Differential pathology of nasal polyps in cystic fibrosis and atopy.

Nineteen nasal polyps from 13 patients were examined histologically. Nine polyps from 
seven cystic fibrosis (CF) patients could be positively identified by a 
triad of observations: delicate, barely visible basement membrane of surface epithelium 
without submucosal hyalinization, lack of extensive infiltration of eosinophils (Giemsa stains), 
and a preponderance of acid mucin in glands and cysts of 
the polyp and in its surface mucous blanket (Alcian Blue-periodic acid- 
Schiff stains). Two polyps from two patients with CF and atopy 
showed the characteristic findings of CF without modification. Eight polyps from 
four atopic patients without CF were identified by the reverse triad 
of changes: extensive thickening of the epithelial basement membrane and its 
extension into the submucosa as an irregular hyaline membrane, high stromal 
eosinophil count, and mainly neutral mucin in mucous glands, cysts, and 
mucous blanket. Hyperplastic mucous glands, mucous cysts of variable sizes, focal 
metaplasia of surface epithelium, and acid mucin in goblet cells were 
considered nonspecific lesions. 