Multifocal Pigmented Villonodular Synovitis in the Noonan Syndrome

Genetically confirmed coexistence of neurofibromatosis type 1 and Cherubism in a pediatric patient

BACKGROUND

Neurofibromatosis type 1 (NF1) is an autosomal dominant disorder typified by various combination of numerous Café-au-lait macules, cutaneous and plexiform neurofibromas, freckling of inguinal or axillary region, optic glioma, Lisch nodules and osseous lesions. Cherubism is a rare genetic syndrome described by progressive swelling of the lower and/or upper jaw due to replacement of bone by fibrous connective tissue. Patients are reported in the literature with NF1 and cherubism-like phenotype due to the NF1 osseous lesions in the jaws. The purpose of this case report is the description of a young male genetically diagnosed with both NF1 and cherubism.

METHODS AND RESULTS

A 9 years and six month old patient with clinical findings of NF1 and cherubism in whom both diseases were genetically confirmed, is presented. The patient was evaluated by a pediatrician, a pediatric endocrinologist, an ophthalmologist, and an oral and maxillofacial surgeon. A laboratory and hormonal screening, a histological examination, a chest X-ray, a magnetic resonance imaging (MRI) of the orbit and a digital panoramic radiography were performed. Genetic testing applying Whole Exome Sequencing was conducted.

CONCLUSIONS

A novel and an already reported pathogenic variants were detected in NF1 and SH3BP2 genes, respectively. This is the first described patient with coexistence of NF1 and cherubism. The contribution of Next Generation Sequencing (NGS) in gene variant identification as well as the importance of close collaboration between laboratory scientists and clinicians, is highlighted. Both are essential for optimizing the diagnostic approach of patients with a complex phenotype.

Imatinib, a New Adjuvant Medical Treatment for Multifocal Villonodular Synovitis Associated to Noonan Syndrome: A Case Report and Literature Review

Noonan syndrome (NS) is an autosomal dominant multisystem disorder caused by the dysregulation of the Rat Sarcoma/Mitogen-activated protein kinase (RAS/MAPK) pathway and characterized by short stature, heart defects, pectus excavatum, webbed neck, learning disabilities, cryptorchidism, and facial dysmorphia. Villonodular synovitis is a joint disorder most common in young adults characterized by an abnormal proliferation of the synovial membrane. Multifocal Villonodular synovitis is a rare disease whose recurrent nature can make its management particularly difficult. Currently, there is no systemic therapy recommended in diffuse and recurrent forms, especially because of the fear of long-term side effects in patients, who are usually young. Yet, tyrosine kinase inhibitors seem promising to reduce the effects of an aberrant colony stimulating factor-1 (CSF-1) production at the origin of the synovial nodule proliferation. We present here the case of a 21-year-old woman with NS associated to diffuse multifocal villonodular synovitis (DMVS). Our clinical case provides therapeutic experience in this very rare association. Indeed, in association with surgery, the patient improved considerably: she had complete daily life autonomy, knee joint amplitudes of 100° in flexion and 0° in extension and was able to walk for 10 min without any technical assistance. To our knowledge, this is the first case of a patient suffering from DMVS associated with a Noonan syndrome treated with Glivec® (oral administration at a dosage of 340 mg/m2 in children, until disease regression) on a long-term basis.

Case Report: Safety and Efficacy of Denosumab in Four Children With Noonan Syndrome With Multiple Giant Cell Lesions of the Jaw

Noonan syndrome is a genetic disorder caused by mutations in the RAS/MAPK pathway. Multiple giant cell lesions are a rare sequelae of disruptions in this pathway, termed Noonan-like multiple giant cell lesions (NL/MGCLs). Medical management of these tumors rather than surgical intervention is preferential as the lesions are benign but locally destructive and recurring. This case series describes four male pediatric patients with Noonan syndrome and multiple giant cell lesions of the jaw treated with denosumab, a monoclonal antibody to receptor activator of nuclear factor kappa B ligand (RANKL), which has been approved for the treatment of malignant giant cell tumors in adults but not evaluated for safety or efficacy in children. All four pediatric patients responded clinically and radiographically to the treatment. Adverse events occurred in a predictable pattern and included hypocalcemia and joint pain during the initiation of treatment and symptomatic hypercalcemia after the cessation of treatment. Growth was not significantly impaired in these skeletally immature patients. This case series demonstrates how a weight-adjusted denosumab dose can effectively treat NL/MGCLs and provides laboratory data for consideration of the timing of monitoring for known side effects.