Significance and function of multinucleate giant cells in de Quervain's thyroiditis.

Thyroid gland resections from 12 patients suffering from de Quervain's thyroiditis were investigated by light-, electron- and immunofluorescence-microscopy as well as enzymehistochemically . Several granulomas were serially sectioned. The giant cells of de Quervain's thyroiditis arise from the fusion of mononuclear precursors. They usually have ordered nuclei similar to the Langhans type. Histochemically they show the reactions of macrophages. Most enzyme activity is demonstrable in the 'working poles' of the giant cells abutting the residual thyroid colloid. We assume that as a result of polarization and orientation they are able to degrade the colloid in a direct manner. Sometimes they fuse to form syncytia which totally enclose the colloid.