[Central lesions in neurofibromatosis: clinical, MRI and histopathologic correlations. An attempted classification]

The National Institute of Health Consensus Panel on Neurofibromatosis (NF) recently recognized 2 distinct forms of NF (NF-1 and NF-2) and stated that variant forms may exist. We selected 30 patients who fulfilled the criteria of NF-1 or whose condition was consistent with NF-2. All patients showed pathological magnetic resonance images (MRI), and in 19 cases confirmation was obtained from histopathology. We established correlations between the site and nature of the lesions on the one hand and the diagnostic criteria of NF on the other hand, there by hoping to contribute to a better knowledge and classification of neurofibromatosis. Nineteen patients had only intraparenchymatous lesions of the central nervous system (CNS) and fulfilled the criteria of NF-1; histopathological examination demonstrated pilocytic astrocytoma in 8 cases. Eleven patients showed only extra-axial lesions; 8 of them had criteria suggestive of NF-2, except for familial history. Pathological examination revealed either acoustic, pluriradicular, peripheral or mixed schwannomas (7/8) or pluriradicular ganglioneuromas (1/8). Two patients had unilateral extra-axial pluriradicular cervical lesions and fulfilled the diagnostic criteria of NF-1; pathological examination revealed neurofibroma in both cases. One female patient had both intra- and extra-axial lesions that fulfilled the criteria of NF-1 and NF-2, suggesting the existence of a mixed form (NF-3).