Gamma heavy chain disease seen initially as gastric neoplasm

A patient with abdominal pain, weight loss, and a gastric mass was found to have a pleomorphic infiltrate of lymphocytes and plasma cells. Analysis of serum proteins revealed gamma heavy chains, which were detected in the urine as well. This case is unusual because of the extralymphatic involvement and the possibly unique character of the heavy chain, an insertion in added polypeptides.