N. Kadlub

NRAS Mutation Is the Sole Recurrent Somatic Mutation in Large Congenital Melanocytic Nevi

Congenital melanocytic nevus (CMN) is a particular melanocytic in utero proliferation characterized by an increased risk of melanoma transformation during infancy or adulthood. NRAS and BRAF mutations have consistently been reported in CMN samples, but until recently results have been contradictory. We therefore studied a series of large and giant CMNs and compared them with small and medium CMNs using Sanger sequencing, pyrosequencing, high-resolution melting analysis, and mutation enrichment by an enhanced version of ice-COLD-PCR. Large-giant CMNs displayed NRAS mutations in 94.7% of cases (18/19). At that point, the role of additional mutations in CMN pathogenesis had to be investigated. We therefore performed exome sequencing on five specimens of large-giant nevi. The results showed that NRAS mutation was the sole recurrent somatic event found in such melanocytic proliferations. The genetic profile of small-medium CMNs was significantly different, with 70% of cases bearing NRAS mutations and 30% showing BRAF mutations. These findings strongly suggest that NRAS mutations are sufficient to drive melanocytic benign proliferations in utero.

Clonogenic Cell Subpopulations Maintain Congenital Melanocytic Nevi

Large congenital melanocytic nevi (lCMN) are benign melanocytic tumors associated with an increased risk of melanoma transformation. They result predominantly from a post-zygotic somatic NRAS mutation. These lesions persist and even increase after birth proportionally to the childs growth. Therefore, we asked here whether cells with clonogenic and tumorigenic properties persisted postnatally in lCMN. Subpopulations of lCMN cells expressed stem cell/progenitor lineage markers such as Sox10, Nestin, Oct4, and ABCB5. In vitro, 1 in 250 cells from fresh lCMN formed colonies that could be passaged and harbored the same NRAS mutation as the original nevus. In vivo, lCMN specimens xenografted in immunocompromised mice expanded 4-fold. BrdU(+)-proliferating and label-retaining melanocytes were found within the outgrowth skin tissue of these xenografts, which displayed the same benign nested architecture as the original nevus. lCMN cell suspensions were not able to expand when xenografted alone in Rag 2-/- mice. Conversely, when mixed with keratinocytes, these cells reconstituted the architecture of the human nevus with its characteristic melanocyte layout, lentiginous hyperplasia, and nested architecture. Overall, our data demonstrate that, after birth, certain lCMN cell subtypes still display features such as clonogenic potential and expand into nevus-like structures when cooperating with adjacent keratinocytes.

Giant chondrolipoma of the tongue in a 14-year-old child with mandibular hypertrophy. Isolated lesion or regional overgrowth syndrome

Chondrolipoma is a rare condition; especially in the oral cavity. The authors described a giant chondrolipoma of the tongue, associated with mandibular and lower lip overgrowth, in a 14-year-old boy. After tumour excision, histopathological examination showed mature cartilage within lobules of mature adipocytes. This is the first case of giant chondrolipoma associated with facial overgrowth. The aetiology and the association with a localized Proteus syndrome are discussed.

Morsures de chien à la face chez l’enfant : étude rétrospective de 77 cas

INTRODUCTION The face is the area most vulnerable for dog bites in children. Surgical management is an emergency to prevent infection, functional and aesthetic outcomes. The aim of this study was to define a new gravity scale, and to determine a prevention policy. PATIENTS AND METHODS In our maxillofacial and plastic surgery department, we conducted a retrospective study from 2002 to 2010, including 77 children under 16 years old, victims of facial dog bite. We analyzed epidemiological, clinical data, surgical outcomes. RESULTS The mean age was 5.36 years. Dogs were principally represented by class I and II dogs; 27,7% of them had ever bitten before. In almost all the cases, the dogs belong to the family or closers. Twenty-one percent of children belong to an unfavourable social environment; 71.43% of dog bites interested the central area of the face. The bites were deep in 77% of cases with amputation or extensive loss of substance in 31% of cases. The healing time was 10.54 months. Nearly a third of patients required several surgeries; 41.56% of patients had aesthetic and functional sequelae; 35.1% of children had psychological problems afterward. CONCLUSION Facial children dog bites require a multidisciplinary approach, and a long-term follow-up. We propose a new classification of dog bite severity, more appropriate to the face.

Intraosseous haemangioma: semantic and medical confusion

The literature is rich in case reports of intraosseous haemangioma, although most of these are actually cases of venous or capillary malformations. To illustrate this confusion in terminology, we present three cases of slow-flow vascular malformations misnamed as intraosseous haemangioma. A retrospective study of children diagnosed with intraosseous haemangioma was conducted. Clinical and radiological data were evaluated. Histopathological examinations and immunohistochemical studies were redone by three independent pathologists to classify the lesions according to the International Society for the Study of Vascular Anomalies (ISSVA) and World Health Organization (WHO) classifications. Three children who had presented with jaw haemangiomas were identified. Computed tomography scan patterns were not specific. All tumours were GLUT-1-negative and D2-40-negative. The lesions were classified as central haemangiomas according to the WHO, and as slow-flow malformations according to the ISSVA. The classification of vascular anomalies is based on clinical, radiological, and histological differences between vascular tumours and malformations. Based on this classification, the evolution of the lesion can be predicted and adequate treatment applied. The binary ISSVA classification is widely accepted and should be applied for all vascular lesions.

Craniofacial phenotype in the branchio-oculo-facial syndrome: four case reports

Branchio-oculo-facial syndrome represents a craniofacial disorder in which affected patients may develop a wide range of distinctive features that include cleft lip and/or palate, cervical aplastic skin defect, malformed pinna, and ocular anomalies. This study reports four new cases confirmed by the identification of mutations in the TFAP2A gene and describes in detail the findings in the craniofacial region. The four cases included two familial and two sporadic, and three have been followed since the birth. Two out of the four cases showed atypical features. One patient presented brainstem immaturity with dysregulation of sympathetic and parasympathetic systems, which have so far not been described in the literature and were associated with anxiety, panic attacks, and tiredness. Another patient had as an additional feature a hypoplastic thumb with distal implantation.

Varying proliferative and clonogenic potential in NRAS -mutated congenital melanocytic nevi according to size

Congenital melanocytic nevi (CMN) are benign proliferations that may be associated with various consequences depending on their size. They are characterized by a specific molecular signature, namely a postzygotic somatic NRAS or BRAF mutation. We have recently reported that large CMN (lCMN), which are classically associated with an increased melanoma risk, harbour cell subpopulations with specific clonogenic and tumorigenic potential. We wished to ascertain whether cells displaying similar properties persisted postnatally in medium CMN (mCMN). Eighteen medium M1, nine large and one giant NRAS‐mutated CMN were prospectively included in the study. Subpopulations of mCMN cells expressed stem cell/progenitor lineage markers such as Sox10, nestin and Oct4, as was the case in lCMN. Nevertheless, conversely to lCMN, mCMN cells with clonogenic properties were rarer. In vitro, approximatively one in 1500 cells isolated from fresh mCMN formed colonies that could be passaged. In vivo, mCMN seemed to harbour cells with less proliferative potential than the larger lesions as lCMN biopsies displayed a threefold expansion compared to mCMN when xenografted in Rag2−/− mice. Thus, our data revealed variations in clonogenicity and tumorigenic properties in NRAS‐mutated CMN according to size.

Tumeurs kératokystiques odontogènes de l’enfant et syndrome de Gorlin. Comment expliquer les récidives et l’agressivité des lésions ?

INTRODUCTION Keratocystic odontogenic tumors (KOT), as complications in Nevoid Basal Cell Carcinoma Syndrome (NBCCS), occur early (before 20 years of age) and are usually more aggressive. The aim of this retrospective study was to determine the clinical, histological, and genetic phenotype, of these lesions and to define predictive features of aggressiveness. PATIENTS AND METHODS We retrospectively studied five patients presenting with one or several KOT with NBCCS. We collected their clinical, radiological, and therapeutic data, rate of recurrence or new localization. Anatomopathological examinations were reviewed systematically. Somatic PTCH, SMO and SMAD 4 sequencing were completed. RESULTS The average age at diagnosis was 11.2 years. The average number of KOT was 3.2 most often located in the molar region. All the cysts were enucleated. Anatomopathological examination revealed the presence of satellite cysts and daughter cysts and epithelial expansion in more than 80% of cases. No somatic mutation was observed among KOT. DISCUSSION KOT develop in the first 10 years, in patients presenting with NBCCS, and recurrence is observed in the second and third decade. KOT are typically aggressive and have a tendency to recur, especially in patients with NBCCS. Anatomopathological examination may be predictive of the lesions aggressiveness. Understanding the genetic and immunological mechanisms should open the way for new medical treatment.

Proliferative Nodules vs Melanoma Arising in Giant Congenital Melanocytic Nevi During Childhood

Importance The differential diagnosis between proliferative nodules (PNs) and melanoma arising in congenital melanocytic nevi (CMN) is crucial, as patients with PNs most often experience no increased risk of melanoma with metastases and death. Objective To analyze the utility of immunohistochemistry and fluorescence in situ hybridization (FISH) in distinguishing PNs from childhood and adult-onset melanoma arising in CMN. Design, Setting, and Participants A case series was conducted from June 29, 1989, to November 12, 2009, of 13 children with PNs arising in CMN in childhood and 5 children with melanomas arising in CMN in childhood. Five patients with giant CMN with no nodules were included as negative controls, and 6 patients with melanomas arising in CMN in adulthood were included as positive controls. Follow-up ranged from 3 to 21 years in all children (mean, 9.9 years) and from 3 months to 7 years in adults. Specimens were selected for immunohistochemistry and FISH. All histopathologic sections were reviewed by 2 dermatopathologists who examined all nodules arising at different ages in the same patient and, in the case of melanoma, all locations. Data analysis was performed from January 1, 2013, to January 31, 2015. Main Outcomes and Measures The ability to distinguish melanoma from PN using immunohistochemistry and/or FISH. Results Of the 13 patients (5 boys and 8 girls) with PNs present at birth, all PNs were stable (mean follow-up, 9 years). Eight patients with PNs and 4 of 5 patients with childhood-onset melanoma showed homogeneous staining for HMB45, while heterogeneous staining for HMB45 was seen in 3 of 6 patients with adult-onset melanoma. Expression of p16 was strongly positive in most patients with childhood-onset PNs (10 of 11 patients) and melanoma (all patients) but negative in 4 patients with adult-onset melanoma. Patients with PNs and the 5 patients with childhood-onset melanoma had numerical chromosomal aberrations never observed in the adjacent CMN. The 2 children with FISH-positive PNs are melanoma free after 7 and 4 years. Only 1 patient with childhood-onset melanoma had a FISH aberration compared with 4 patients with adult-onset melanoma. Conclusions and Relevance Immunohistochemistry and the 4-probe FISH melanoma analysis are not useful for distinguishing PN from childhood-onset melanoma as opposed to adult-onset melanoma. Numerical anomalies seen in PNs but not in the adjacent CMN could be the result of a chromosomal segregation malfunction resulting in the development of nodules.

PTCH1 mutation and local aggressiveness of odontogenic keratocystic tumors in children: is there a relationship?

Keratocystic odontogenic tumors (KCOTs) are locally aggressive jaw lesions that may be related to PTCH1 mutations in isolation or in association with nevoid basal cell carcinoma syndrome. We sought to clarify the role of PTCH1 mutation in KCOT aggressiveness. We assessed cyst pathological characteristics, Ki-67 immunostaining, and somatic and germinal PTCH1 mutation in 16 KCOTs from 10 unrelated patients. Ten PTCH1 mutations were identified in 16 tumors. All tumors with PTCH1 mutations presented the criteria of pathological aggressiveness. We also noted the presence of a chorionic epithelial structure apparently acting as a secondary germinal center in these same tumors. Ki-67 immunostaining was not associated with PTCH1 mutation. KCOTs harboring the mutation display a chorionic epithelial structure that acts as a secondary germinal center. Genetic and microenvironmental factors might interact to propel tumor development.