Polymorphous Low Grade Adenocarcinoma of Minor Salivary Gland Origin in the Oral Floor ; Report of a case with an immunohistochemical study and an analysis of proliferative activity

Abstract

A case of polymorphous low grade adenocarcinoma (PLGAC)of minor salivary gland in the oral floor, an extremely rare location for PLGAC, is reported. The histopathology of in this case was characterized by cytological uniformity in a variety of morphological growth patterns, including tubular, solid, trabecular, papillary-cystic, and single file areas. Immunohistochemically, most of the tumor cells were positive for keratin, vimentin, and S-100 protein. Some tumor cells were positive and variably immunoreactive for muscle actin, epithelial membrane antigen(EMA), and carcinoembryonic antigen (CEA). The number of argyrophilic nucleolar organizer regions(AgNOR) is considered to be a reflection of the tumor proliferation rate. The numbers of AgNOR per nucleus in the tubular, solid, and papillary-cystic morphological growth patterns were 1.80 ± 0.08, 1.87 ± 0.04, and 1.78 ± 0.03, respectively. There was no correlation between the number of AgNOR and the growth pattern.