Mots clés : leucémie aiguë myéloïde / hyperplasie gingivale / hémogramme / myélogrammeRésumé -Les auteurs se proposent, à partir de deux observations cliniques, de montrer qu'une LAM (leucémie aiguë myéloïde) peut, d'un côté, se présenter de manière classique avec confirmation biologique d'emblée et, de l'autre, se traduire par des manifestations cliniques, masquées par un contexte particulier où il est difficile de suspecter une LAM en première intention. L'intérêt de cette communication est de montrer qu'à partir de signes cliniques très différents tant dans l'exubérance que dans la discrétion, le diagnostic reste le même alors que l'issue est totalement opposée. Il ressort de cette expérience que toute expression buccale d'une pathologie générale doit être systémati-quement bilantée dès sa prise en charge initiale.Key words: acute myeloid leukaemia / gingival hyperplasia / complete blood count / bone marrow biopsy Abstract -Acute myeloid leukaemia: when clinical presentation represents a trap. The authors try to present through two clinical observations that a AML (acute myeloid leukaemia) can, in one hand, be recognized rapidly and induce a biological confirmation and, in the other hand, that the clinical manifestations could be concealed by a particular general context where the AML couldn't be diagnosed in the first intention. The first case describes a 39 year-old woman addressed to University hospital dental medicine clinic from Dijon by her physician for generalized gingival hyperplasia. The history shows a normal blood numeration two months before. The results of the complete blood count and bone marrow biopsy reveal a AML associated with intravascular coagulation. The second case presents a 39 year-old woman with a good health. The history shows a few recent specialized consultations: three times in gynaecology, two times in generalized medicine, once by the dentist and at the dental medicine clinic from Dijon. All these consultations didn't show any particularity except a gingivitis caused by her pregnancy. The patient went to the emergency for extreme oral pain, which were treated by morphine injection. She was then reoriented to the dental medical faculty. The patient is immediately hospitalised for complete blood analyses. The brutal aggravation of the general being of the patient associated with signs of neurological pain, leads us to realize in emergency a brain-tomograph. The result was a cerebral hemorrhagic which was followed in only a few hours by the death of the patient. The results of the biological examination show the existence of an AML. The aim of this paper is to present two cases with different clinical symptoms where the diagnosis is the same but the prognostic is strictly opposed. In conclusion, all patients with oral manifestation of their general disease must receive systematically a precise biological examination.La leucémie est définie comme étant une prolifération monoclonale maligne de cellules hématopoïétiques de la lignée blanche. Cette prolifération atteint soit la lignée...