Successful treatment of KIT D816V-positive, imatinib-resistant systemic mastocytosis with interferon-alpha.

We describe a case of systemic mastocytosis associated with myelodysplastic syndrome. The bone marrow showed multifocal clusters of mast cells and myeloid dysplasia. Sequencing of the KIT DNA revealed a point mutation at codon 816 including a substitution of valine for aspartic acid (D816V). The patient's tumor did not respond to imatinib; however, interferon-alpha reduced the bone marrow mast cells and serum total tryptase. The patient remains alive at one year after the diagnosis without disease progression.