Molecular defects in mastocytosis: KIT and beyond KIT.

In all variants of mastocytosis, activating KIT mutations are frequently found. In adults, neoplastic mast cells (MCs) cells show the KIT mutation D816V, whereas in children, MCs invading the skin are frequently positive for non-KIT D816V mutations. The clinical course and prognosis of the disease vary among patients with systemic mastocytosis (SM). Additional KIT-independent molecular defects might cause progression. Additional oncogenic lesions have recently been identified in advanced SM. In advanced SM the presence of additional genetic lesions or altered signaling worsening the prognosis might lead to the use of alternative therapies such as combined antisignaling targeted treatments or stem cell transplantation.