A three-dimensional morphological reconstruction of uterine leiomyoma pseudocapsule vasculature by the Allen-Cahn mathematical model

Submucous Fibroids, Fertility, and Possible Correlation to Pseudocapsule Thickness in Reproductive Surgery

Background and Objectives

Fibroids are related to infertility. Fibroid pseudocapsule is a neurovascular bundle surrounding leiomyomas rich of neurofibers involved in myometrial biology. Authors evaluated, by a case-control study, the fibroid pseudocapsule (FP) thickness by ultrasound (US) and the histological measurements, according to uterine location of fibroids.

Methods

137 consecutive patients undergoing hysterectomy for uterine myomas were enrolled and 200 myomas were evaluated. Before surgery, patients underwent an ultrasound (US) investigation to evaluate the number, the size, and the location of fibroids. After surgery, myoma-pseudocapsule-myometrium specimens were measured and evaluated by a single expert pathologist. Both US and histological data were collected and statistically analyzed.

Results

Our results confirm the relevant difference of FP thickness, particularly represented under the endometrium for submucous LMs. FPs near the endometrial cavity were considerably thicker than those of both intramural fibroids and subserous fibroids measured by US (P=0.0001) and histology (P=0.0001). A clear cut-off measurement at 2 mm (P=0.0001) was found between endometrial FPs and all other FPs for either US or histology measurements.

Conclusion

The thickness of FP is considerably higher near the endometrial cavity when compared to those of both intramural and subserous LMs, suggesting a potential role either in fertility or in myometrial healing.

A combined ultrasound and histologic approach for analysis of uterine fibroid pseudocapsule thickness

Authors investigated 75 patients with uterine myomas, appraising whether fibroid pseudocapsule (FP) thickness varies depending on fibroid location, by a prospective cohort trial (level of evidence II-2) settled in University-affiliated Hospitals. Uteri were scanned via bidimensional and power Doppler ultrasound (US) to map the fibroids and record the FP thickness, prior to hysterectomy for symptomatic uterine fibroids. After hysterectomy, FP specimens were sampled and analyzed by pathologists. Ultrasound and histology data were matched. Pseudocapsule thickness of 108 fibroids was measured: subserosal fibroids (SSFs), intramural fibroids (IMFs), and fibroids near the endometrial cavity (FEC). The FEC's pseudocapsules were considerably thicker than those of IMF and SSF measured by US and histology (P = .001). A clear cutoff existed between FEC pseudocapsule thickness and all other pseudocapsules, with significant differences observed at 2 mm (P = .001). Similarity between histological and US measurements was observed only with IMF pseudocapsules, whereas FEC or SSF showed significant differences. The pseudocapsule of fibroids is considerably thicker near the endometrial cavity when compared to those of both IMFs and SSFs. Since fibroids closest to the endometrial cavity are the most involved in fertility and infertility and FP is considerably thicker near the endometrial cavity, it is possible to hypothesize an involvement of FP of fibroid near the endometrium since FP contains many neuropeptides and neurotransmitters that are physiologically active, even if these data may take on a broader meaning in a study on a larger number of patients.

Gene expression analysis reveals an angiogenic profile in uterine leiomyoma pseudocapsule

The pseudocapsule (PC) of the uterine leiomyoma (UL) is an anatomic entity that surrounds the myoma separating it from the myometrium (UM). Although a number of microarray experiments have identified differences in gene expression profile in the UL when compared with the UM, there is a lack of systematic studies on the PC. In this study, quantitative RT-PCR analysis was performed on 18 matched PC, UL and UM specimens and results showed that the PC displays a specific gene expression profile. The low expression level of insulin-like growth factor (IGF-2), a fibroid specific marker, that we found in the PC and the UM when compared with the UL, clearly indicates that the PC is in structural continuity with the UM. However, the significant increase in endoglin expression level in PC with respect to the UL and UM indicates that an active neoangiogenesis is present in PC. Conversely, other angiogenic factors such as von Willebrand factor (vWF) and vascular endothelial growth factor A (VEGF-A) seem to have little influence on the PC angiogenesis. Because the endoglin is preferentially expressed in proliferating endothelial cells, whereas the vWF and VEGF-A are preferentially expressed in preexisting endothelial cells, our idea is that the angiogenic activity in the PC is linked to wound healing. The angiogenic activity is also sustained by intermediate expression level of cystein-rich angiogenesis inducer 61, connective tissue growth factor and collagen 4α2 genes all involved in the neoangiogenesis, that we detected in the PC. Taken together our data demonstrate that the specific expression pattern observed in the PC could be the response of the uterine wall's smooth cells to the tension imposed by the tumor. As a consequence, a neovascular structure is generated involving regenerative processes. For these reasons, we suggest that the laparoscopic intracapsular myomectomy (LIM), a new surgical technique that preserves the PC during the UL removal, should always be preferred, to favor a faster and proper uterine healing.

Uterine fibroid pseudocapsule studied by transmission electron microscopy

OBJECTIVE

The fibroid pseudocapsule is a structure which surrounds the uterine fibroid, separates it from the uterine tissue and contains a vascular network rich in neurotransmitters like a neurovascular bundle. The authors examined the composition of the fibroid pseudocapsule using electron microscopy.

STUDY DESIGN

Twenty non-pregnant patients were submitted to laparoscopic myomectomy by the intracapsular method and samples of the removed pseudocapsules were analyzed using transmission electron microscopy.

RESULTS

At the ultrastructural level the pseudocapsule cells have the features of smooth muscle cells similar to the myometrium. So, the pseudocapsules are part of the myometrium which compresses the leiomyoma.

CONCLUSION

This ultrastructural feature suggests that when removing fibroids their pseudocapsules should be preserved. This study confirms preliminary evidence that pseudocapsules contain neuropeptides together with their related fibers, as a neurovascular bundle. The surgeon's behavior should be directed to carefully control and spare this muscular surrounding tissue during fibroid excision, in order to preserve the myometrium as much as possible.

Surgical management of neurovascular bundle in uterine fibroid pseudocapsule

The uterine fibroid pseudocapsule is a fibro-neurovascular structure surrounding a leiomyoma, separating it from normal peripheral myometrium. The fibroid pseudocapsule is composed of a neurovascular network rich in neurofibers similar to the neurovascular bundle surrounding a prostate. The nerve-sparing radical prostatectomy has several intriguing parallels to myomectomy. It may serve either as a useful model in modern fibroid surgical removal, or it may accelerate our understanding of the role of the fibrovascular bundle and neurotransmitters in the healing and restoration of reproductive potential after intracapsular myomectomy. Surgical innovations, such as laparoscopic or robotic myomectomy applied to the intracapsular technique with magnification of the fibroid pseudocapsule surrounding a leiomyoma, originated from the radical prostatectomy method that highlighted a careful dissection of the neurovascular bundle to preserve sexual functioning after prostatectomy. Gentle uterine leiomyoma detachment from the pseudocapsule neurovascular bundle has allowed a reduction in uterine bleeding and uterine musculature trauma with sparing of the pseudocapsule neuropeptide fibers. This technique has had a favorable impact on functionality in reproduction and has improved fertility outcomes. Further research should determine the role of the myoma pseudocapsule neurovascular bundle in the formation, growth, and pathophysiological consequences of fibroids, including pain, infertility, and reproductive outcomes.

The management of fibroids based on immunohistochemical studies of their pseudocapsules

BACKGROUND

We examined the presence of collagen IV and laminin in the pseudocapsule of uterine myomata to clarify different ultra-structural characteristics and their possible role in the management of this condition.

METHODS

Twenty non-pregnant patients underwent laparoscopic intracapsular myomectomies. Samples of the removed fibroids pseudocapsules were analyzed by immunochemical staining for collagen IV, immunohistochemical location of the vascular membrane-bound laminin and quantitative analysis of their images.

RESULTS

In the blood vessels of the pseudocapsules, a reduction in laminin and increase in collagen IV with increasing diameter of fibroids was noted. These proteins are related to loss of the basal membrane and to ageing of the tissue. The increase of collagen IV is linked to the increase of amorphous substance, including glycosaminoglycans and glycoproteins.

CONCLUSION

Based on immunohistochemical findings, the authors propose to remove fibroids in women seeking pregnancy whilst respecting the pseudocapsule by neurofibre sparing in the incision site. This is essential for optimal muscular healing and myometrial function in future pregnancies, and also when fibroids remain under 6 cm diameter, especially in young women wishing pregnancies. Fibroid removal should be performed before the myoma reaches a size causing compression of the surrounding tissues, which results in the loss of regenerative potential.