CRS is a heterogeneous disease process that can arise in odontogenic disease from the maxillary teeth. The histopathologic features of CRSo have yet to be determined and may have important implications on disease management and the need for escalation of therapy.

This study aims to characterize the histopathologic features of CRSo and determine whether the inflammatory profile of CRSo contributes to its recalcitrance to medical therapy and the need for surgery in a subset of patients with this disease.

Twenty-three CRSo, 38 CRSwNP, and 53 CRSsNP patients who underwent FESS were analyzed. Compared to CRSsNP, CRSo exhibited increased moderate-severe inflammation. Compared to CRSwNP, CRSo had decreased squamous metaplasia and reduced fibrosis. Eosinophilia was prevalent in CRSo but to a lesser extent than in CRSwNP. CRSo cases had significantly lower mean LMS compared to CRSwNP.

The study concluded that CRSo exhibits histopathologic features similar to those of CRSsNP with more severe inflammation. Moreover, eosinophilia, which is not typically considered to coexist with CRSo, was present in a large portion of CRSo patients. These findings may help explain at the inflammatory level why exceptional cases of CRSo may be recalcitrant to medical and dental therapy.