Distinct features of chronic rhinosinusitis with and without nasal polyps

Background: Based on the presence of nasal polyps on endoscopy, chronic rhinosinusitis (CRS) may be clinically divided in CRS with nasal polyps and CRS without nasal polyps. It is unclear, whether CRS with nasal polyps and CRS without nasal polyps represent different disease entities or just different stages of one single disease. In case of one disease, only minor histopathological differences between CRS with small early-stage polyps (CRSNP⁽⁺⁾) and CRS without nasal polyps (CRSNP^-) were expected. Methods: Patients with CRSNP⁽⁺⁾ confined to the infundibular region or CRSNP^- were selected. Histochemical and immunohistochemical characterization of ethmoidal mucosa was performed on formalin-fixed and paraffin-embedded tissue specimens. Frequency and distribution of eosinophils, neutrophils, mast cells, IgE⁺ cells, macrophages, B- and T-cell subsets, natural killer cells, plasma cells and goblet cells were assessed. In addition, the thickness of the basal membrane was evaluated. Results: Nine CRS patients without detectable polyps, and 11 patients with small early-stage polyps confined to the infundibular region were selected. Despite adjacent polyp stage, the amount of round cell infiltration (P < 0.05), number of eosinophils (P < 0.05), and plasma cells (P < 0.01) significantly differed in the ethmoidal specimens from patients of the two groups. Conclusion: Substantial histopathological differences were observed in ethmoidal mucosa of CRSNP⁽⁺⁾ and CRSNP^- patients. Thus, the results of this investigation support the concept that CRS with nasal polyps and CRS without nasal polyps are two different disease entities rather than different stages of one single disease, but may also be interpreted as a higher degree of inflammation.