Long-term Stable Unilateral Mandibular Deformity Associated With Ipsilateral Skull-base Soft-tissue Lesion and Degenerated Pterygoid Muscles in Neurofibromatosis Type 1.

BACKGROUND/AIM: Neurofibromatosis type 1 (NF1) is a tumor predisposition syndrome characterized by neoplasms originating from nerve sheath cells. The autosomal dominant hereditary disease also affects numerous developmental and metabolic processes, for example in the bones. The aim of the study was to document the diagnosis and treatment of an NF1 patient who had developed a space-occupying lesion at the base of the skull with noticeable mandibular changes.

CASE REPORT: The patient, who presented for her initial examination as a teenager, had an asymmetrical lower face. The deformation of the lower jaw mainly affected the left ramus and was associated with a deviation of the chin region toward the affected side. MRI revealed a diffuse plexiform neurofibroma (PNF) on the left side, which spread within the dystrophic pterygoid muscles. Over a treatment interval of 21 years, the patient developed numerous PNF in various regions of the body. The extent of the skull base tumor and the degree of muscular dystrophy remained constant during this period. Similarly, the mandibular dysplasia already noted during the initial examination remained unchanged.

CONCLUSION: Although mandibular dysplasias associated with PNF are rare findings in patients with NF1, they often have a characteristic pattern and may remain unchanged for decades. Knowledge of tumor-associated mandibular dysplasia in patients with NF1 is essential for the differential diagnosis of tumors in this region which can become malignant.