Oral lichenoid reaction to imatinib (STI 571, Gleevec).

Imatinib or STI 571 is a phenylaminopyrimidine derivative and a member of a new class of drugs known as signal transduction inhibitors. These compounds specifically inhibit the proliferation of v-abl- and bcr-abl-expressing cells and have recently been approved as treatment for chronic myeloid leukaemia (CML). Results have been promising, and imatinib may well be the best single agent for the treatment of CML in the near future. Here we report an erosive oral lichenoid eruption confined to the buccal mucosa and dorsum of the tongue which appeared 12 weeks after commencement of imatinib in a 72-year-old woman with CML. The histology was consistent with a lichenoid drug eruption. The lesions resolved upon withdrawal of the drug. To our knowledge, this is the first reported lichenoid reaction to imatinib, and in the setting of CML it must be differentiated from idiopathic lichen planus, paraneoplastic pemphigus and graft-versus-host disease.