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Clinical Problem: Neurofibromatosis type 1 (NF1) and tuberous sclerosis (TS) are among the most common genetic diseases. Bone and soft tissue manifestations are common disease manifestations., Standard Radiological Procedure and Evaluation: The standard radiological procedure is magnetic resonance imaging (MRI). All macroscopic disease manifestations can be diagnosed radiologically and observed during the course. Specific complications such as plexiform neurofibromas and malignant peripheral nerve sheath tumors (MPNST) in NF1 are readily visible on MRI. Differentiation of plexiform neurofibromas and MPNST is uncertain and requires follow-up., Recommendation for Practice: MRI is the most important procedure for the investigation of soft tissue and bone manifestations of NF1 and TS., (© 2021. Springer Medizin Verlag GmbH, ein Teil von Springer Nature.)

Aim: The aim of this study was to determine the malformations of the maxillary sinus in neurofibromatosis type 1 patients (NF1)., Material and Methods: Twenty-two patients with NF1 were investigated clinically and radiologically: 11 had an unilateral trigeminal plexiform neurofibroma and 11 had multiple cutaneous neurofibromas. The histological type of NF was ascertained in all cases following tumor resections. The malformation of the maxillary sinus was assessed on plain radiographs and computed or magnetic resonance tomograms. Intraindividual side comparison was used to judge the size of the sinus and its position in the midface., Results: In patients with cutaneous neurofibromas the maxillary sinus appeared symmetrical in size and position. The pneumatization of the sinus had no abnormalities on the radiographs. Malformations of the maxillary sinus were restricted to plexiform neurofibromas. On the side affected by a plexiform NF, the sinus appeared hypoplastic and caudally displaced due to an enlarged ipsilateral orbit. The expansion of the sinus to the lateral side was impaired, obviously due to tumor masses. Consecutively, the alveolar process of the affected side was also displaced leading to a complex malocclusion., Discussion: Malformations of the face are frequently presented as case reports in the literature. Emphasis is given to the elephantiasis-like tumor growth of the face in certain patients with NF1. The underlying pathology has not yet been fully understood. This report provides evidence that in the midfacial region the overgrowth is predominantly caused by the plexiform neurofibroma itself and that the bones can even be hypoplastic and show scoliosis-like malformation compared to the nonaffected side. These findings are relevant when debulking procedures of the face are planned for NF1 patients.

Neurofibromatosis type 1 (NF1) is an autosomal dominant hereditary disease of high penetrance and variable expression. Epidemiologic data on craniofacial manifestations are still lacking. Up until now 74 patients with NF1 have been treated at the Department of Oral and Maxillofacial Surgery of the University of Hamburg. Forty-two patients presented periorbital and orbital neurofibromas varying in extension and in the severity of findings of the affected site. Surgical therapy is mainly based on tumour reduction, frequently combined with face-lifting. In our experience neurofibromas of the neck tend to be pseudo-encapsulated, facilitating the preparation of the tumour. On the other hand, identification and preparation of diffuse infiltrating neurofibromas in the trigeminal nerve region are difficult and local recurrence must be expected.