Study of Cellular Heterogeneity in Patients With Mastocytosis

Inclusion Criteria:

* Criteria related to the study population:
* Subject affiliated with a social security or insurance scheme
* Subject who has given written consent to his participation in the study
* Criteria related to the studied pathology:
* Subject diagnosed with isolated cutaneous or indolent systemic mastocytosis with associated skin involvement defined according to World Health Organization criteria (and/or international criteria for cutaneous mastocytosis)
* Subjects whose KIT mutation status is known in the skin, bone marrow, and blood

Exclusion Criteria:

* Criteria related to the study population:
* Sun exposure of the biopsied areas expected within the 4 weeks preceding
* Subjects who have had exposure to sunlight or artificial UV radiation within the 2 weeks preceding inclusion at the biopsied areas
* Adult patients under legal protection, guardianship, or curatorship
* Pregnant or lactating women
* Criteria related to the studied pathology:
* Subjects with an advanced version of the pathology or advanced systemic mastocytosis (SAMA)
* Subjects with a known history of allergy or intolerance to local anesthetics
* Subjects who have previously shown abnormalities in skin healing or any other contraindication to skin biopsy
* Subjects with recognized addiction to alcoholism or drug abuse
* Subjects with a hereditary or acquired disorder of hemostasis
* Subjects with a severe or acute chronic condition judged by the investigator as incompatible with the trial
* Subjects presenting a clinically incompatible immune deficiency with the study
* Patients without a well-established diagnosis of mastocytosis
* Patients included in a therapeutic study for indolent systemic mastocytosis
* Treatment-related criteria:
* Any topical or systemic treatment for atopic dermatitis (including phototherapy) ongoing or stopped at least 14 days before the inclusion visit
* Systemic corticosteroids within the 4 weeks preceding the inclusion visit
* Ongoing systemic treatment likely to interfere with the healing process
* Subjects who have undergone physical treatment (radiotherapy, etc.) on the biopsy area in the past 6 months
* History of treatment or concomitant treatment that may interfere with the conduct of the study as determined by the investigator