Inclusion Criteria:

1. Patients with one of the following documented mastocytosis:

- Smouldering systemic mastocytosis

- Indolent systemic mastocytosis with organomegaly

- Indolent Systemic Mastocytosis having 2 infiltrated organs (skin and
bone-marrow)

- Any mastocytosis with in the last 6 months at least 3 anaphylactic shocks or
syncops requiring either use of adrenaline or medical assistance

- Cutaneous Mastocytosis (CM)

2. Skin biopsy-documented mastocytosis and evaluable disease based upon:

- Histological criteria: typical infiltrates of mast cells in a multifocal or
diffuse pattern in skin biopsy

- Clinical criteria: typical skin lesions (maculopapular, urticaria pigmentosa,
mastocytoma)

3. Missing data (c-kit molecular analysis not done) or documented presence of an
activating point mutation in the phosphotransferase domain of c-kit such as D816V
c-kit mutation in at least one infiltrated organ (bone marrow or skin)

4. Refractory to at least one of the symptomatic treatments such as:

- Anti H1

- Anti H2

- Proton pump inhibitor

- Osteoclast inhibitor

- Cromoglycate Sodium

- Antileukotriene

- Other therapies used for the symptomatic care

5. Handicap defined as at least one of the following handicaps:

- pruritus score ≥ 6

- number of flushes per week ≥ 7

- number of stools per day ≥ 4 ,

- number of mictions per day ≥ 8 ,

- QLQ-C30 score ≥ 60,

- Hamilton score ≥ 10

Exclusion Criteria:

1. Patients with one of the following mastocytosis:

- Systemic Mastocytosis with an Associated clonal Hematologic Non Mast cell
lineage Disease (SM-AHNMD)

- Mast cell leukemia (MCL)

- Aggressive systemic mastocytosis (ASM)

2. Patient with a major surgery within 2 weeks prior to study entry

3. No vulnerable population will be included in this study

- Life expectancy < 6 months.

- Patient is < 5 years free of malignancy, except treated basal cell skin cancer
or cervical carcinoma in situ.

- Patient with grade III/IV cardiac problems as defined by the New York Heart
Association Criteria. (i.e., congestive heart failure, myocardial infarction
within 6 months of study)

- Patient has a severe and/or uncontrolled medical disease.

- Patient has a known diagnosis of human immunodeficiency virus (HIV) infection