Tau-associated neuropathology in ganglion cell tumours increases with patient age but appears unrelated to ApoE genotype

Ganglion cell tumours, including gangliogliomas and gangliocytomas, are low grade neoplasms with a mature neuronal component. Ganglion cells within these lesions occasionally exhibit neurodegenerative changes including neurofibrillary tangles (NFT) similar to those in Alzheimer's disease. The frequency and spectrum of degenerative pathology in these lesions have not been defined, nor has their relation to patient age or factors such as apolipoprotein E (ApoE) genotype that predispose to Alzheimer's disease. We studied 72 ganglion cell tumours (61 gangliogliomas, 11 gangliocytomas) from patients 7 months to 72-years-old. Haematoxylin and eosin (H&E), silver stains (Hirano method) and immunohistochemistry for tau, α-synuclein and β-amyloid were performed on formalin-fixed, paraffin-embedded tissue from surgical specimens. Tau-and silver-positive NFT and neuropil threads (NPT) were present in four of 26 ganglion cell tumours from patients over 30-years-old (ages 31, 38, 50, and 58 years). Neuronal granulovacuolar degeneration (GVD) was noted in five of 26 tumours from patients over 30-years-old (mean, 48 years). NFT, NPT, and GVD were not seen in ganglion cell tumours from patients under 30-years-old[0/46]. Cytoplasmic argentophilic bodies distinct from NFT were present in five of 26 tumours from patients over 30-years-old and in two of 46 under 30 years. Neither α-synuclein positive neuronal inclusions nor β-amyloid immunoreactivity was noted in ganglion cell tumours from any age group. The distribution of ApoE genotypes was similar among those tumours that contained tau-associated neuropathology and those that did not. Neurodegenerative changes are uncommon in ganglion cell tumours, but increase in frequency with patient age. GVD, tau-positive NFT and NPT, and argentophilic bodies occur more often in ganglion cell tumours from patients over 30-yrs-old, but do not appear to be associated with a specific ApoE genotype.