The Granulocytic Sarcoma is a composed solid tumor of precursors of the granulocytes that usually occurs in carriers of Acute Myelogenous Leukemia (LMA), at the beginning of the disease or after remission. The localization in the secular bone is rare and can mimicking other frequent affections in this localization. CASE REPORT: Patient of 19 years with diagnosis of LMA in remission, presented complaint of intense otalgia, aural fullness and peripheral face paralysis the right. To the otoscopy it had bulging of the posterior wall of the external auditory conduit (CAE) and othorrea. The diagnostic hypothesis of OEN was made. In the complementary inquiry, it had rise of Protein C Reactive (PCR) e, in the topographic study, veiling of cells of mastoid and the right average ear, beyond lise osseous in the posterior wall of the CAE. The culture of the CAE was negative e, in the scintigraphy with marked leukocytes and phytate suppression, had been excluded inflammatory and infectious processes of the secular bone. Then it was submitted to the histopathological examination of material harvested for mastoidectomy, being compatible with undifferentiated neoplasias, whose immunohistochemistry concluded to be about granulocytic sarcoma (chloroma), for fallen again to extramedullary of the LMA. It did not have signals of return of the disease in the osseous marrow. Chemotherapy protocol was restarted, with improvement of pain and the otoscopy. The patient follows in accompaniment, with programming for heterologous transplant of osseous marrow. CONCLUSION: The affections of the secular bone present nonspecific symptomatology, generating diagnostic confusion. It must be intent for the possible distinguishing diagnostic, in order to allow precocious and adequate intervention.