A 51-year-old female presented with pigmented bands across all fingernails and toenails. She has chronic myelogenous leukemia and is receiving imatinib for 6 months, along with rabeprazole, cefadroxyl, domperidone, fluconazole, and levocetirizine. Onychoscopy revealed multiple longitudinal grey lines within transverse grey bands of homogeneous chromonychia.
Negative results for HIV, deficiency of vitamin B12, hyperthyroidism, hyperbilirubinemia, Addison's disease, Cushing's syndrome, and scleroderma. Any suggestion for the cause and also the next course of action? Could this be drug-related?