Differences in primary compared with secondary vestibulodynia by immunohistochemistry.

Objective: To assess whether primary and secondary vestibulodynia represent different pathologic pathways.

Methods: This was an analysis of archived vestibulectomy specimens from 88 premenopausal women with vestibulodynia (2002-2008). Patient records were reviewed to classify the type of vestibulodynia, duration of symptoms, and hormone status. Histologic sections were stained for hematoxylin and eosin to grade inflammation, S100 to highlight nerves, CD117 for mast cells, estrogen receptor α, and progesterone receptor. Differences between primary and secondary vestibulodynia were tested by t tests, chi-square analysis, and linear and logistic regression.

Results: Primary vestibulodynia showed significant neural hypertrophy and hyperplasia (P=.02, adjusted odds ratio [OR] 3.01, 95% confidence interval [CI] 1.2-7.6) and increased progesterone receptor nuclear immunostaining (P=.004, adjusted OR 3.94, CI 1.6-9.9) compared with secondary vestibulodynia. Estrogen receptor α expression was also greater in primary vestibulodynia when symptom diagnosis was less than 5 years (P=.004, adjusted OR 5.53 CI 1.71-17.91).

Conclusion: Primary and secondary vestibulodynia have significantly different histologic features, suggesting that they may have separate mechanistic pathways. Clinically, this may mean the discovery of distinct conditions.