Heterogeneity of cytokeratin expression as revealed using monoclonal antibodies in salivary adenocarcinomas

Numerous neoplastic lesions of the salivary glands often share a number of similar histopathological features and different areas of the same tumor specimen, not infrequently, may show a diverse histomorphology. The present study evaluates expression of single keratin proteins recognized by monoclonal anti-K7, K8, K18, K19 and keratins recognized by monoclonal KL1 and K8.12 in tubular-duct-like or cribriform structures, solid nests, clear cells, microcystic, basaloid cells and squamous metaplastic histomorphology present in tissue specimens of adenoid cystic carcinoma (n=11), acinic cell carcinoma (n=5), polymorphous low grade adenocarcinoma (n=1) and adenocarcinoma, not otherwise specified (NOS, n=5) of salivary glands. Expression of vimentin in the epithelial tumor cells was further evaluated using an anti-vimentin monoclonal antibody. A great heterogeneity of keratin expression was observed in the luminal and abluminal cells forming the tubular-duct-like and cribriform structures. The abluminal cells in more than half of the instances of adenoid cystic carcinoma had immunoreactive vimentin. In addition, heterogeneity was more pronounced in tumor cells forming the solid nests, comedo-necrosis, microcysts, clear cells or squamous metaplasia. A heterogeneity of keratin profile in different histomorphologies of different tumor types and even in different areas of the same tumor specimen, in the present study, and the available evidence so far limits the use of cytokeratin immunostaining in the differential diagnosis of neoplastic salivary lesions and characterization of a particular histomorphology which, in many instances, are ubiquitous in different tumor subtypes.