Intravascular and intramyofibre growth of pericranially invading meningiomas

In meningiomas extending into pericranial structures, phenomena of invasive growth are observed that have been little known up to now in this onkotype but are of differential diagnostic importance in these locations. 6 out of 10 meningiomas invading the ethmoidal sinus and/or skeletal muscles showed intravasal extension of tumour cells in small vessels of the neighbouring tissue. In 5 out of 7 cases with muscle invasion next to interstitial growth, the spreading of meningioma cells within isolated myofibers could be observed. As shown by enzyme- and immunohistochemical methods, the latter survived for a longer time in spite of active mitotic proliferation and axial spreading of the tumour cells within the sarcoplasm tube. A relation to peculiarities of histology, growth activity and clinical course does not seem to exist.