Mast cell disorders constitute a heterogeneous group of diseases, including :

• mastocytosis, i.e. cutaneous, indolent and severe forms of the disease, such as aggressive mastocytosis and mast cell leukemia) ;
• mast cell-associated diseases such as mast cell activation syndrome (idiopathic, secondary or clonal), affecting both children and adults.

No epidemiological data are currently available in France.

In France, medical care of mast cell disorders is mainly provided by a rare disease network (CEREMAST), whose CRMR is located at the Necker Enfants Malades hospital in Paris. A total of 20 centers are located throughout France.

Our aim is to use this network to study patients suffering from these diseases. The overall aim of the study is to improve the understanding, diagnosis, prognosis, recognition and management of patients with mastocytosis.

Inclusion Criteria:

1. Children from birth and adults of any age

2. With one of the following mast cell diseases:

   • Mastocytoses (cutaneous, systemic and sarcomas) Defined according to the WHO 2016 classification
   • Mast cell activation syndromes (idiopathic, secondary and clonal)
   • Other mast cell activation disorders (MCAD-NOS), Defined according to the Vienna classification
   • Pre-mastocytosis or MMC (1 to 2 criteria according to WHO 2016 classification).

3. Managed in France in a rare disease reference, constitutive or competence center (CEREMAST) with DGOS labelization.

Exclusion Criteria:

1. Opposition of the patient or his/her parents to participation in the study.

Patient with mast cell diseases, managed in France in a rare disease reference center CEREMAST.

13000 pateints estimated.