Papillary carcinoma in amyloid goitre.

Amyloid goitre is a rare lesion characterized by a diffuse and bilateral enlargement of the thyroid gland due to amyloid deposition. It is uncommon that a massive and widespread amount of adipose tissue deposition is found within these lesions and only in exceptional cases a differentiated carcinoma can develop. We describe the third example of thyroid carcinoma, arising in a 74-year old female who had also massive adipose thyroidal metaplasia, within amyloid goitre. The Congo red stain confirmed the diagnosis of amyloid goitre. Immunohistochemistry showed reactivity with MoAb against amyloid fibril protein A. The patient suffered from renal failure of undetermined aetiology for three years, but neither systemic amyloidosis nor risk factors for its development were found. It is important to correctly diagnose amyloid goitre both to rule out the presence of a differentiated thyroidal carcinoma and to search for amyloid infiltration in other organs in view of an early appropriate therapy.