Evidence of p53 immunohistochemical overexpression in ethmoidal mucosa of woodworkers.

A high risk of neoplastic transformation of nasal and paranasal sinuses mucosa is related to the occupational exposure to wood dust, however no conclusive data have been reported up to now about morphological precursors of these tumors, mechanisms of carcinogenesis and role of p53 gene. Immunohistochemical overexpression of protein p53 (DO7 clone) by epithelial cells of ethmoidal mucosa was investigated on 60 woodworkers occupationally exposed for a minimum of 10 years, on 50 functional and/or esthetic nasal surgery patients (control group) and on 15 cases of intestinal-type adenocarcinoma, 10 of these involving subjects who had a longtime exposure to wood dust. In almost all the woodworkers (92%) the normal ciliated epithelium showed tracts of squamous metaplasia. The mean percentage of p53-positive cells in woodworkers and in controls was 28.6 and 7.97%, respectively, in metaplastic epithelium (P<0.001), 11.7 and 2.08% in ciliated epithelium (P<0.001), 12.46 and 1.03% (P<0.001) in the sero-mucous glands of the nasal stroma. Both in tracts of metaplastic epithelium and in those of ciliated epithelium, positive cells were distributed in basal and suprabasal layers. A high number of p53-positive cells was also observed in the normal ciliated epithelium close to the neoplastic cells, of intestinal-type adenocarcinomas affecting subjects with longtime exposure to wood dust. Moreover, a higher number of p53 positive neoplastic cells was showed by the cases occurring in occupationally exposed patients than by the others. The following conclusions can be drawn: (1) in the ethmoidal mucosa, a region at high risk of carcinogenesis in subjects exposed to wood dust, epithelial cells overexpress p53 protein, and this may be linked to the presence of p53 gene mutations; malignant transformation, as at other head and neck sites, may thus occur through this pathway; (2) the presence of p53 overexpression in sero-mucous glands is in keeping with the histogenesis of some tumors from these structures; (3) since tumors of nose and paranasal sinuses, mainly adenocarcinoma, are recognized as occupational neoplasias, immunohistochemical evaluation of p53, perhaps combined with molecular methods, could be the first step to detect subjects at high risk of carcinogenesis among woodworkers.