Late-Onset of Keratocysts in De Novo Mutation c.1347+1G>A on Intron 9 PTCH1-(NBCCS) – Diagnosis and Therapy

Introduction: The occurrence of two main symptoms (calcification of the falx cerebri, odontogenic keratocysts, basal cell carcinoma) and a minimum of one secondary symptom is necessary for de-novo diagnosing a Basal Cell Nevus Syndrome (BCNS). Late diagnosing is usual if the primary symptoms are absent. Subtypes of BCNS may express phenotypes at different ages. Early recognition is needed. The adhesion of keratocysts to the basal bone layer varies, so different treatment options are standard. Aim: A 47-year-old woman without clinical signs of BCNS except macrocephaly suffered from de-novomutation of the PTCH1 gene. Odontogenic keratocysts were recognized sporadically by CB-CT ten years later, as late-onset; Compared to subsequent generations, who often present the main symptoms in childhood. The indication of resection, marsupialization, or enucleation with or without Carnoy-solution is a clinical decision. Conclusion: Despite 100% penetrance, intrafamilial expression of the clinical phenomenon is variable. In child morbidity, the parents’ lifelong co-screening should be mandatory by radiological and clinical investigation. Late-onset KCOT should be resected en-bloc, including soft tissue movement. Enucleation has less morbidity for mandibular keratocysts near the nerve. Carnoy-solution helps minimize the risk of relapse. © 2020 Manfred Nilius. Hosting by Science Repository. All rights reserved


Introduction
Gorlin-Goltz-Syndrome (basal cell nevus syndrome (BCNS)) is wellknown for a prevalence of 1:50.000 to 1:150.000 and was first described by Gorlin et al. in 1960 [1]. It is a hereditary disease, an autosomal dominant trait characterized by high penetration and variable phenotypical expression [2]. A direct molecular genetic test confirms germline mutation in the PTCH1 gene chromosome 9q22. 32. A multidisciplinary approach is necessary since the clinical symptoms often begin in adolescents, in the case of medulloblastomas, even in early childhood [3,4]. Patients older than 20y have calcification of the falx [5]. Pathognomonic for BCNS are keratocystic odontogenic tumors (KCOT) in the jaws and multiple basal cell carcinomas. Skeletal abnormities are pits, bifid ribs, hypertelorism, and macrocephaly. They should be carefully detected [6][7][8][9]. For maxillofacial regions, a CB-CT is favourable for diagnostic reasons [10,11].

Aim
Parental generations should have genetic counseling by a specialist after detecting a mutation of the long arm of the chromosome 9q22.3 (PTCH1) in subsequent generations. To detect main symptoms like calcification of the falx cerebri, odontogenic keratocysts, basal cell carcinomas, and secondary symptoms (e.g., macrocephaly, cleft lip and palate, spine/rib abnormalities or polydactyly). Therefore, secondary symptoms often appear earlier and should receive more attention to avoid the extent of the destruction. There are various options for treating keratocysts: marsupialization enucleation, and block resection [12,13].

I Diagnosis
A 47-year-old woman suffered from a de novo mutation c.1347+1G>A on Intron 9 PTCH1-Gene and suspected BCNS. Diagnostical staging results in main symptoms: Calcification of the falx cerebri ( Figure 1) and odontogenic keratocysts (Figures 2 & 3). So far, no basal cell carcinomas and point-shaped pits in the palmoplantar skin have appeared. Evident as secondary symptoms macrocephaly, strabismus, hypertelorismus, and bifid ribs appeared.

II Treatment
Due to the strong adhesion of the maxilla keratocysts, we resected enblock with piezo-surgery [Piezosurgery® touch, Saw OT7A, Mectron-Deutschland, D-Köln]. For 3 minutes, we plugged a cotton swab soaked in freshly prepared Carnoy's solution [absolute alcohol 6 mL, chloroform 3 mL, glacial acetic acid 1 mL, ferric chloride 0.1 gm/mL; Engelbrecht Labortechnik, Edermünde, Germany] as chemical cauterization [20,21]. For facial reconstruction, we used the Bichat fat pad for closure. The keratocysts showed macroscopically clinically different colorations with partly yellowish discoloration. Enucleation removed the multicystic keratocysts in the mandible. We used Carnoy-solution for intraluminal injection and post excavatum as chemical cautery of the bony cavity [19]. Tooth 36, which was in the cyst cluster, was osteotomized. We filled the cavity by using the PRGF technique, according to Anitua et al. 2012 [22].

Histological Examination of KCOT
The multilayer squamous epithelium is in line and has an orthokeratotic part of cystic walls (Figure 8). The surface is wave-shaped and palisade like reserve cells. The basement membrane is intact. Horn materials and macrophages peeled off in the lumen. Subepithelial and alternately dense and perivascular accentuated lymph plasma cell infiltrate. Areas with curly collagenous fiber tissue include sparse myelinated nerve fibers. The bony parts show vital osteocytes. The bone lamellae have slightly irregular putty lines and loose collagen fiber tissue. They accumulated sparse associations of a multilayered epithelium with a giant cell reaction around cholesterol voids (Figure 9).

I Diagnosis
KCOT are frequently diagnosed incidentally [1,5,13,23]. To avoid extensive lesions, frequent dental check-ups and multimodal therapy are necessary [24][25][26]. Furthermore, genetic counseling of the entire family is recommendable due to the dominant inheritance. The mother's 11year-old boy had early onset of multiple keratocyst, macrocephaly, hypertelorism, and calcification of the falx cerebri [25]. The sister was not affected by the BCNS but showed bifid ribs like her mother. The family was informed about the high risk of recurrence of keratocysts and basal cell carcinoma development.
Diagnoses are often backward detected, as described by Yordonova et al. 2007, who investigated late detection of multiple keratocysts of a 50year-old mother after screening a BCNS in her 18-year-old daughter [27]. If BCNS is suspected, family examinations sometimes show pair mutations. In the case-report described by Hedge et al., a 38-year-old mother was co-screened with her eight-year-old daughter, who showed odontogenic keratocytes [28]. A meta-analysis of the syndromic keratocystic odontogenic tumor is presented by Antonoglu et al. 2014 [29]. Individuals with BCNS mutations showed a wide range of clinical variations. Pastorino et al. (2005) investigated the genotype/phenotype correlation in BCNS and concluded that carrier and type of mutation did not influence when the patients developed oral keratocysts or basal cell carcinoma. They recommend lifetime supervision in the case of BCNS [30]. Twin-examination shows multiple keratocysts in almost identical areas, as described by Anchlia et al. (2015) [31].

Conclusion
Clinical expression of symptoms is variable despite a penetrance of 100%. In the case of child morbidity, the parents' lifelong co-screening should be mandatory by radiological and clinical investigation. Radical resection of late-onset KCOT appears to be a sure option in syndromic cases, including soft tissue movement. For non-syndromic cases, the literature advocates enucleation with the application of Carnoy-solution or as first line-treatment to minimize the risk of relapse.

Consent
The patient gave written consent for publication. The author ensure that the work described has been carried out in accordance with The Code of Ethics of the World Medical Association (Declaration of Helsinki). The manuscript is in line with the Recommendations for the Conduct, Reporting, Editing and Publication of Scholarly Work in Medical