Clinicopathologic growth factors in vestibular schwannomas: a morphological and immunohistochemical study of 69 tumours.

Tumour growth of vestibular schwannomas is still difficult to predict. The aim of our study was to determine whether any defined histopathological feature was correlated with the clinical course. We did a retrospective study with 69 paraffin-embedded tumours to establish whether the number of vessels, blood cells extravasation or degree of inflammation, all semi-quantitatively assessed, could be indicative of potential of growth. An immunohistochemical study was also performed with an endothelial marker CD34, the leukocyte common antigen CD45 and the estrogen and progesterone hormone receptors. All these parameters were correlated with patient's age, duration of symptoms (d), with a clinical growth index (CLI = tumour size/d). No clinical parameters proved to be predictive of tumour growth. Tumour size was significantly (p = 0.01) related to the number of vessels and we found a significant relationship between the clinical growth index (CLI) and total number of vessels, especially when duration of symptoms lasted less than 1 year (p < 0.001). However, we found no relationship between duration of symptoms or CLI and CD34 index. The degree of inflammation was significantly correlated (p = 0.007) with duration of symptoms when it lasted more than 1 year. The CD45 index and the semi-quantitative evaluation of the inflammation were well correlated (p = 0.001). No estrogen receptors antigenic site was detected and only seven tumours expressed progesterone receptor in a few cells without any significant clinical value. These results suggest that vessel density is determinant for sporadic acoustic neuroma growth especially for a short clinical course.