Bone Abstracts (2016) 5 P474 | DOI: 10.1530/boneabs.5.P474

Defining a new severity classification and searching for a pronostic factor in cherubism: NFATc1 localization is the answer

Natacha Kadlub1,3, Quentin Siessecq3, Louise Galmiche4, Marie-Paule Vazquez3, Cécile Badoual4, Ariane Berdal1,2, Arnaud Picard1,3, Vianney Descroix1,2 & Amélie Coudert1,2

1INSERM U1138 – Oral Molecular Pathophysiology, Paris, France; 2UFR d’Odontology – Université Paris Diderot, Paris, France; 3APHP, Necker Enfants Malades, Service de Chirurgie Maxillo-faciale et Plastique, Paris, France; 4APHP, Hôpital Européen Georges Pompidou, Service d’Anatomopathologie et cytologie, Paris, France.

Cherubism is a rare genetic disease (OMIM #118400) characterized by a massive jaw bone osteolysis. This pathology appears around 2–5 years old and in the less severe cases spontaneously regresses after puberty. So far the only treatment available is surgery, often disabling and traumatic. As the cherubism pathophysiology is not yet understood, we carried out a thoroughly characterization of the cherubism granulomas from ten unrelated patients to determine the cells involved and find a potential severity marker. Cherubism presents variable phenotype, and as previously described, neither the SH3BP2 mutations nor the epidemiological data can explain the severity we observed in our patients group. However, our work allowed us to demonstrate that the granulomas are heterogeneous both between patients and for the same patient, preventing the definition of any biological marker. But, we were able to redefine the cherubism classification according to the cells and the NFATc1 cellular localization observed on the biopsies, allowing us to propose a better patient management preventing any unnecessary surgery. Ultimately, we confirm tacrolimus as an efficient drug treatment for the more severe cases.