Histologic structure of antrochoanal polyps.

The antrochonanal polyp (ACP) is defined as a maxillary sinus polyp that originates in the maxillary sinus, passes through the sinus ostia, and extends into the choana. The aim of this study was to compare the histologic findings of 40 cases of ACP with those of allergic and non-allergic nasal polyps, and so possibly to elucidate the pathogenesis of ACP. No allergy could be verified in any of the ACP patients. Inflammatory cell infiltration was significantly more severe in the ACP group than in the allergic polyp group. Eosinophilic infiltration was significantly less severe in the ACP group than in the allergic polyp group. Edema was not significantly different between the ACP, allergic, and non-allergic groups. In the ACP group, the presence of submucous glands was significantly less pronounced than in the ordinary nasal polyp groups. The fibrous type was present significantly more often than the infiltrative or granulating type in the ACP group. The histologic findings and clinical features of the ACP indicate that it has little causal relationship with nasal allergy but is all the more intimately associated with inflammatory processes. The paucity of submucous glands suggests that the ACP results from edematous hypertrophy of the respiratory epithelium rather than from distension of the glandular structures.