[Orbitotemporal segmental neurofibromatosis].

Introduction: Neurofibromatosis is a rare pathology with heterogeneous clinical presentation.

Observation: We report a case of a right orbitotemporal plexiform neurofibroma in a 64-year-old woman with von Recklinghausen's neurofibromatosis. A craniofacial CT scan, with injection, showed a heterogeneous tumor in front of the skull base and the temporoparietal bone with no intracranial extension but an extension into the maxillary sinus and nasal cavity. In summery, she presented orbitotemporal segmental neurofibromatosis type 1 because of the unilateral lesion. She had a first surgery to remove her jugal and preauricular tumor with an exenteration, which provided an eye histology. The histology found no Lisch nodules but a cellular proliferation causing choroidal hyperplasia. We noted neurofibromin on choroidal cells and normal cells in addition to pathologic cells (Schwann cells and melanocytes), meaning that two cell populations were obtained in the same tissue: a somatic mosaicism.

Discussion/conclusion: We advance the hypothesis that there was a regulation of cellular growth in a particular microenvironment because of the absence of tumor. To identify and confirm the somatic mosaicism, we would need a FISH analysis (probes containing sequences of the NF1 gene with a probe specific for the chromosome 17 centromere).