Ouclar calcifications in primary hyperparathyroidism. Histochemical and ultrastructural study of a case. Comparison with ocular calcifications in idiopathic hypercalcaemia of infancy and in renal failure

Abstract

In a case of primary hyperparathyroidism, ocular changes were observed as vacuoles in the basal cells of the corneal epithelium, and by staining procedures, calcium was found in the corneal and conjunctival epithelia, the corneal endothelium and in the sclera. By electron microscopy, needle-like crystals of calcium hydroxyapatite precursors were found intracellularly, also in keratocytes. The crystals in the epithelial cells were often confined to the nucleus. In a case of idiopathic hypercalcaemia of infancy, similar crystals were found intracellularly in the corneal epithelial and stromal cells, and in this case extracellular deposits, morphologically identical with extracellular deposits in conjunctival biopsies from patients with renal failure, were also seen. These extracellular aggregations were probably also composed of hydroxyapatite. The difference in morphology between intracellular and extracellular deposits is discussed in the light of the serum values of the mineral ions found in the three groups of cases.