Is there any association between Nasal Polyposis and Osteoma? A retrospective analysis of incidence of Paranasal Sinus Osteoma among 600 patients treated for Nasal Polyposis

Osteoma is a rare benign lesion of the skull, with an incidence of 0.6% of all benign tumours of paranasal sinuses. It is commonly asymptomatic, and mostly diagnosed incidentally at the imaging. The most frequent disturbs are: headache, nasal discharge and symptoms of inflammation. Osteoma is often associated with nasal polyposis and mucocele, which are usually considered as secondary lesions. Contrariwise, in our cases, we are prone to consider the osteoma as secondary to the inflammation associated with polyposis and mucocele. The physiopathology of these diseases was therefore reviewed to explain a possible relationship. We conducted a retrospective analysis in our ENT division from January 2010 to December 2016. In our cohort of 600 patients with nasal polyposis we found 20 cases of osteoid osteoma with an incidence of 3,33%. The mean age was 45,7 (+/-16,7 y.o.), with a Male/Female ratio of 2,3:1. In twelve cases the osteoma was located in the frontal sinus (70%), seven were implanted on the lateral part of the ethmoid roof (35%), and one extended from the ethmoidal to the frontal sinus (5%). The average tumour size was 11.04 ± 8,16 mm (range 2,88 mm– 19,2 mm). All patients underwent CT scan, clinical evaluation and ESS with histological examination. The collected data may suggest that chronic mucosal inflammation can induces bone modification and eventually lead to osteomas. We can hypothesize that paranasal sinus osteomas could represent a complication of nasal polyposis. Further investigations are needed to confirm this hypothesis.