Abstract

50 cases of Schwannomas were studied for the differences between peripheral and central type tumors. There were 28 central and 22 peripheral cases. The morphological studies were performed in HE staining considering the ratio of Antoni A and Antoni B components, incidence of Verocay’s bodies and vascularization of neoplasms. The immunophenotype was evaluated with the use of S-100, GFAP, CD31 and CD34 antibodies. CD31 antibody was used to assess vascular density. The obtained results were compared taking under consideration the localization of tumors (central vs peripheral) and AA and AB components.

Results. In the central tumors AA and AB components were equally represented. In the peripheral cases AA component was more prevalent in smaller tumors, while in the bigger ones AB component was seen more frequently. Verocay’s bodies were more frequently seen in the central tumors. The types of vascular changes in both components included: thick- wall hyalinized vessels, telangiectases, haemangiomas and microvascular proliferation. Hyalinization and telangiectases were more prominent within AB component. The vascular density in the examined cases ranged from 16 to 271 vessels/mm2. The quantity of microvessels with diameter below 10 µm ranged from 28% to 84% of all counted vessels with no relation to the localization of tumor. The majority of vessels (about 60%) were smaller than 10 µm within the tumors with predominance of AA, while in the other tumors this type of vessels was discernible less frequently (under 50%). These differences are statistically significant (p=0.025, U Man-Whitney test). There were no differences between central and peripheral tumors considering the frequency of vascular changes and vascular density. All tumors were S-100 – positive, however its expression was more intense in AB areas. GFAP staining was present in AA areas in half of the cases and was particularly pronounced in the retroperitoneal tumors. CD34 expression was found in subcapsular regions within all tumors and within parenchymal cells only within AB component.

Conclusions. Main histological differences between central and peripheral Schwannomas concern: the quantity of AB component, the frequency of Verocay’s bodies and GFAP expression.. The components AA and AB show different immunophenotype, which can be summarized as: AA: S-100(+++), CD34(-), GFAP(+/-), high percentage small vessels; AB: S100(+), CD34(+), GFAP(-), percentage of small vessels below 50%.

Adres: Rafał Pęksa
Katedra i Zakład Patomorfologii AMG
e-mail: rafalpeksa@gumed.edu.pl