Haemangioblastomas are the key central nervous system manifestation of von Hippel-Lindau (VHL) disease, which is caused by germline mutation of the VHL gene. We have recently shown that 'tumour-free' spinal cord from patients with VHL disease contains microscopic, poorly differentiated cellular aggregates in nerve root tissue, which we descriptively designated 'mesenchymal tumourlets'. Here we have investigated spinal cord tissue affected by multiple tumours. We show that a small subset of mesenchymal tumourlets of extends beyond the nerve root to form proliferative VHL-deficient mesenchyme and frank haemangioblastoma. We thus demonstrate that tumourlets present potential, but true precursor material for haemangioblastoma. We further show that intraradicular tumourlets consist of scattered VHL-deficient cells with activation of HIF-2α and HIF-dependent target proteins including CAIX and VEGF, and are associated with an extensive angiogenic response. In contrast, activation of HIF-1α was only observed in the later stages of tumour progression. In addition, ultrastructural examination reveals gradual transition from poorly differentiated VHL-deficient cells into vacuolated cells with a 'stromal' cell phenotype. The evolution of frank haemangioblastoma seems to involve multiple steps from a large pool of precursor lesions.
- Hypoxia-inducible factor
- Nerve root
- VHL disease
ASJC Scopus subject areas
- Pathology and Forensic Medicine