Hyperinnervation and mast cell activation may be used as histopathologic diagnostic criteria for vulvar vestibulitis

Vestibulitis is currently diagnosed based only on clinical criteria. To achieve histopathological diagnostic criteria, we carried out a computerized image analysis method.

Vestibular tissues removed from 40 women with severe vestibulitis were immunostained for mast cell count and degranulation by C-kit and mast cell tryptase, respectively. Vestibular nerve cells total area was evaluated after S-100 stain. Controls were 7 women aged 18-48. The images were converted to a digital signal, and analyzed using Image Proplus V4 software.

We found a significant increase in inflammatory infiltrate, number of mast cells and degranulated mast cells in vestibulitis compared to normal controls. The inflammatory cells were localized around the superficial minor vestibular glands. The total nerve fiber area was ten times higher in vestibulitis patients than in controls. A significant positive correlation was found between the total nerve fiber area and the number of mast cells in the vestibulitis group of patients.

We documented two diagnostic histopathological criteria for vestibulitis: (1) the presence of eight or more mast cells per 10 x 10 microscopic field, and (2) the total calculated area of the nerve fibers is ten times higher than expected. These findings re-establish the inflammatory nature of the vestibulitis. It is speculated that the trigger for the local outburst of nerve fibers could be related to the activation of the mast cells by a topical agent.