Foreign Bodies in Sinonasal Tissues: A Potential Pitfall yet a Hint to Oroantral Fistulas.

Foreign bodies in the maxillary sinus are infrequent findings with various organic and inorganic materials have been reported. Most are iatrogenic due to abnormal communications between the oral cavity and the sinus cavity, predominantly secondary to dental and oral procedures. Oroantral fistulas might be asymptomatic incidental findings or may present with sinusitis-related symptoms. Even though oroantral fistulas are frequently encountered iatrogenic complications, most studies focused on radiologic findings and surgical closure procedures. A few cases reported the histopathologic findings of foreign body-related antral sinusitis. Our aim is to report three cases of chronic maxillary sinusitis induced by various foreign bodies of oral and dental origin associated with oroantral fistulas. Our focus is to highlight the different histopathologic patterns, potential pitfalls and helpful clues of foreign body-induced maxillary sinusitis. Altered foreign bodies in procured sinus specimens might be missed, misinterpreted or ignored by pathologists. Obvious vegetable food remnants were detected, but subtle vegetable residuals showed pulse granuloma, rings and sheet-like patterns embedded in the granulation tissue and fibrous stroma. Some materials mimicked fungal hyphae while others were ignored as nonspecific debris. Periodic acid Schiff stain and polarizing light helped delineate their nature. Other helpful hints included the presence of oral-type squamous epithelium, crystals, hemosiderin pigments, dental materials such as alvogyl, and microorganisms of oral origin for example Actinomyces. Our series emphasizes the importance of correct recognition of foreign bodies of oral and dental origin in paranasal specimens to guide clinicians to the possibility of oroantral fistula-associated odontogenic sinusitis versus conventional rhinosinusitis.