Hanna A. Scheuer

Jaw malformations plus displacement and numerical aberrations of teeth in neurofibromatosis type 1: a descriptive analysis of 48 patients based on panoramic radiographs and oral findings

AIM The aim of this study was to analyse jaw malformations and tooth displacement in patients with neurofibromatosis type 1 (NF1). MATERIAL AND METHODS Forty-eight patients were included in the study (male or female 24 each). All fulfilled the current NIH diagnostic criteria for NF1. The age range was 2.5-66 years. The type of neurofibroma was histologically proven in surgically treated patients. Patients with disseminated cutaneous neurofibromata and those with the plexiform type were distinguished. The analysis was based on physical investigation, photographs, panoramic radiographs and dental casts. RESULTS With the emphasis on alterations of tooth position, deformities of the adjacent bones and malocclusion, the majority of these patients (26) were affected by plexiform neurofibromata. In the other 22 patients with disseminated neurofibromata, malformations of the alveolar ridge were absent and individual oral symptoms were rarely found and were mild, and in all cases were unimpaired. Numerical aberrations and retention of molars was exclusively associated with a trigeminal nerve affected by plexiform neurofibroma. Aplasia of a second lower molar was recognized in four of these plexiform-neurofibroma patients. CONCLUSION It is widely accepted that malformations of the facial skeleton are often of genetic origin. However, in this study these malformations were strongly associated with plexiform neurofibromata originating from the trigeminal nerve. Thus, in addition to presently unknown genetic factors, the pattern of skeletal malformation can be caused by tumour invasion and local destruction, e.g. the neuromuscular unit or prenatal development of the plexiform neurofibroma in the inferior alveolar nerve. It is further concluded that epidemiologic studies on the incidence and severity of NF1 in the oral and maxillofacial region have to distinguish between patients with or without plexiform neurofibroma, especially when analysing alterations and deformities of the jaws, teeth and malocclusion. Aplasia of second inferior molars is an additional (dental) finding associated with plexiform neurofibromata in NF1.

Podoplanin expression in human tooth germ tissues and cystic odontogenic lesions: an immunohistochemical study.

BACKGROUND Podoplanin expression was described in mouse tooth germ and apical bud cells. The aim of this study was to analyse the podoplanin expression of human tooth germ tissues, adult teeth and odontogenic lesions immunohistochemically. STUDY DESIGN Nine human tooth germ biopsies and seven healthy permanent teeth extracted for orthodontic reasons were examined. Anti-podoplanin (D2-40) reactivity was investigated immunohistochemically. Five well-defined cystic odontogenic lesions (10 radicular cysts, 10 follicular cysts, three keratocystic odontogenic tumours, five ameloblastomas, and two adenomatoid odontogenic tumours) were analysed simultaneously. RESULTS Podoplanin expression was detected in the majority of epithelial and ecto-mesenchymal cells of human tooth germ tissues, odontoblasts and superficial dental pulp fibroblasts of permanent teeth. Cystic odontogenic lesions revealed positive reactions predominantly at the invasion front edge within basal epithelial layers. CONCLUSION Podoplanin appears to be involved in the orthologic and pathologic processes of the formation of elongated cell extensions and odontoblastic fibers, in the epithelial-mesenchymal transition and local invasion during tooth germ development as well as in both reactive and neoplastic odontogenic cystic lesions.

Unilateral Creeping Destruction of Deformed Mandibular Ramus and Angle Associated with Extensive Facial Plexiform Neurofibroma in Neurofibromatosis Type 1: A Case Report with Analysis of the Literature for Diagnosing Osteolytic Events of the Mandible in Tumor-suppressor Gene Syndrome

Neurofibromatosis type (NF1) is an autosomal dominant inherited tumor-suppressor gene syndrome of significant phenotypic variability with probable complete penetrance of the disease. Skeletal malformations of the skull belong to the phenotype of NF1. In the skull, defects of the calvaria and the sphenoid bone are diagnostically groundbreaking findings in NF1. Malformations of the facial skull are usually diagnosed in patients with NF1 in a topographical context with a plexiform neurofibroma (PNF). This report describes the rare occurrence of slowly advancing, unilateral destruction of proportions of the mandible in NF1, with the affected bone segment completely surrounded by a PNF. A malignant process was ruled out as a cause of partial organ loss. Various hypotheses on the pathogenesis of the rare finding are presented.