Invasive sinonasal actinomycosis: case report and literature review.

Actinomycosis is a rare anaerobic bacterial infection typically caused by Actinomyces israelii. Although part of normal flora in the oral cavity, and respiratory and digestive tracts, A israelii can give rise to pathologic infections most commonly reported in the oral cavity from odontogenic causes. We present a rare case of invasive actinomycosis presenting with extensive midface destruction involving the maxilla and paranasal sinuses, with mucosal necrosis mimicking an aggressive neoplasm. The diagnosis is usually reached only after histopathologic analysis showing characteristic sulfur granules with filamentous gram-positive, non-acid-fast bacteria. We review the literature on its epidemiology, clinical presentation, diagnosis, treatment, and prognosis.