Relationship between endometriotic foci and nerves in rectovaginal endometriotic nodules

The histological relationships between fibrotic tissue, endometriotic foci and nerves in the rectovaginal septum endometriotic or adenomyotic nodule w ere studied. This is considered to be one of the most severe forms of deep endometriosis, Masson's trichrome staining for fibrosis detection and immun ohistochemistry with the S100 monoclonal antibody for nerve detection were performed in 28 rectovaginal endometriotic nodules from patients presenting with severe dysmenorrhoea and deep dyspareunia (23 patients with no other endometriotic location or potential cause of pain at laparoscopy and ultras onography; five patients with multiple pelvic endometriotic localizations a nd other potential causes of pain at laparoscopy), Patients were allocated to two groups on the basis of their preoperative pain scores for pelvic pai n, dysmenorrhoea and deep dyspareunia (group 1, score >7; group 2, score le ss than or equal to 7), For each symptom, the mean number of nerves and end ometriotic lesions per high-power field and the mean largest diameter of th e lesions were not statistically different in groups 1 and 2, The mean perc entages of nerves located within the fibrosis of the nodule and within endo metriotic lesions were significantly higher in group 1 than in group 2, Amo ng nerves located within endometriotic lesions, there was a significantly h igher proportion showing intraneurial and perineurial invasion by endometri osis in group 1 than in group 2, In rectovaginal endometriotic nodules, the re was a close histological relationship between nerves and endometriotic f oci, and between nerves and the fibrotic component of the nodule, We postul ate that such topographical relationships could at least partially explain the strong association between this lesion and pain.