Etiology of Nasal Polyps in Cystic Fibrosis: Not a Unimodal Disease

Objectives: The objective was to determine whether the polyp subtypes observed in cystic fibrosis (CF)-related sinusitis were similar to those observed in non-CF-related sinusitis. Methods: Polyp and mucus samples were collected from CF patients who presented for sinus surgery. The polyps underwent histologic and cytochemical evaluation for the presence of lymphocyte cell populations and their respective cytokine markers. The mucus samples were evaluated for DNA content. Results: Of the polyps, 42% had an eosinophilic infiltrate, of which 80% had an additional mixed neutrophilic infiltrate. Of the remaining polyp samples, 42% did not have a granulocytic infiltrate, consistent with non-eosinophilic polyps. All samples had CD138-positive plasma cells. The mucus samples from the patients with CF showed higher extracellular DNA concentrations than did the mucus samples from patients with non-CF sinus disease. Conclusions: Cystic fibrosis-related polyps demonstrated an eosinophil-based dichotomy similar to that of idiopathic non-CF-related polyps. Many also demonstrated neutrophilic infiltrate, indicating that chronic mucus stasis and infection complicate the disease. Agents capable of reducing extracellular DNA may help manage sinusitis in CF patients.