Aspergillus mastoiditis with intact tympanic membrane in immunocompetent host. Aspergillus mastoiditis is a very rare condition usually observed in immunocompromised patients. Masked mastoiditis is defined as a subclinical infectious inflammatory process of the mucosal lining and bony structures of the mastoid air cells with intact tympanic membranes. To our knowledge, our report of a masked Aspergillus mastoiditis occurring in a 71-year-old diabetic woman is only the second case of masked mastoiditis in the literature. Aggressive medical and surgical management are necessary to avoid a fatal outcome from this invasive infection.