Inclusion Criteria:

1. Patients with documented Indolent systemic mastocytosis with handicap (ISMwh) having
at least 2 infiltrated* organs (skin and /or bone-marrow and/or internal organ).

2. Bone-marrow, or skin or internal biopsy-documented mastocytosis and evaluable
disease.

3. The absence of an activating point mutation in the phosphotransferase domain of c-Kit
such as D816V c-Kit mutation in at least one of the two infiltrated organs: bone
marrow and/or skin and/or other tissue.

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

- a number of flush per day ≥ 1 ,

- a pruritus score ≥ 9 ,

- a number of stools per day ≥ 4 ,

- a Pollakyuria (on a per day basis) ≥ 8 ,

- a QLQ-C30 score ≥ 83 ,

- a Hamilton rating scale for depression ≥ 12

Exclusion Criteria:

1. Performance status > 2 (ECOG).

2. Inadequate organ function, except if the abnormalities are due to involvement by mast
cells