A case of amyloid goiter associated with intrathyroid parathyroid and lymphoepithelial cyst.

Diffuse enlargement of the thyroid gland accompanied by an interstitial tissue deposition of amyloid is a special entity termed an amyloid goiter. An amyloid goiter is a rare thyroid lesion, which has been described a long time ago. In this report, we add a new classic case of amyloid goiter that differs from other reported cases in its association with intrathyroid parathyroid and lymphoepthelial cyst involved with amyloidosis. The presence of parathyroid tissue inside the thyroid parenchyma and surrounded by amyloid material elicited a diagnostic problem due to suspected medullary carcinoma. Careful histological examination and immunohistochemical staining for parathormone and calcitonin have largely helped in the differential diagnosis. Bilaterality, diffuse, and homogeneous involvement of the thyroid gland, with absence of definite masses, all direct the diagnosis toward amyloid goiter.