Pituitary adenoma calcification.

Calcifications have been found in 9 of 137 different pituitary adenomas (6.6%) that have been examined with skull roentgenograms, light microscopy, and electron microscopy. Electron microscopy was most efficient because seven cases showed positive findings. Skull x-ray films showed calcification in four and light microscopy in only two cases. Six adenomas showed signs of increased prolactin production (either by direct determination or presence of galactorrhea). Two pateitns with calcifications on skull x-ray films and negative microscopic examinations did not show signs of any hormone secretion. The ultrastructural examination showed that the process of calcification started in single necrotic cells undergoing fibrillary transformation. No large areas of necrosis were present as seen in other forms of dystrophic calcification. The deposits consisted of dense accumulation of radially oriented hydroxyapatite crystals. The observations suggest that local factors and the type of hormone secreted may play an important role in the calcification pattern of pituitary adenomas.