Histopathological findings of chronically inflamed maxillary sinus mucous membrane were treated using grading codes for computer processing. The criteria prepared for this purpose were as follows: 1) thickness of mucous membrane, 2) infiltration of inflammatory cells, 3) infiltration of eosinophils, 4) edema, 5) polypoid change, 6) fibrosis, 7) vascularization, 8) numerical presence of proper mucosal glands, 9) increase in goblet cells, 10) formation of pseudoglands, 11) sloughing of epithelium, 12) stratification of epithelial cells, 13) thickening of basement membrane, 14) squamous metaplasia, and 15) dysplasia of epithelium.
In each criterion, the grade of pathological change was coded in the range of 1 to 4.
The mucous membranes studied in this investigation were taken from 923 maxillary sinuses of 582 patients. Correlation coefficients for all possible pairs of the 14 histopathological criteria were calculated and factor analysis was applied. From these results, a new system of classification was proposed in relation to the histopathological findings. It consisted of four main types, i.e., infectious type, edematous type, fibrous type, and mild type. Two subtypes of secretory type and non-secretory type were also suggested. Furthermore, allergic reaction was found by factor analysis as an independent factor.
The correlations of the histopathological type with the age of the patient, clinical findings, macroscopic findings obtained at the time of operation and in the postoperative course were also investigated.