Immunocytochemistry of acinic cell carcinomas and mixed tumors of salivary glands.

Antisera of several secretory products of the salivary gland were used to investigate the histogenesis of acinic cell tumors and mixed salivary gland tumors for comparison. Amylase, lactoferrin, secretory piece, and proline-rich protein (PRP) immunoreactivity was detected in the majority of acinic cell tumors; staining was focal, except for PRP, which was diffuse. Lysozyme immunoreactivity was rare. There was discordance for immunoreactivity with several antisera in identifiable tumor lobules of half of the neoplasms. An antikeratin serum outlined microcystic and follicular areas but rarely solid foci. These findings support the contention that acinic cell tumors derive from a tubular type stem cell. Lactoferrin and secretory piece immunoreactivity was not common in mixed tumors and was confined to scattered ductal cells and luminal contents. Rare small foci of amylase and PRP immunoreactivity were found in two mixed tumors only.