RESUMO
Granulocytic sarcoma is a rare malignant extramedullary neoplasm of myeloid precursor cells, occuring before or after onset of leukaemia. Involvment of the head and neck region is rare, generally concerning the orbit. To illustrate imaging findings of granulocytic sarcoma in an unusual location; maxillary sinus. We report a case of maxillary sinus granulocytic sarcoma in a 13-month old boy revealed by facial nerve palsy, ptosis and jugal swelling, without any evidence of haematological disorders. The patient underwent computed tomography and magnetic resonance imaging exam which demonstrated a non specific maxillary sinus mass with destruction of the orbit floor and the alveolar bone. Diagnosis was obtained after bone biopsy allowing histological and immunohistochemical studies. Granulocytic sarcoma is a serious condition because of the associated hematologic disorders. In a sinus or orbit location, imaging features are non specific. Unless hematologic history is present, diagnosis is difficult and an immuno histo chemical study is required