Alpha heavy-chain disease presenting as goiter.

A patient with alpha heavy-chain disease (alpha HCD) originally had presented with a goiter from an extramedullary plasmacytoma. Alpha HCD was diagnosed by both standard laboratory procedures and high-resolution two-dimensional gel electrophoresis. The fragment of the alpha chain had a molecular weight of 38,000 and consisted of seven major charge forms, with an isoelectric point range of 5.2-5.6. Since alpha HCD usually involves the gastrointestinal tract, the thyroidal involvement in this case is unusual.