Identification of serum proteins, thyroglobulin and antithyroid antibodies in the fluid of thyroid cysts.

Fluid from fourteen thyroid cysts has been submitted to electrophoretic and immunochemical procedures in order to describe the biochemical structure of the fluid. Two patterns have been identified: a pattern showing a composition similar to that of normal serum ("serum-like"); thyroglobulin concentration is low, IgG are sometimes above normal and hTg-Abs are frequently detectable. A second pattern shows instead, a picture in which serum protein fractions are largely denatured and not identifiable ("denatured"); thyroglobulin concentration has been found markedly increased. It is suggested that in "serum like" the formation of the cysts occurs in the interstitium, whereas in the "denatured" type cyst the hemorrhagic necrosis appears to be the consequence of a massive damage of the follicular tissue.