Ultrastructural Findings in a case of Benign Lymphoepithelial Lesion (Sjögren's Syndrome)

Abstract

A 71-year-old woman was admitted because of a slowly growing tumour in the left parotid region. Left-sided superficial parotidectomy was performed and light microscopic study of the surgical specimen disclosed a benign lymphoepithelial lesion. The clinical and laboratory examinations showed a sicca syndrome that is a variant of Sjögren's syndrome. Ultrastructural investigation of the resected material confirmed the light microscopic finding of a salivary gland architecture that was destroyed and replaced by lymphoid tissue, cell islands and seemingly proliferating ducts. The duct cells, as well as some of the cells constituting the islands, were characterized by a cytoplasm of low density, rather inconspicuous organelles and occasional delicate, irregular filaments. Other island cells exhibited more electron dense cytoplasm, tonofilaments and prominent desmosomes. In addition, there were cells in the islands that possessed features intermediate between those of the two other kinds of cells. No indeterminate myoepithelial cells were found. Although conclusive evidence is lacking, it is believed that the cell islands might be formed by proliferation and squamous cell metaplasia of duct cells.