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.

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

A case of amyloid goiter in a 73-year-old man with systemic amyloidosis complicating long lasting rheumatoid arthritis is reported. The thyroid gland was massively infiltrated with amyloid and contained foci of fat tissue and epithelial solid cell nests. Incidentally, a cyst lined by squamous epithelium, with small amount of lymphocytes in the subepithelial stroma was found. This cyst fulfilled the criteria for the diagnosis of a lymphoepithelial cyst presumably of branchiogenic origin. The herein described case of simultaneous occurrence of branchiogenic cyst and amyloid goiter represents, to our best knowledge, a unique coexistence of these two entities. The possible relationship between these lesions and their differential diagnosis is discussed.

Ryska A

Papers

Lymphoepithelial cyst of the thyroid coexistent with amyloid goiter