Supratentorial intraventricular schwannoma of the choroid plexus

Intraventricular Neurilemmoma (Schwannoma): Shall GFAP Immunostaining Be Regarded as a Histogenetical Tag or as a Mere Histomimetical Trait?

“…Etiopathogenesis of such a neoplasm within the cerebral ventricles is perplexing and, hence, several hypotheses have been introduced [ 3 – 7 ]: (1) growth from autonomic nerve cells inherent to choroid plexus or from nervi vasorum , a premise based on the identification of the former by Benedikt in 1874 and confirmed by Stöhr in 1922 [ 33 , 34 ] (also, the apparent attachment to choroid plexus supports this conjecture), (2) development from displaced neural crest cells which, in turn, may give rise to ectopic Schwann cells, and (3) neoplastic transformation of multipotent stem cells . Although no sole speculation may be sufficient to explain every single case—as different, nonexcluding mechanisms shall be involved—recent advances in the recognition of the so-called “neural stem cells” make the third assumption particularly attractive.…”

“…Interestingly, it is well known that, in contrast to their peripheral counterpart, non-cranial nerve related neurilemmomas are more prone to diffusely express GFAP [ 3 ]. Unfortunately, just a couple of reports emphasise this difference and demonstrate it in their photographs [ 5 – 7 ]. In this regard, we share the opinion of Luo et al [ 4 ] stating that at least this subset of neurilemmomas arises from neoplastic transformation of subventricular pluripotent stem cells, hence preserving parental GFAP (+) immunophenotype which may in fact represent some kind of histogenetical imprinting .…”

“…The clinical presentation of intraventricular neurilemmomas generally involves headache, nausea, and vomiting; however, brachial-crural hemiparesis, seizures, vertigo, and visual symptoms such as homonymous hemianopsia and transient scintillating scotomas have also been reported [ 3 – 7 ]. On the other hand, common neuroradiological features include a heterogeneously enhancing, predominantly solid mass with intralesional cysts and overstressed peritumoural oedema [ 3 – 7 ].…”

“…Differential diagnoses in our setting include cystic ventricular-extending astrocytoma, cystic meningioma, ependymoma, choroid plexus papilloma or carcinoma, haemangioblastoma, and metastatic lesions [ 3 , 5 – 7 ]. Some morphological traits such as absence of papillary stalks lined by a single layer of uniform cuboidal/cylindrical epithelial cells, nonattendance of plump lipid-laden multivacuolated stromal cells, or lack of foreign carcinomatous/sarcomatous invading cells easily discard the latter by simple light microscopy examination.…”