Mastocytosis is very rare and highly heterogeneous group of disorders, characterized by the accumulation of clonal mast cells which can infiltrate several organs and tissues.

Bones are the most frequent localization of systemic mastocytosis. The aim of our research was to explain the potential role of sclerostin in the pathogenesis of bone disease in mastocytosis.

Mastocytosis is a heterogeneous group of disorders, characterized by the accumulation of clonal mast cells which can infiltrate several organs, such as the skin, bone marrow or liver. The skeleton is the most frequent localization of systemic mastocytosis (SM). Bone involvement occurs in approximately 70% of SM patients. Pathogenesis of mastocytosis bone disease is poorly understood.

The aim of our research is to explain the potential role of sclerostin, a recently discovered bone tissue protein, in the pathogenesis of bone changes in patients with mastocytosis.

The study group consists of adult patients with mastocytosis divided according to their clinical variants of disease (aggressive systemic mastocytosis - ASM, systemic mastocytosis with an associated hematological neoplasms SM-AHN, smouldering systemic mastocytosis - SSM, indolent systemic mastocytosis - ISM and cutaneous mastocytosis - CM; and group of healthy volunteers.

The concentration of sclerostin, bioactive sclerostin and expression of the SOST gene in human plasma and HMC-1.2 human mast cell culture supernatants is assessed. The Real-Time PCR method is used to evaluate the expression of sclerostin at the mRNA level, while the concentration of the sclerostin protein and its bioactive form is assessed using the enzyme immunoassay ELISA method. The obtained results are correlated with selected demographic, clinical, laboratory and radiological findings. Low-dose CT scan is used to assess bone changes.

These preliminary results could serve that sclerostin may be a new therapeutic target in patients with mastocytosis.

Inclusion Criteria:

• Age > 18 years
• Mastocytosis defined according to WHO criteria
• Known KIT mutation status

Exclusion Criteria:

• History of organ transplant
• Inability to give informed consent
• Pregnancy, Breastfeeding
• Vulnerable Patient, defined as: patient with another uncontrolled severe disease; patient under juridical protection

The study group consists of adult patients diagnosed with mastocytosis, divides according to the clinical variants: aggressive systemic mastocytosis (ASM), systemic mastocytosis with associated hematological neoplasm (SM-AHN), indolent systemic mastocytosis (ISM), smoldering systemic mastocytosis (SSM) and cutaneous mastocytosis (CM).

The diagnosis of mastocytosis should be established based on biopsy of the affected organ (bone marrow trephine biopsy, skin affected by the disease), following the 2022 WHO classification. The control group comprised 30 healthy volunteers matched with the study group in terms of age and gender.