COINVOLGIMENTO OSSEO NELLA MASTOCITOSI SISTEMICA

The Mast cells are cells that are found predominantly in the perivascular spaces of almost all tissues and that are easily recognizable for the cytoplasmic contents into metachromatic granules when they are stained by Giemsa or with Toluidine Blue. These granules contain numerous vasoactive and pro-inflammatory mediators that are released after mast cell activation by binding with the receptor for IgE by allergens or other factors. Mast cells derived from multipotent haematopoietic precursors bone marrow, which through the peripheral blood, migrate into the tissues where they differentiate into mature mast cells, under the influence of IL-3 and in particular of the Stem cell factor, which represents the KIT ligand (CD117) , a tyrosine kinase receptor constitutively expressed on mast cells and their precursors. The Mastocytosis is a clonal disorder characterized by an accumulation of mast cells in various organs (skin, bone, gastrointestinal tract, lymph nodes and spleen) and is related in most cases to a point mutation of the gene that encodes the receptor KIT. It differs fundamentally a form of cutaneous mastocytosis (MC), the most frequent and typical of childhood, and systemic mastocytosis (SM), involving at least one organ other than skin. There are no epidemiological data on the prevalence of mastocytosis in the general population: in a study reported 0.66 new cases of maculopapular cutaneous mastocytosis (urticaria pigmentosa-OP) / anno/100.000 inhabitants, while there are no data on the incidence of MS, and for the diagnostic difficulty is probably underdiagnosed disease. The mastocytosis can affect any age and male / female ratio reported varies from 0.8 to 1.5%. This is mostly a sporadic but rare forms are also described family.