial tumors. Therefore, we sought to examine whether PAX8 is a highly sensitive marker for glands in extragenital endometriosis. Eight and 47 samples of ovarian endometrioma and extragenital endometriosis, respectively, were evaluated in this study. We calculated the percentage of samples positively immunostained for PAX8, CD10, estrogen receptor (ER), and progesterone receptor (PR). PAX8 was positive for endometriotic epithelial cells in 95.7% (45/47) of extragenital endometrioses and in 100% (8/8) of ovarian endometrioses. CD10 was positive for endometriotic stromal cells in 97.9% (46/47) of extragenital endometrioses. PAX8 was strongly positive for glands, even in a CD10-negative case. The expression of PAX8, CD10, and PR was not affected by preoperative hormonal therapy, and the positive rate of ER staining was significantly reduced by preoperative hormonal therapy. In conclusion, PAX8 is a highly sensitive epithelial marker for extragenital endometriosis. This specific expression was maintained under hormonal therapy. It is noteworthy that extragenital endometriosis maintains the expression of this lineage marker, although it occurs at various sites, and its cause and mechanism of development might be different. PAX8 nuclear expression can be useful in detecting extragenital endometriosis in clinical practice.

Extra-pelvic endometriosis: A review

BACKGROUND

Extra-pelvic endometriosis is a rare type of endometriosis, which occurs in a distant site from gynecological organs. The diagnosis of extra-pelvic endometriosis can be extremely challenging and may result in a delay in diagnosis. The main objective of this review was to characterize abdominal wall endometriosis (AWE) and thoracic endometriosis (TE).

METHODS

The authors performed a literature search to provide an overview of AWE and TE, which are the major types of extra-pelvic endometriosis.

MAIN FINDINGS

Abdominal wall endometriosis includes scar endometriosis secondary to the surgical wound and spontaneous AWE, most of which occur in the umbilicus or groin. Surgical treatment appeared to be effective for AWE. Case reports indicated that the diagnosis and treatment of catamenial pneumothorax or endometriosis-related pneumothorax (CP/ERP) are challenging, and a combination of surgery and postoperative hormonal therapy is essential. Further, catamenial hemoptysis (CH) can be adequately managed by hormonal treatment, unlike CP/ERP.

CONCLUSION

Evidence-based approaches to diagnosis and treatment of extra-pelvic endometriosis remain immature given the low prevalence and limited quality of research available in the literature. To gain a better understanding of extra-pelvic endometriosis, it would be advisable to develop a registry involving a multidisciplinary collaboration with gynecologists, general surgeons, and thoracic surgeons.

Thoracic endometriosis presenting as a catamenial hemothorax with discordant video-assisted thoracoscopic surgery

Thoracic endometriosis is uncommon and may be overlooked, resulting in a delay in diagnosis. We describe the case of a 47-year-old woman presenting with acute onset pleuritic pain and hemothorax secondary to this rare entity. The diagnosis of thoracic endometriosis is driven by a compatible clinical history coupled with supportive imaging and immunohistochemical findings. Imaging features lack specificity, however, computed tomography and magnetic resonance imaging play an important role in identifying pleural/diaphragmatic involvement and excluding other more common diseases. Immunohistochemical pleural fluid analysis can confirm the presence of hormone receptor-positive endometrial glands and stroma. We illustrate a few potential diagnostic pitfalls, specifically the inconsistency in diagnostic yield of video-assisted thoracoscopic surgery/thoracentesis and the variable temporal association of patients’ symptoms and pathology with menstruation. Prompt identification of thoracic endometriosis is important as it enables early institution of therapy and limits future complications.

Thoracic endometriosis syndrome at University of Ilorin Teaching Hospital

Background

Endometriosis is defined as the presence of endometrial tissue (stroma and functional glands) outside the uterine cavity in women of reproductive age. Ectopic sites are frequently located in the pelvis; extrapelvic sites have been reported in the gastrointestinal tract and thoracic cavity. Thoracic manifestation of endometriosis constitutes thoracic endometriosis syndrome (TES).

Objectives

To examine the presentation pattern and outcome of in the management of TES.

Methods

This study is a retrospective review of medical records of patients diagnosed with endometriosis at the University of Ilorin Teaching Hospital over a 3.5-year period from January 2014 to June 2017.

Results

A total of 21 patients presented with endometriosis, of whom 8 (38.1%) presented with TES. The most common variety of TES was catamenial pleural effusion (CPE) accounting for 75%, followed by catamenial chest pain (37.5%). Two patients (25%) each presented with catamenial pneumothorax and catamenial haemoptysis, while 1 (12.5%) had catamenial surgical emphysema. Closed thoracostomy tube drainage plus chemical pleurodesis was the most frequent intervention technique, accounting for 62.5%.

Conclusion

TES remains an uncommon entity, despite being the most common extrapelvic manifestation of endometriosis. CPE appeared to be the most common variant of TES in our environment. Currently available treatment options need to be improved, and more use made of video-assisted thoracoscopic surgery.

Diagnosis of thoracic endometriosis with immunohistochemistry

Background

Pathological and immunohistochemical features of thoracic endometriosis are not well understood. In the present study, we retrospectively analyzed the clinical and pathological diagnostic characteristics of 55 female pneumothorax cases.

Methods

This study was a retrospective observation of 55 women aged from 8 to 62 years old who underwent surgery for pneumothorax from November 2001 through January 2018. Immunohistochemistry for estrogen receptor (ER), progesterone receptor (PR), and CD10 was performed for all cases. As controls, we analyzed resected specimens of spontaneous pneumothorax in men who received surgery.

Results

Of 55 cases, endometrial stroma and glands by Hematoxylin-Eosin (HE) stain was found in only one case. Thirty-seven cases (67.3%) were ER- and PR-positive in stromal bland spindle cells of the lung. The remaining 18 cases (32.7%) were ER-, PR-, and CD10-negative. The ER- and PR-positive specimens could be further classified according to 2 staining patterns: 'scattered pattern' and 'aggregated pattern'. Thirty-three cases (60.0%) were scattered and four cases (7.3%) were aggregated pattern. Only the aggregated pattern specimens exhibited positive staining for CD10. As the scattered pattern was also found in men, we only diagnosed the aggregated pattern cases as endometriosis.

Conclusions

A diagnosis of thoracic endometriosis is simple when both endometrial stroma and gland are present. In cases of endometriosis with stroma only, a further classification of "aggregated pattern", in which immunohistochemistry is ER-, PR- and CD10-positive might be necessary for diagnosis.

Cellular Changes Consistent With Epithelial-Mesenchymal Transition and Fibroblast-to-Myofibroblast Transdifferentiation in the Progression of Experimental Endometriosis in Baboons

We have recently shown that platelets play important roles in development of endometriosis and proposed that endometriotic lesions are essentially wounds that undergo repeated tissue injury and repair (ReTIAR). Further investigation indicated that endometriotic lesions, stimulated by platelet-derived transforming growth factor β1 (TGF-β1), activate the TGF-β1/Smad3 signaling pathway and undergo epithelial-mesenchymal transition (EMT) and fibroblast-to-myofibroblast transdifferentiation (FMT), resulting in increased cellular contractility and collagen production and increased smooth muscle metaplasia (SMM), leading to fibrosis. Using serially dissected endometriotic tissue samples from baboons with induced endometriosis, we tested the hypothesis of progressive EMT, FMT, SMM, and fibrosis through TGF-β1/Smad activation using immunohistochemistry and immunoflurescence staining analyses. We found that platelets are aggregated in endometriotic lesions, and vimentin expression was increased in the epithelial compartment of the lesions as they progressively developed. We also found that the number of smooth muscle cells (SMCs) appeared to increase with time as lesions progressed and was concomitant with the increased vimentin-positive glandular epithelial cells in the lesions. As lesion development progressed, TGF-β1 and phosphorylated-Smad3 staining was elevated and the number of α-smooth muscle actin-positive myofibroblasts and highly differentiated SMCs increased in the stromal compartment, which correlated with the increasing extent of fibrosis. These results, taken together, provide support for the notion that ReTIAR occurs in the endometriotic lesions, resulting in EMT and FMT, leading to SMM and ultimately fibrosis as lesions progress. Consequently, our data also provide corroborative evidence that platelets drive the EMT and FMT in endometriotic lesions over time, promoting SMM and resulting ultimately in fibrosis in the endometriotic lesions. These findings cast a new light on the natural history of endometriosis which so far has been elusive.