Imatinib mesylate (Gleevec, also known as STI-571), is an approved oral treatment for patients with chronic myeloid leukemia (CML). It blocks the activity of Abelson cytoplasmic tyrosine kinase (ABL), c-Kit and the platelet-derived growth factor receptor (PDGFR). As an inhibitor of PDGFR, imatinib mesylate appears to have utility in the treatment of a variety of dermatological diseases. Imatinib has been reported to be an effective treatment for FIP1L1-PDGFRalpha+ mast cell disease, hypereosinophilic syndrome, and dermatofibrosarcoma protuberans. One report notes its effectiveness for treating HIV related Kaposi's sarcoma; imatinib has not been effective for the treatment of melanoma.