PAPILLARY CYSTADENOCARCINOMA OF SALIVARY-GLANDS - AN IMMUNOHISTOCHEMICAL STUDY

The immunohistochemical features of 16 cases of papillary cystadenocar cinoma of salivary glands using a panel of monoclonal and polyclonal a ntibodies were evaluated. The specimens were from patients postoperati vely diagnosed as papillary cystadenocarcinoma of salivary glands wher e the age of the patients ranged from 20-70 years, males were more com monly affected than the females and parotid gland was the most commonl y affected site. The cytokeratins detected by MoAb KL1 and K8.12 were positive in all cases showing a heterogeneity in intensity of reaction . A coexpression of vimentin with cytokeratin was found in 10 cases. T he tumor cells had a coexpression of S-100 protein and neuron specific enolase (NSE). Glial fibrillary acidic protein (GFAP) was positive in one case with multiple expression of cytokeratins, vimentin NSE, S-10 0 protein. The polymorphic mucin MAM-6 was positive in all cases and M AM-3 in 8 cases showing different intensity of reaction. The tumor cel ls were positive for lysozyme (8 cases), lactoferrin (10 cases) and al pha-1-antichymotrypsin (10 cases). The immunoreactive c-erbB-2 oncopro tein on the cell surface membrane was detected in 2 cases. The labelin g index of proliferating cell nuclear antigen in the tumor cells range d from 3.8 to 43.2% (mean 14.2 +/- standard deviation 9.8). Histopatho logical feature and a heterogeneity of multiple expression of tissue m arkers may suggest that a population of cells in papillary cystadenoca rcinoma may be counterparts of modified myoepithelial cells of pleomor phic adenoma that express epithelial, mesenchymal and neuronal differe ntiation although the role of myoepithelial cells in the genesis of th is tumor is not clear. However, disorganized stratification and malign ant transformation of ductal cells may be the most likely possibility in the histogenesis of this tumor.