(003) Immunohistochemical Staining of Vestibular Tissue from Patients Suspected of Having Neuroproliferative Vestibulodynia: A Case Series
Authors: Goldstein I , Uloko M , Goldstein A 
Published: June 2023

Abstract

Introduction
Neuroproliferative vestibulodynia (NPV) is a genetic form of vestibulodynia associated with increased density of mast cells and nerves in vestibular tissue. In congenital NPV, umbilical hypersensitivity and a history of absent pain-free penetration including tampon insertion is associated. In acquired NPV, entrance dyspareunia often occurs after severe or recurrent candidiasis or allergic reaction to a topical agent. The diagnosis of NPV is primarily made by excluding other forms of vestibulodynia including: pelvic floor muscle hypertonicity (in part because of pain throughout the entire vestibule); dermatologic pathology (e.g. lichen sclerosus, lichen planus) is absent; inflammatory pathology (e.g. vaginitis, candidiasis) is absent; hormonally-mediated pathology is ruled- out (normal calculated free testosterone or following unsuccessful treatment with local vestibular testosterone/estradiol or systemic testosterone); and cauda equina or pudendal nerve pathology is ruled out (vestibular anesthesia testing temporarily eliminates pain). Few providers performing surgical treatment of NPV by complete vestibulectomy and vaginal advancement flap reconstruction confirm the increased density of CD117-positive cells (consistent with mast cells) and PGP9.5 positive cells (consistent with nerves) in the vestibular epithelium and/or stroma of excised vestibular tissue specimens.

Objectives
To confirm the diagnosis of NPV, surgical specimens from patients undergoing complete vestibulectomy were examined using immunohistochemical staining to observe if there was an increased density of CD117-positive cells and PGP9.5 positive cells in the vestibular epithelium and/or stroma, consistent with excess mast cells and nerves, respectively.

Methods
Vestibular tissues were placed in fixed formalin paraffin embedded blocks. 5 um sections from each block were stained with hematoxylin and eosin and the slides analyzed by light microscopy. Antibodies to CD117 and PGP 9.5 were used for immunostaining. Multiple regions of the immunohistochemically stained slides were examined and photographed using a Zeiss AxioCam HR high resolution digital microscopy. The density of CD117-positive cells and PGP9.5 positive cells were determined by counting the number of dark brown stained cells in a high-power field (HPF = x 20 magnification). Specimens from control subjects have values of 8 mast cells or less per hpf as reported by Bornstein.

Results
Specimens from 21 women (mean age 29+/−13 years) who had complete vestibulectomy with vaginal advancement flap surgery between June 2019 and November 2020 underwent immunohistochemical staining, with NPV confirmed in all. High densities of both CD117-positive cells (mean density of 39+/−15 per HPF) in vestibular epithelium and stroma, and high densities of PGP9.5-positive cells (mean density of 27+/−16 per HPF) were noted in vestibular stroma in all specimens. Figures 1 and 2 show CD117-positive cells and PGP9.5 positive cells, consistent with excess mast cells and nerves, respectively. Findings and photos of immunohistochemical staining are shared with patients post-operatively, which validates the surgery for them.

Conclusions
Patients are empowered knowing the underlying pathology of their entrance dyspareunia which was previously only suspected to be NPV. Future considerations include pre-operative vestibular biopsies to determine the necessity of surgery and immunohistochemical staining with calcitonin gene-related peptide to determine the possibility of medical management of NPV.

Disclosure
No.