Segmental Ipsilateral Odontognathic Dysplasia (Mandibular Involvement in Segmental Odontomaxillary Dysplasia?) and Identification of PIK3CA Somatic Variant in Lesional Mandibular Gingival Tissue

Abstract

Segmental odontomaxillary dysplasia (SOD) is a developmental condition of the middle and posterior maxilla featuring dysplastic bone overgrowth, dental abnormalities and, occasionally, various homolateral cutaneous manifestations. Herein, we describe an individual with maxillary abnormality akin to SOD and associated ipsilateral segmental odontomandibular dysplasia. Also, the result of the evaluation of lesional mandibular gingival tissue for overgrowth-related gene variants is reported. An 8-year-old girl presented clinically with congenital maxillary and mandibular alveolar soft tissue enlargement in the area of the premolars. A panoramic radiograph revealed abnormal trabeculation essentially similar to SOD in the maxilla and mandible with congenitally missing maxillary and mandibular first and second premolars and mandibular canines. Diagnostic mandibular bone biopsy was performed and lesional mandibular gingival hyperplastic tissue was obtained for variant analysis of somatic overgrowth genes PIK3CA, AKT1, AKT3, GNAQ, GNA11, MTOR, PIK3R2. Cone beam computerized tomography (CBCT) disclosed osseous abnormalities on the left side of the maxilla and mandible and very mild osseous expansion in the mandible. Histologically, abnormal bone exhibiting prominent reversal lines was present and associated with fibrocollagenous tissue. Genomic DNA analysis disclosed PIK3CAc.1571G>A; pArg524Lys which was seen at a low mosaic level in the blood, indicating a post-zygotic change. Although this case may be a unique disorder, by sharing features with SOD, one can suggest the possibility of mandibular involvement in SOD. The presence of a PIK3CA variant may support the hypothesis that these segmental disorders could be part of the PIK3CA-related overgrowth spectrum.

Pediatric Gnathic Bony and Mesenchymal Tumors

“…Polubothu et al 60 in 2020 made note of a recurrent somatic variant in ACTB on chromosome 7:5568275 in 3 patients and in ACTB on chromosome 7:5528646, the first of which has been described with Becker nevi. 61 Additionally, Gibson et al 62 in 2019 described a case with findings similar to that of SOD but with mandibular involvement that harbored a somatic PIK3CA c.1571G>A; pArg524Lys mutation. The authors note that this finding has unknown significance according to the Standards and Guidelines by the American College of Medical Genetics.…”

Die neue WHO-Klassifikation der Kiefertumoren

“…Der Verlauf der SOD ist gutartig, eine modellierende Abtragung kann allerdings aus kosmetischen und/oder funktionellen Gründen erforderlich sein. Interessanterweise wurden bei betroffenen Patient:innen Low-level-Mosaik-Variationen im PIK3CA -Gen gefunden, die auf einen Zusammenhang mit anderen PIK3CA -assoziierten Overgrowth-Syndromen hinweisen [ 10 ].…”