Combined Soft and Hard Tissue Facial Lesions In Early Childhood Pioneering the Diagnosis of the Tumor Predisposition Syndrome Neurofibromatosis Type 1.

Background/Aim: Neurofibromatosis type 1 (NF1) is an autosomal dominant hereditary tumor predisposition syndrome. The haploinsufficiency of the cells of NF1 patients is also evident in skeletal development and maintenance. Bone deformities of the facial skull often occur early in life and are topographically associated with a certain nerve sheath tumor, the plexiform neurofibroma (PNF), which is considered a precursor to malignant degeneration. The aim of the study was to analyze skeletal changes in the jaw and teeth over a longer period to differentiate between tumor-associated, development-dependent, and adaptive processes. Case Report: The male patient, who was 2 years and 9 months old at the time of the initial examination, had developed a right-sided facial PNF. The patient, who underwent multiple surgical procedures, was examined clinically and radiologically over a period of 12.5 years. The follow-up examination revealed both the progression of the deformity in the ramus and jaw angle area and the influence of the local tumor on tooth development. However, radiological findings showed that the tumor-coated bone was capable of adaptive functions such as maintaining the condyle-fossa relationship despite significant dystrophy, and that the emergence of permanent teeth was an indicator of the preservation of the local differentiation capacity of the hard tissue, which must be ensured over many years to be successful. Conclusion: The analysis of jaw dysmorphia and the examination of the stages of dentition are valuable diagnostic aids for assessing the dysplastic component of an often-disfiguring facial tumor, which in rare cases can transform into a malignant peripheral nerve sheath tumor. In individual cases, dental findings can provide clues for estimating the timing of the interaction between PNF and hard tissues which can apparently date back to the prenatal phase. The skeletal findings can already be identified on plain radiographs of the skull.