Posterior-Anterior Cephalometric Study of Neurofibromatosis Type 1 Patients With Facial Plexiform Neurofibroma: Analysis of Skeletal Symmetry Concerning Midfacial and Skull Base Reference Points (Zygomatic Arch, Mastoid, and Juga)

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.