title: Somatic c-KIT activating mutation in urticaria pigmentosa and aggressive mastocytosis: establishment of clonality in a human mast cell neoplasm.
abstract: Mastocytosis is characterized by accumulations of mast cells in various organs (1). Most cases are indolent and confined to the skin, where discrete mast cell infiltrates are associated increased epidermal melanin, a clinical picture known as urticaria pigmentosa (UP). Other forms of mastocytosis combine UP with aggressive involvement of other organs or with haemotologic abnormalities (1-4). It is not known whether all forms of mastocytosis are true neoplasms or whether some might represent reactive hyperplasias (5-7). The c-KIT proto-oncogene encodes a type III receptor tyrosine kinase (KIT) that is critical to the development and survival of mast cells and melanocytes (8-11). The ligand for KIT (KL) can stimulate mast cell development, proliferation, and mediator release (9,12-17), as well as melanocyte proliferation and pigment production (18-20). To determine the role of c-KIT in the pathogenesis of mastocytosis, we examined tissue and cells isolated from a patient with UP and aggressive systemic mastocytosis with massive splenic involvement. We found a mutation that results in constitutive activation and expression of c-KIT in mast cells of both skin and spleen. This is the first in situ demonstration of an activation c-KIT mutation in neoplastic cells. It also demonstrates the clonal and neoplastic nature of this form of mastocytes.
authors.affiliation: Department of Dermatology, Yale University School of Medicine, New Haven Connecticut 06510, USA.
authors.forename: B J
authors.initials: BJ
authors.lastname: Longley
authors.forename: L
authors.initials: L
authors.lastname: Tyrrell
authors.forename: S Z
authors.initials: SZ
authors.lastname: Lu
authors.forename: Y S
authors.initials: YS
authors.lastname: Ma
authors.forename: K
authors.initials: K
authors.lastname: Langley
authors.forename: T G
authors.initials: TG
authors.lastname: Ding
authors.forename: T
authors.initials: T
authors.lastname: Duffy
authors.forename: P
authors.initials: P
authors.lastname: Jacobs
authors.forename: L H
authors.initials: LH
authors.lastname: Tang
authors.forename: I
authors.initials: I
authors.lastname: Modlin
mesh_terms: D000328:Adult; D001483:Base Sequence; D002999:Clone Cells; D017931:DNA Primers; D006801:Humans; D007124:Immunoenzyme Techniques; D008297:Male; D008407:Mast Cells; D008415:Mastocytosis / Q000235:genetics* / Q000503:physiopathology; D008969:Molecular Sequence Data; D009154:Mutation; D009372:Neoplasms, Connective Tissue / Q000235:genetics*; D000090063:Proto-Oncogene Mas; D019009:Proto-Oncogene Proteins c-kit / Q000235:genetics*; D013158:Splenic Diseases / Q000235:genetics; D014582:Urticaria Pigmentosa / Q000235:genetics*
chemical_list: D017931:DNA Primers; C000715470:MAS1 protein, human; D000090063:Proto-Oncogene Mas; D019009:Proto-Oncogene Proteins c-kit