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Background/aim: Neurofibromatosis type 1 (NF1) is an autosomal dominant tumor predisposition syndrome that is also characterized by skeletal abnormalities. In the cranial region, skeletal dysplasia is observed that is associated with a characteristic peripheral nerve sheath tumor, the plexiform neurofibroma (PNF). The aim of the study was to determine PNF-associated skeletal asymmetries of the mid-skull and skull base as an indicator of local tumor development., Patients and Methods: The distances of the zygomatic arch, mastoid, and juga measurement points from the interorbital horizontal plane and median sagittal plane were examined on anterior-posterior cephalograms of 168 NF1 patients (females: 82, males: 86) and compared with the findings of a control group. A distinction was made as to whether the patients had developed a facial PNF., Results: The distances of the measurement points from the reference planes differed between the patient and control group (p<0.05). Within the NF1 patients, differences between certain distances were noted when comparing patients with PNF and without PNF (p<0.05). In PNF patients, discrete changes in the skull contour were also detectable on the non-affected side (p<0.05). The caudal measurement point of the skull base showed no changes in the group comparison., Conclusion: The individually very variable facial PNF in NF1 is associated with deformations and misalignments of midfacial bones that follow a pattern quantifiable with cephalometric analysis., (Copyright © 2022 International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.)

Background/aim: Xenografted benign tumours in immunodeficient mice provide an in vivo model to study tumour biology and the effect of agents on tumour growth. Conventionally, these small grafts can only be monitored upon sacrificing the animals. We evaluated ultrasound biomicroscopy for monitoring such grafts in vivo., Materials and Methods: Small fragments (<10 mm(3)) of a plexiform neurofibroma obtained from patients with established diagnosis of neurofibromatosis type-1 (NF1) were orthotopically-xenografted onto the sciatic nerve of immunodeficient mice and monitored using a high-resolution in vivo micro-imaging system., Results: Grafts were identified in most cases and were distinguished from the surrounding inflammatory host tissues by detailed ultrasonographic signals. Graft sizes could be calculated precisely from serial scan sections and monitored during the whole course of drug treatment., Conclusion: High frequency sonographic measurement is a superior non-invasive method for monitoring small grafts of slowly growing benign tumours in mice in vivo, e.g. plexiform neurofibroma, and is especially suitable for tracing the effects of drugs at multiple time-points, thus allowing a very cost-effective follow-up.

Unlabelled: Neurofibromatosis type 1 (NF1) is an autosomal dominant inherited disease. Some stigmata of NF1 occur in the orbital region. The aim of this study was to reveal whether alterations of the orbital rim visible on plain radiographs may indicate the presence of a plexiform neurofibroma (PNF), a tumour almost exclusively diagnosed in NF1., Material and Methods: The plain orbital radiographs of 73 patients with NF1 (female: N=37, male: N=36) were investigated for alterations of the orbit. The group was further distinguished according to the presence of orbital PNF (N=53) and/or sphenoid wing dysplasia (N=30). Radiographs from patients with NF1 and with exclusion of PNF in the orbitofacial region were used for comparison (N=20). A special cephalometric analysis (Dental Vision™) was adapted to the demands of this study., Results: Patients with NF1 not affected by an orbitofacial PNF exhibited symmetrical orbits. Unilateral increase in orbital height was associated with ipsilateral PNF. The width of orbits affected by a PNF was often slightly increased compared to the non-affected side. The determination of cephalometrically-defined angles disclosed an erection of the PNF-affected orbit compared to the medio-sagittal plane., Conclusion: Plain radiographs are often the first diagnostic measure used to determine skeletal alterations. This study shows that certain parameters of the orbital rim are useful indicators of a PNF in patients who are unilaterally affected by this lesion in the orbital or orbitotemporal region.

A 19-year-old female with established neurofibromatosis type 1 (NF1) diagnosis and history of malignant peripheral nerve sheath tumour (MPNST) of the lower extremities showed a tumour of her right upper extremity with a maximum standardised uptake value (SUV) of 5.7 on positron emission/computerised tomography (PET/CT) scan. The extirpated tumour proved to be an atypical plexiform neurofibroma. Immunohistochemical investigations revealed a strong positive reaction of tumour cells for S-100 protein. Epithelial membrane antigen (EMA)-positive perineural cells were demonstrated at the border of the tumour. Scattered nerve fibres were labelled with neurofilament antibodies within the tumour. The maximum Ki-67 labelling index reached 9%. Slight to moderate podoplanin expression of the tumour cells was noted in areas of fibrillary growth. Podoplanin expression has been proposed as a differentiation marker for schwannomas and neurofibromas. This atypical neurofibroma showed a high SUV on PET that is indicative for MPNST. It appears likely that subtypes of Schwann cells express podoplanin. This marker may be useful in distinguishing different Schwann cell populations in neurofibromas.