FINE STRUCTURE AND GENESIS OF ACINIC CELL CARCINOMA (AZINUSZELLTUMOR) OF GLANDULA PAROTIS

In four cases of acinic cell carcinoma of the parotid gland the fine structure of the tumor cells shows striking similarities to the serous acinar cells from human salivary glands. A detailed investigation of the cellular inclusions in the tumor cells reveals that two groups of cell inclusions occur: One group of tumor cell inclusions consists of electron dense amylase-resistant PAS-positive granules which correspond to the proenzyme granules of the serous acinar cell in the salivary glands. A second group of cell inclusions is electron transparent and PAS-negative. These inclusions are comparable in their morphological and fine structural properties to similar inclusions which can be found in the human serous salivary acinar cell, especially in the state of so-called mucoid degeneration. The electron-transparent cellular inclusions are interpreted to be the consequence of a disturbed production of secretory precursors occurring in damaged or less differentiated cells. Their presence in the cells of the acinic cell carcinoma explains some of the difficulties in the diagnosis of these rare tumors. © 1968 Springer-Verlag.