SUMMARYHere we report a case of invasive pansinusitis with proptosis of the right eye caused by Aspergillus flavus in an immunocompromised patient with acute biphenotypic leukemia without aggressive therapy response. KEYWORDS: Leukemia; Aspergillus flavus; Invasive sinusitis.A 17-year-old white man was diagnosed with acute biphenotypic leukemia and underwent chemotherapy with cytarabine, idarubicin and etoposide (7+3+5) followed by high dose cytarabine. After an initial complete remission of short duration he relapsed and underwent a second course of induction chemotherapy with metoxantrone and etoposide without response. The patient was pancitopenic and with persistence of blasts; biphenotypic acute leukemia (lineages myeloid and T-lymphoid) demonstrated in a bone marrow biopsy.He was being treated for febrile neutropenia when developed a fever of 39 °C and headache. Physical examination showed edema, hyperemia and proptosis in the right eye with periorbital swelling laterally. Computed tomography (CT) scan of the head revealed opacification of the right maxillary, ethmoidal, sphenoidal and frontal sinuses. Bone erosion was also observed in the medial wall of the right maxillary sinus (Fig. 1). Lung CT scan revealed no abnormalities.