Imatinib Mesylate, is a tyrosine kinase inhibitor that has significantly altered the therapeutic landscape of chronic myeloid leukemia (CML), enabling most patients to experience extended survival and a better quality of life. Despite its clinical benefits, the drug is known to produce certain adverse effects, including pigmentation changes in the oral mucosa. Here we are presenting a rare case of a 57-year-old male who had chronic myeloid leukemia and has been under the chemotherapeutic agent Imatinib, since 2008 and in 2024 he discovered a large pigmented palatal mucosa lesion during a routine dental visit.