Amyloid goiter: first manifestation of systemic amyloidosis.

Amyloidosis is an abnormal extracellular deposit, which can occur in several tissues. The mechanism is not clearly defined. In systemic amyloidosis, all the organs can be infiltrated, but amyloid goiter as the initial manifestation of systemic amyloidosis is an exceedingly rare condition. We report a rare case of a patient who presented an amyloid goiter as the first manifestation of systemic amyloidosis. This patient had a known Crohn's disease. He developed a goiter without compressive complications. Histologic examination revealed a diffuse amyloid deposition surrounding thyroid follicles. The gland was enlarged with an eosinophilic and amorphic deposit. Confirmation of amyloid was made by the presence of congophilia and apple-green birefringence under polarized-light microscopy. An immunoreactivity was seen with AA protein. Amyloid goiter is a rare manifestation of amyloidosis. About 250 cases of amyloid goiter have been reported in the literature. The goiter enlarges rapidly and progressively, often becoming compressive like thyroid cancer. The prognosis depends on the treatment of the amyloidosis and the underlying chronic disease.