Open Access

Lorenz Dörner, Vitor Goncalves, Elisa-Maria Suhm, Vanessa Ries, Jens Schittenhelm, Marcos Tatagiba, Felix Behling

• Background: The size of vestibular schwannomas shows marked variations, ranging from small intrameatal lesions to giant tumors that compress multiple structures of the cerebellopontine angle (CPA). Giant vestibular schwannomas are defined by a CPA diameter of at least 40 mm and factors that are associated with giant size at clinical presentation are still poorly understood. Methods: A retrospective analysis of 907 sporadic vestibular schwannomas that were treated at our center were analyzed for clinical and immunohistochemical factors that are associated with giant tumor size. Age, gender, tumor status (primary vs. recurrent tumor), prior radiotherapy, volumetric tumor size, and immunohistochemical markers of proliferation (MIB1), lymphocyte infiltration (CD3 and CD8) and macrophage infiltration (CD68 and CD163) were analyzed. Results: Overall, 36 of 907 tumors (4.0%) were giant vestibular schwannomas and were associated with cyst formation (p<0.0001) and higher expression scores forBackground: The size of vestibular schwannomas shows marked variations, ranging from small intrameatal lesions to giant tumors that compress multiple structures of the cerebellopontine angle (CPA). Giant vestibular schwannomas are defined by a CPA diameter of at least 40 mm and factors that are associated with giant size at clinical presentation are still poorly understood. Methods: A retrospective analysis of 907 sporadic vestibular schwannomas that were treated at our center were analyzed for clinical and immunohistochemical factors that are associated with giant tumor size. Age, gender, tumor status (primary vs. recurrent tumor), prior radiotherapy, volumetric tumor size, and immunohistochemical markers of proliferation (MIB1), lymphocyte infiltration (CD3 and CD8) and macrophage infiltration (CD68 and CD163) were analyzed. Results: Overall, 36 of 907 tumors (4.0%) were giant vestibular schwannomas and were associated with cyst formation (p<0.0001) and higher expression scores for macrophage marker CD163 (p<0.0001). There were no differences in age, gender, prior radiotherapy, recurrent tumor status, MIB1 expression, CD68, CD3 and CD8 expression. In the multivariate nominal logistic regression cyst formation and higher CD163 expression were associated with giant size. Conclusions: Giant vestibular schwannomas are associated with cystic growth and show an increased infiltration with CD163 positive macrophages.…