Multifocal papillary thyroid carcinoma associated with primary amyloid goiter.

Amyloid goiter is a rare condition characterized by a diffuse enlargement of the thyroid gland due to amyloid deposition. Extremely uncommon is the development of differentiated carcinomas within this type of lesion. We describe to our knowledge the sixth case of a papillary thyroid carcinoma within an amyloid goiter, arising in a 45-year old woman with chronic renal failure due to primary amyloidosis. This is the first case of a multifocal papillary carcinoma within an amyloid goiter which produces compressive symptoms. The patient suffered a total thyroidectomy with the histological diagnosis of amyloid goiter with a multifocal papillary carcinoma of follicular variant. The Congo red stain confirmed the diagnosis of amyloid goiter. Two years and a half after the surgery the patient is free of recurrence. Amyloid goiter can hide a differentiated carcinoma. To diagnose and early treat this pathology, the knowledge of the possible association between an amyloid goiter and a differentiated carcinoma is needed.