Objective: Secretory meningiomas constitute a relatively rare subtype of meningiomas and present often with massive peritumoural oedema. From our previous report, a high number of mast cells were demonstrable in this subtype of meningiomas. The present study aimed to obtain more information about mast cell derived progangiogenic factors and mediators as well as VEGF receptors in secretory meningioma. Additionally, the correlation of histological factors such as the presence of mast cells and the radiological evidence of surrounding tumour oedema was analysed.
Material and Method: Sixteen cases of secretory meningioma were examined. Relevant clinical information was obtained from the patient files. The peritumoural oedema was determined either by CT or MRI scans and graded as mild, moderate and severe. Immunohistochemical studies of histamine, substance P, serotonin, VEGF and VEGF receptors were performed. A
double-blind quantitative evaluation of mast cells staining positively for VEGF in a comparison with total mast cells in
secretory meningiomas was made by two histopathologists.
Results: There was no immunoreactivity against histamine or substance P within the tumour tissue or in mast cells. Fine
granules of serotonin were demonstrated within the mast cells and a coarse granular expression of VEGF was found within the mast cells. Our preliminary data demonstrated that tumours with moderate to severe degree of peritumoural oedema usually contained more than 50% of VEGF-staining positive mast cells.
Conclusion: Secretory meningiomas are characterized by a significantly increased number of mast cells. VEGF and serotonin might be involved in the pathophysiological process of this vasogenic brain oedema. The preliminary data demonstrated the potential relation between the radiological evidence of increasing oedema and the high numbers of mast cell staining positively for VEGF.

Keywords: Mast cells, Peritumoural oedema, Secretory meningioma, Serotonin, VEGF