Case 1 - 63year old gentleman who presented with cauda equina syndrome. MRI revealed an intrathecal mass lesion displacing the cauda equina nerve roots. He underwent surgical resection in November 2021 with histology showing neuroendocrine cells with immunohistochemistry staining consistent with a spinal paraganglioma. Succinate Dehydrogenase (SDH) was retained. Plasma metanephrines post-operatively were normal, with no symptoms of catecholamine excess. Genetic testing revealed no pathogenic variants. DOTATATE-PET scan postoperatively showed no additional sites of avidity.
Case 2 - 55 year old lady who presented with increasing lower back and right leg pain. MRI spine showed an L4/5 intradural extramedullary lesion, she underwent spinal surgery in February 2023 with complete resection. Histology showed features consistent with a NET. Cells stained positive for keratin, synaptophysin and chromogranin. Ki67 proliferation index was <1%. SDHA and SDHB staining was retained. Post-operative plasma metanephrines were normal, no symptoms of catecholamine excess were noted.Specific genetic testing was negative. DOTATATE-PET scan post operatively was also unremarkable.
Paragangliomas (PGL) are extra-adrenal neuroendocrine tumours arising from neural crest cells migrating to ganglia of the autonomic nervous system and can be either sympathetic or parasympathetic in origin. Sympathetic PGLs secrete catecholamines whereas parasympathetic lesions are non-functional1,2. Approximately 40% of patients with PGLs have a hereditary disease-specific germline mutation. In the remaining ~60% that occur sporadically, at least 30% have a somatic mutation3.
Primary CNS NETs are rare and most commonly occur in the cauda equina region4,5. Cauda equina NETs are no longer classified as cauda equina PGLs because they are morphologically, molecularly and histogenetically distinct from PGLs1,6. The main distinguishing feature is having an epithelial as well as neuronal component1. Unlike PGLs, cauda equina NETs are almost always hormonally silent, cytokeratin positive, GATA3 negative and HOXB13 positive1,7. They aren’t associated with hereditary germline mutations and are generally indolent6,7.