Morphological and clinical characteristics of antrochoanal polyps: comparison with chronic inflammation-associated polyps of the maxillary sinus

Objectives: to compare morphological and clinical features of antrochoanal polyps and chronic inflammation-associated polyps of the maxillary sinus. Study design: histological and scanning electron microscopic examination of ten antrochoanal polyps and ten chronic inflammation-associated polyps of the maxillary sinus; comparison of clinical data in both groups of patients. Methods: following surgical removal, the polyps were halved, the halves being processed for routine light microscopy (formalin fixation, paraffin embedding, HE staining) and scanninng electron microscopy (formaldehyde/glutaraldehyde fixation, critical point drying, gold coating), respectively. Clinical data were retrospectively reviewed, tabulated and compared. Results: the antrochoanal polyps differed from chronic inflammation-associated polyps of the maxillary sinus only in a few minor features; slightly longer duration of the process, lower incidence of maxillary ostial obstruction, higher incidence of frequent headaches, persistent nasal obstruction, presence of cysts in the polyp stroma, thickened basement membrane, lower incidence of squamous cell metaplasia, and higher proportion of migratory cells in nasal smears. In two cases, allergy was diagnosed but it seemed not to influence the polyps, which did not show morphological features typical of allergy-associated (eosinophilic) polyps. Conclusions: In spite of minor differences, antrochoanal polyps can be regarded as chronic inflammation-associated polyps with cystic origin and peculiar localization.