HISTOCHEMICAL AND BIOCHEMICAL DETERMINATION OF CALCIUM IN PLEOMORPHICADENOMA

Although calcification seldom occurs in pleomorphic adenoma, it often occurs in salivary glands, and so we decided to investigate the possib le role of calcium in this difference. A histochemical method using gl yoxal bis(2-hydroxyanil) demonstrated a small amount of calcium outlin ing lumina and separated cells of epithelial structures and associated with cells of myxoid and chondroid regions in pleomorphic adenoma, an d a conspicuous amount in the acini of the associated salivary glands. A biochemical method using dry ashing demonstrated a significantly hi gher level of calcium in the glands than in pleomorphic adenoma. The r esults indicate that the calcium is mainly associated with secretory g ranules, which are scarce in pleomorphic adenoma, and with proteoglyca n present intercellularly and in stromal regions of pleomorphic adenom a. The calcium in secretory granules is of possible importance in calc ification in lumina and epithelium, and that bound to proteoglycan is possibly released following necrosis to be of importance in stromal ca lcification. However, the overall low level of calcium in pleomorphic adenoma is the likely explanation for the usual lack of calcification.